Constrained random points on a circle: Difference between revisions
(→{{header|C sharp|C#}}: r.Next(403) should be r.Next(404) as the parameter is an exclusive upper-bound.) |
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for (int count = 0; count < 100; count++) |
for (int count = 0; count < 100; count++) |
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{ |
{ |
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var p = points[r.Next( |
var p = points[r.Next(404)]; |
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g.FillEllipse(brush, new Rectangle(290 + 19 * p.X, 290 + 19 * p.Y, 10, 10)); |
g.FillEllipse(brush, new Rectangle(290 + 19 * p.X, 290 + 19 * p.Y, 10, 10)); |
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} |
} |
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Revision as of 22:59, 21 April 2020
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
- .
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
11l
<lang 11l>F print_circle(lo, hi, ndots)
V canvas = [[0B] * (2*hi+1)] * (2*hi+1)
V i = 0
L i < ndots
V x = random:(-hi..hi)
V y = random:(-hi..hi)
I x^2 + y^2 C lo^2 .. hi^2
canvas[x + hi][y + hi] = 1B
i++
L(i) 0 .. 2*hi
print(canvas[i].map(j -> I j {‘♦ ’} E ‘ ’).join(‘’))
print_circle(10, 15, 100)</lang>
Ada
<lang Ada>with Ada.Text_IO; with Ada.Numerics.Discrete_Random; procedure Circle is
-- extreme coordinate values are -15:0, 15:0, 0:-15, 0:15
subtype Coordinate is Integer range -15 .. 15;
type Point is record
X, Y : Coordinate;
end record;
type Point_List is array (Positive range <>) of Point;
function Acceptable (Position : Point) return Boolean is
Squared_Sum : Natural := Position.X ** 2 + Position.Y ** 2;
begin
return 10 ** 2 <= Squared_Sum and Squared_Sum <= 15 ** 2;
end Acceptable;
-- first algorithm
function Generate_Random_Points
(Count : Positive := 100)
return Point_List
is
package RNG is new Ada.Numerics.Discrete_Random (Coordinate);
Generator : RNG.Generator;
Next_Point : Point;
Result : Point_List (1 .. Count);
begin
RNG.Reset (Generator);
for N in Result'Range loop
loop
Next_Point.X := RNG.Random (Generator);
Next_Point.Y := RNG.Random (Generator);
exit when Acceptable (Next_Point);
end loop;
Result (N) := Next_Point;
end loop;
return Result;
end Generate_Random_Points;
-- second algorithm
function Choose_Precalculated
(Count : Positive := 100)
return Point_List
is
subtype Possible_Points is Positive range 1 .. 404;
package RNG is new Ada.Numerics.Discrete_Random (Possible_Points);
Generator : RNG.Generator;
Point_Pool : Point_List (Possible_Points);
Next_Point : Point;
Next_Index : Possible_Points := 1;
Result : Point_List (1 .. Count);
begin
-- precalculate
Precalculate : for X in Coordinate'Range loop
Next_Point.X := X;
for Y in Coordinate'Range loop
Next_Point.Y := Y;
if Acceptable (Next_Point) then
Point_Pool (Next_Index) := Next_Point;
exit Precalculate when Next_Index = Possible_Points'Last;
Next_Index := Next_Index + 1;
end if;
end loop;
end loop Precalculate;
-- choose
RNG.Reset (Generator);
for N in Result'Range loop
Result (N) := Point_Pool (RNG.Random (Generator));
end loop;
return Result;
end Choose_Precalculated;
procedure Print_Points (Points : Point_List) is
Output_String : array (Coordinate, Coordinate) of Character :=
(others => (others => ' '));
begin
for N in Points'Range loop
Output_String (Points (N).X, Points (N).Y) := '*';
end loop;
for Line in Output_String'Range (2) loop
for Column in Output_String'Range (1) loop
Ada.Text_IO.Put (Output_String (Column, Line));
end loop;
Ada.Text_IO.New_Line;
end loop;
end Print_Points;
My_Circle_Randomly : Point_List := Generate_Random_Points; My_Circle_Precalculated : Point_List := Choose_Precalculated;
begin
Ada.Text_IO.Put_Line ("Randomly generated:");
Print_Points (My_Circle_Randomly);
Ada.Text_IO.Put_Line ("Chosen from precalculated:");
Print_Points (My_Circle_Precalculated);
end Circle;</lang>
Output:
Randomly generated:
**
* * * *
* * * **
* * * *
** * * *
* * * *
* * * *
* **
* * *
*
* *
* * *
* * *
*
* * *
*
* *
*** *
* * *
*
* *
** *
**
* * ** *
* * * *
*** * * **
* * * ***
* *
Chosen from precalculated:
*
* * *
* ** ** ** *
* * * *
*
* ** * *
* * * *
* * ***
* *** *
* * *
*
* * *
* **
*
* ** ***
*
* *
* **
* *
*
* *
** *
* * * * * *
** * * * *
* **
*
* * ***
ALGOL 68
- note: This specimen retains the original C coding style.
<lang algol68>PROC clrscr = VOID:
printf(($g"[2J"$,REPR 27)); # ansi.sys #
PROC gotoxy = (INT x,y)VOID:
printf(($g"["g(0)";"g(0)"H"$,REPR 27, y,x)); # ansi.sys #
MODE POINT = STRUCT(
INT x,y
);
INT radius = 15; INT inside radius = 10;
POINT center = (radius+1, radius+1);
FLEX[0]POINT set;
PROC swap with last set = (INT position,INT where last set)VOID: (
INT temp := x OF set[position];
x OF set[position]:=x OF set[where last set];
x OF set[where last set] := temp;
temp := y OF set[position];
y OF set[position]:=y OF set[where last set];
y OF set[where last set] := temp
);
PROC create set = VOID: (
set := HEAP[(2*radius+1)**2]POINT;
INT x,y,i:=LWB set;
FOR x FROM -radius TO radius DO
FOR y FROM -radius TO radius DO
IF sqrt(x*x+y*y)>=inside radius AND sqrt(x*x+y*y)<=radius THEN
x OF set[i] := x;
y OF set[i] := y;
i+:=1
FI
OD
OD;
set:=set[:i-1]
);
PROC plot fuzzy set = (CHAR ch)VOID: (
INT pos,i;
TO UPB set DO
pos := ENTIER(random * UPB set) + 1;
gotoxy(x OF center + x OF set[pos],y OF center + y OF set[pos]);
print(ch);
swap with last set(pos,UPB set)
OD
);
main: (
# srand((INT)time(NIL)); #
clrscr;
create set;
plot fuzzy set("*");
gotoxy(2*radius+1, 2*radius+1);
newline(stand in)
)</lang> Sample output:
* * **
* * * * ** **
***** ** ***** **
** ** * * * * ***
* ******** *** *** *
** ***** ** * ***
* ***** *
** ** **** *
* * * ****
**** * ****
* ** *** *
** ** **
** * * *
**** ** *
** * ****
**** ** *
* ** * **
* ** * *
* *** * *
****** * * **
* * ** **** *
** * *** *
**** ** * **
** *** * ***
* * *** * ** *** ***
* * ** ***** ****
** ******* * *
* ** ** *******
* ****** *
*
AutoHotkey
Requires the GDI+ standard library by tic: http://www.autohotkey.com/forum/viewtopic.php?t=32238
Works with individual pixels.
<lang AHK>z=100 ; x = x-coord; y = y-coord; z = count; pBitmap = a pointer to the image; f = filename
pToken := Gdip_Startup() pBitmap := Gdip_CreateBitmap(31, 32)
While z { Random, x, -20, 20 Random, y, -20,20 If ( t := sqrt(x**2 + y**2) ) >= 10 && t <= 15 Gdip_SetPixel(pBitmap, x+15, y+16, 255<<24), z-- }
Gdip_SaveBitmapToFile(pBitmap, f := A_ScriptDir "\ahk_fuzzycircle.png") run % f
Gdip_DisposeImage(pBitmap) Gdip_Shutdown(pToken)</lang>
BASIC
BBC BASIC
<lang bbcbasic> MODE 8
ORIGIN 640, 512
FOR i% = 1 TO 1000
x% = RND(31)-16
y% = RND(31)-16
r = SQR(x%^2 + y%^2)
IF r >= 10 IF r <= 15 PLOT x%*2, y%*2
NEXT</lang>
FreeBASIC
Pre calculate and plot 100 points to the console <lang FreeBASIC>'Free Basic version .9
- define Intrange(f,l) int(Rnd*(((l)+1)-(f))+(f))
Type pair
As Integer x,y
End Type
Operator =(a As pair,b As pair) As Integer Return a.x=b.x And a.y=b.y End Operator
Function NotInArray(a() As pair,n As pair) As Integer
For z As Integer=Lbound(a) To Ubound(a)
If a(z)=n Then Return 0
Next z
Return -1
End Function
Redim As pair pts(0) Dim As Integer x,y,counter Do
counter=counter+1
x=IntRange(-20,20)
y=IntRange(-20,20)
var root=Sqr(x*x+y*y)
If 10<= root And root<=15 Then
If NotInArray(pts(),Type<pair>(x,y)) Then
Redim Preserve pts(1 To Ubound(pts)+1)
pts(Ubound(pts))=Type<pair>(x,y)
End If
End If
Loop Until counter=100000
'============== Plot to Console ======================
dim as integer yres=hiword(width) dim as integer xres=loword(width)
- define map(a,b,x,c,d) ((d)-(c))*((x)-(a))/((b)-(a))+(c)
- define _X(num) int( map(0,xres,(num),0,loword(width)))
- define _Y(num) int( map(0,yres,(num),0,hiword(width)))
counter=0 For n As Integer=Lbound(pts) To Ubound(pts)
counter=counter+1 if counter <=100 then var xpos=map(-20,20,pts(n).x,0,xres) var ypos=map(-20,20,pts(n).y,0,yres) locate _Y(ypos),_X(xpos) print "*" end if
Next n
print locate 1,1 Print "Total number of points "; counter print "Total number plotted ";100 print "done" Sleep </lang> Console output:
Total number of points 404
Total number plotted 100
done * *
* * *
* * * * * *
* * * * * * * * * *
* * * * *
* * * * * *
*
* * * * *
* * * * * *
* * * *
* * * * *
* * * * *
* * * * * *
* * *
* * * * * * * *
* * * *
* * * * * * * * * * *
* * * * *
C
<lang C>#include <stdio.h>
- include <stdlib.h>
inline int randn(int m) { int rand_max = RAND_MAX - (RAND_MAX % m); int r; while ((r = rand()) > rand_max); return r / (rand_max / m); }
int main() { int i, x, y, r2; unsigned long buf[31] = {0}; /* could just use 2d array */
for (i = 0; i < 100; ) { x = randn(31) - 15; y = randn(31) - 15; r2 = x * x + y * y; if (r2 >= 100 && r2 <= 225) { buf[15 + y] |= 1 << (x + 15); i++; } }
for (y = 0; y < 31; y++) { for (x = 0; x < 31; x++) printf((buf[y] & 1 << x) ? ". " : " "); printf("\n"); }
return 0; }</lang>Output<lang> . . . .
. . .
. . . .
. . .
. . . . .
. . .
. . .
. .
. .
. .
. .
. . . .
. . .
.
.
. . .
. . .
. . .
. . . .
. . . . .
. .
. . . .
. . . . . . .
. . . .
. . . . . . .
. . . .
.
. </lang>
C#
<lang csharp>using System; using System.Diagnostics; using System.Drawing;
namespace RosettaConstrainedRandomCircle {
class Program
{
static void Main(string[] args)
{
var points = new Point[404];
int i = 0;
for (int y = -15; y <= 15; y++)
for (int x = -15; x <= 15 && i < 404; x++)
{
var c = Math.Sqrt(x * x + y * y);
if (10 <= c && c <= 15)
{
points[i++] = new Point(x, y);
}
}
var bm = new Bitmap(600, 600);
var g = Graphics.FromImage(bm);
var brush = new SolidBrush(Color.Magenta);
var r = new System.Random();
for (int count = 0; count < 100; count++)
{
var p = points[r.Next(404)];
g.FillEllipse(brush, new Rectangle(290 + 19 * p.X, 290 + 19 * p.Y, 10, 10));
}
const string filename = "Constrained Random Circle.png";
bm.Save(filename);
Process.Start(filename);
}
}
}</lang>
C++
<lang cpp>
- include <windows.h>
- include <list>
- include <iostream>
//-------------------------------------------------------------------------------------------------- using namespace std;
//-------------------------------------------------------------------------------------------------- class point { public:
int x, y;
point() { x = y = 0; }
point( int a, int b ) { x = a; y = b; }
void set( int a, int b ) { x = a; y = b; }
}; //-------------------------------------------------------------------------------------------------- class rndCircle { public:
void draw()
{
createPoints(); drawPoints();
}
private:
void createPoints()
{
point pt; for( int x = 0; x < 200; x++ ) { int a, b, c; while( true ) { a = rand() % 31 - 15; b = rand() % 31 - 15; c = a * a + b * b; if( c >= 100 && c <= 225 ) break; } pt.set( a, b ); _ptList.push_back( pt ); }
}
void drawPoints()
{
HDC dc = GetDC( GetConsoleWindow() ); for( list<point>::iterator it = _ptList.begin(); it != _ptList.end(); it++ ) SetPixel( dc, 300 + 10 * ( *it ).x, 300 + 10 * ( *it ).y, RGB( 255, 255, 0 ) );
}
list<point> _ptList;
}; //-------------------------------------------------------------------------------------------------- int main( int argc, char* argv[] ) {
ShowWindow( GetConsoleWindow(), SW_MAXIMIZE ); srand( GetTickCount() ); rndCircle c; c.draw(); system( "pause" ); return 0;
} //-------------------------------------------------------------------------------------------------- </lang>
Clojure
<lang Clojure>(ns rosettacode.circle-random-points
(:import [java.awt Color Graphics Dimension]
[javax.swing JFrame JPanel]))
(let [points (->> (for [x (range -15 16), y (range -15 16) :when (<= 10 (Math/hypot x y) 15)] [(+ x 15) (+ y 15)]) shuffle (take 100))]
(doto (JFrame.) (.add (doto (proxy [JPanel] []
(paint [^Graphics g]
(doseq [[x y] points]
(.fillRect g (* 10 x) (* 10 y) 10 10))))
(.setPreferredSize (Dimension. 310 310))))
(.setResizable false) (.setDefaultCloseOperation JFrame/DISPOSE_ON_CLOSE) .pack .show))</lang>
COBOL
<lang COBOL>
identification division.
program-id. circle.
environment division.
input-output section.
file-control.
select plot-file assign "circle.txt".
data division.
file section.
fd plot-file report plot.
working-storage section.
1 binary.
2 seed pic 9(18).
2 x pic s9(4).
2 y pic s9(4).
2 i pic 9(4).
2 dot-count pic 9(4) value 0.
2 dot-count-save pic 9(4) value 0.
2 temp-points.
3 pic s9(4) occurs 2.
2 xy-table.
3 point-pair occurs 0 to 404 depending dot-count.
4 x-point pic s9(4).
4 y-point pic s9(4).
1 plot-table value all "0".
2 occurs 31.
3 dot pic 9 occurs 31.
1 cur-date-time.
2 yyyymmdd pic 9(8).
2 hh pic 9(2).
2 mm pic 9(2).
2 ss pic 9(2).
1 plot-work.
2 plot-item pic xb occurs 31.
report section.
rd plot.
1 plot-line type de.
2 line plus 1.
3 column is 1 source is plot-work pic x(62).
procedure division.
begin.
perform compute-seed
perform find-all-valid-points
perform shuffle-point-pairs
perform select-100-dots
perform print-dots
stop run
.
find-all-valid-points.
perform varying x from -15 by 1 until x > +15
perform varying y from -15 by 1 until y > +15
if (function sqrt (x ** 2 + y ** 2))
>= 10 and <= 15
then
move 1 to dot (x + 16 y + 16)
add 1 to dot-count
compute x-point (dot-count) = x + 16
compute y-point (dot-count) = y + 16
end-if
end-perform
end-perform
display "Total points: " dot-count
.
shuffle-point-pairs.
move dot-count to dot-count-save
compute i = function random (seed) * dot-count + 1
perform varying dot-count from dot-count by -1
until dot-count < 2
move point-pair (i) to temp-points
move point-pair (dot-count) to point-pair (i)
move temp-points to point-pair (dot-count)
compute i = function random * dot-count + 1
end-perform
move dot-count-save to dot-count
.
select-100-dots.
perform varying i from 1 by 1
until i > 100
compute x = x-point (i)
compute y = y-point (i)
move 2 to dot (x y)
end-perform
.
print-dots.
open output plot-file
initiate plot
perform varying y from 1 by 1 until y > 31
move spaces to plot-work
perform varying x from 1 by 1 until x > 31
if dot (x y) = 2
move "o" to plot-item (x)
end-if
end-perform
generate plot-line
end-perform
terminate plot
close plot-file
.
compute-seed.
unstring function current-date into
yyyymmdd hh mm ss
compute seed =
(function integer-of-date (yyyymmdd) * 86400)
compute seed = seed
+ (hh * 3600) + (mm * 60) + ss
compute seed = function mod (seed 32768)
.
end program circle.
</lang>
o o o
o o o o
o o o o
o o o o o o o
o o o o o o o
o o o o o o o o
o o o o
o o
o o
o o o o
o o
o
o o o
o o
o o o o
o o o
o o o
o
o o o
o o
o
o o o o
o o
o o o
o o o o o
o o o
o o o o o o
o o o
o o o
o
CoffeeScript
<lang coffeescript> NUM_POINTS = 100 MIN_R = 10 MAX_R = 15
random_circle_points = ->
rand_point = ->
Math.floor (Math.random() * (MAX_R * 2 + 1) - MAX_R)
points = {}
cnt = 0
while cnt < 100
x = rand_point()
y = rand_point()
continue unless MIN_R * MIN_R <= x*x + y*y <= MAX_R * MAX_R
points["#{x},#{y}"] = true
cnt += 1
points
plot = (points) ->
range = [-1 * MAX_R .. MAX_R]
for y in range
s =
for x in range
s += if points["#{x},#{y}"] then '*' else ' '
console.log s
plot random_circle_points() </lang>
The output may be a bit distorted, since even monospace fonts take more vertical space per character than horizontal space. <lang> > coffee foo.coffee
** *
* ** * *
* * * *
* ** *
* * * *
* *
*
* *
***
** **** *
* *
* *
**
*
* **
* * *
**
* * **
* *
* *
* *
* *
***
*** * * * * *
*** *
* * * * *
* * *
</lang>
Common Lisp
<lang lisp>(flet ((good-p (x y) (<= 100 (+ (* x x) (* y y)) 255)))
(loop with x with y with cnt = 0
with scr = (loop repeat 31 collect (loop repeat 31 collect " ")) while (< cnt 100) do (when (good-p (- (setf x (random 31)) 15) (- (setf y (random 31)) 15)) (setf (elt (elt scr y) x) "@ ") (incf cnt)) finally (mapc #'(lambda (row) (format t "~{~a~^~}~%" row)) scr)))</lang>
D
This uses std.complex because D built-in complex numbers will be deprecated. <lang d>import std.stdio, std.random, std.math, std.complex;
void main() {
char[31][31] table = ' ';
foreach (immutable _; 0 .. 100) {
int x, y;
do {
x = uniform(-15, 16);
y = uniform(-15, 16);
} while(abs(12.5 - complex(x, y).abs) > 2.5);
table[x + 15][y + 15] = '*';
}
writefln("%-(%s\n%)", table);
}</lang>
- Output:
*
* ** *
* *
** * * ** * *
* * ** *
** ** *
* *
*
* ***
* * *
* * *
* *
* *
** * *
* *
*
*
* *
*
* **
* * *
* * * *
* * **
* * * * * *
** * ** ** *
**
* * * *
**
EchoLisp
Using the plot library. For a greater visual appeal, points are plotted as circles of random radius and color. The resulting image is at [1]. <lang scheme> (lib 'math) (lib 'plot)
![[1]](http://www.echolalie.org/echolisp/images/circle.png){kind=link}
(define (points (n 100) (radius 10) (rmin 10) (rmax 15) (x) (y)) (plot-clear) (plot-x-minmax (- rmax)) (plot-y-minmax( - rmax))
(for [(i n)] (set! x (round (* (random -1) rmax))) (set! y (round (* (random -1) rmax))) #:when (in-interval? (pythagore x y) rmin rmax) ;; add a little bit of randomness : dots color and radius (plot-fill-color (hsv->rgb (random) 0.9 0.9)) (plot-circle x y (random radius))) (plot-edit)) </lang>
Elixir
Algorithm 1: Generate random pairs
<lang elixir>defmodule Random do
defp generate_point(0, _, _, set), do: set
defp generate_point(n, f, condition, set) do
point = {x,y} = {f.(), f.()}
if x*x + y*y in condition and not point in set,
do: generate_point(n-1, f, condition, MapSet.put(set, point)),
else: generate_point(n, f, condition, set)
end
def circle do
f = fn -> :rand.uniform(31) - 16 end
points = generate_point(100, f, 10*10..15*15, MapSet.new)
range = -15..15
for x <- range do
for y <- range do
IO.write if {x,y} in points, do: "x", else: " "
end
IO.puts ""
end
end
end
Random.circle</lang>
Example output:
x
x x xx x
x x x x xxx x
x x x xx x
x x x x x x
xx x
xx x x
xxx
xxx
xxx
x x
x xx
xx x
x
xx
x x x
xx
x x
xx x x x
x x x
x x
x xx xx
x x x
x x x x
x xx x xx
x xx x x
x xx x
x xx
Algorithm 2: Precalculate
<lang elixir>defmodule Constrain do
def circle do
range = -15..15
r2 = 10*10..15*15
all_points = for x <- range, y <- range, x*x+y*y in r2, do: {x,y}
IO.puts "Precalculate: #{length(all_points)}"
points = Enum.take_random(all_points, 100)
Enum.each(range, fn x ->
IO.puts Enum.map(range, fn y -> if {x,y} in points, do: "o ", else: " " end)
end)
end
end
Constrain.circle</lang>
- Example:
Precalculate: 404
o o
o
o o o o o o
o o o o o
o o o o o o o
o o o o
o o o o o
o o o o
o o o o o
o o o
o o o
o o
o o o
o o o o o
o
o o o
o o o o o o
o
o o
o o o
o o o
o o o o o
o o o
o o o o o o o
o o o o o o
o
o o
o o
Euphoria
This program generates the set of 404 possible points in the ring. It randomly chooses 100 pairs from the set. The 100 pairs are a subset of that set because duplicates are discarded. <lang euphoria>include std/console.e
sequence validpoints = {} sequence discardedpoints = {} sequence rand100points = {} atom coordresult integer randindex
--scan for all possible values. store discarded ones in another sequence, for extra reference. for y = -15 to 15 do
for x = -15 to 15 do
coordresult = sqrt( x * x + y * y )
if coordresult >= 10 and coordresult <= 15 then --if it would fall in the ring area
validpoints &= Template:X, y, coordresult --concatenate (add to the end) the coordinate pair x, y and the
-- result into a subsequence of sequence validpoints
else
discardedpoints &= Template:X, y, coordresult --else put it in the discarded sequence
end if
end for
end for
for i = 1 to 100 label "oneofhundred" do --make 100 random coordinate pairs
randindex = rand(length(validpoints) ) --random value from 1 to the number of 3 value subsequences in validpoints (the data)
if length(rand100points) = 0 then --if rand100points sequence is empty, add the first subsequence to it.
rand100points &= {validpoints[randindex]}
else --if it isn't empty, then..
for j = 1 to length(rand100points) do --loop through each "data chunk" in rand100points
if equal(validpoints[randindex], rand100points[j]) = 1 then --if any are the same as the randomly chosen chunk in
retry "oneofhundred" -- validpoints, then retry from one line below the "oneofhundred" loop without incrementing i.
end if --the continue keyword would increment i instead.
end for
rand100points &= {validpoints[randindex]} --length of rand100points isnt 0 and no data chunks match ones that the program
--already picked before, so add this subsequence chunk to rand100points.
end if
end for
for i = 1 to 32 do --32 lines
printf(1,"\n")
for j = 1 to 32 label "xscan" do --32 characters on each line
for k = 1 to length(rand100points) do --for every subsequence in this
if rand100points[k][1]+16 = j and rand100points[k][2]+16 = i then --if the x and y coordinates in the picked points
printf(1, 178) --(adjusted to minimum of 1,1) are at the same place as in the console output grid
continue "xscan" --print a funny character and continue to the next "xscan"
end if
end for
printf(1, 176) --if no picked points were there, print another funny character to represent a blank space
end for
end for
printf(1, "\nNumber of valid coordinate pairs %d :", length(validpoints) ) printf(1, "\nNumber of discarded coordinate pairs : %d", length(discardedpoints) ) printf(1, "\nNumber of randomly picked coordinate pairs : %d\n", length(rand100points) ) any_key()</lang> Output:
░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ ░░░░░░░░░░░░░░░░░▓░░░░░░░░░░░░░░ ░░░░░░░░░░░░░▓░░░░░░░░░░░░░░░░░░ ░░░░░░░░░▓░░░▓▓░▓░░░▓░░░░░░░░░░░ ░░░░░░▓░░░░░░▓░░░▓░░░░░▓░▓░░░░░░ ░░░░░░░░░▓░▓░░░░░░░▓░░▓░░▓▓░░░░░ ░░░▓░░░░▓░▓░░░░░░░░░░░░▓░░░░░░░░ ░░░░░░░░░▓░░░░░░░░░░░▓░░░▓░░░░░░ ░░░░░░░░░░░░░░░░░░░░░░░░▓▓░░▓░░░ ░░░░░░▓▓░░░░░░░░░░░░░░░▓░░░░░░░░ ░░░░░░▓░░░░░░░░░░░░░░░░░░░░░░░░░ ░▓░░▓▓░░░░░░░░░░░░░░░░░░░░░░░▓░░ ░░░░░▓░░░░░░░░░░░░░░░░░░░░░░▓░░░ ░░▓░░░░░░░░░░░░░░░░░░░░░░▓▓▓▓░░░ ░▓░░▓░░░░░░░░░░░░░░░░░░░░░░░░░░░ ░░░░▓░░░░░░░░░░░░░░░░░░░░▓▓▓░▓░░ ░░░▓░░░░░░░░░░░░░░░░░░░░░▓░▓░▓░░ ░▓▓░░░░░░░░░░░░░░░░░░░░░░░▓▓░░░░ ░░░▓░▓░░░░░░░░░░░░░░░░░░░▓░░░░░░ ░░░▓░░░░░░░░░░░░░░░░░░░░░▓░░░▓░░ ░░▓░▓░░░░░░░░░░░░░░░░░░░▓░░░▓░░░ ░░░░░░░▓░░░░░░░░░░░░░░░▓░░░░░░░░ ░░░▓░░░░░░░░░░░░░░░░░░░▓░░░░░░░░ ░░░░░░░░░░░░░░░░░░░░░░░░▓░░░░░░░ ░░░░░░▓░░▓░░░░░░░░░░░▓░▓░░░░░░░░ ░░░░░░░░░░░░░░░░░▓░░░░░░░░░░░░░░ ░░░░░░░▓░░▓░░░░░░░░░░░░▓░░░░░░░░ ░░░░░░░░░░░░░▓░▓▓▓▓░░░▓▓░░░░░░░░ ░░░░░░░░░▓▓░░▓░░▓░░▓▓░░░░░░░░░░░ ░░░░░░░░░░▓░░▓░▓▓▓░░▓░░░░░░░░░░░ ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ Number of valid coordinate pairs 404 : Number of discarded coordinate pairs : 557 Number of randomly picked coordinate pairs : 100 Press Any Key to continue...
Extra EuSDL code : <lang euphoria>
for i = 1 to length(validpoints) do --simple each pixel output to screen surface
dummy=pixelColor(surface,validpoints[i][1]+18,validpoints[i][2]+18,#AA0202FF) --i is index number of each subsequence 'chunk'. --index 1 is x, index 2 is y, inside that chunk.
end for
for i = 1 to length(discardedpoints) do
dummy=pixelColor(surface,discardedpoints[i][1]+18,discardedpoints[i][2]+52,#0202AAFF)
end for
for i = 1 to length(rand100points) do
dummy=pixelColor(surface,rand100points[i][1]+55,rand100points[i][2]+52,#02AA02FF)
end for
dummy=boxColor(surface,0,71,395,111,#232323FF) --background box dummy=stringColor(surface,0,73,sprintf("Number of valid coordinate pairs %d :", length(validpoints) ),#AA0202FF)
dummy=stringColor(surface,0,83,sprintf("Number of discarded coordinate pairs : %d", length(discardedpoints) ),#0202AAFF)
dummy=stringColor(surface,0,93,sprintf("Number of randomly picked coordinate pairs : %d", length(rand100points) ),#02AA02FF)</lang>SDL Output :
That particular program used a -16 to +16 square area, so more was discarded.
F#
This version uses method 1 from the task description and just calculates 100 suitable points to plot. The INTERACTIVE bit just permits this code in a .fsx file to be run with the interactive interpreter or compiled to an exe. <lang fsharp>module CirclePoints =
let main args =
let rnd = new System.Random()
let rand size = rnd.Next(size) - size/2
let size = 30
let gen n =
let rec f (x,y) =
let t = (int (sqrt (float (x*x + y*y)) ))
if 10 <= t && t <= 15 then (x,y) else f (rand size, rand size)
f (rand size, rand size)
let plot = Array.init 100 (fun n -> gen n)
for row in 0 .. size-1 do
let chars = Array.create (size+1) ' '
Array.choose (fun (x,y) -> if y = (row-size/2) then Some(x) else None) plot
|> Array.iter (fun x -> chars.[x+size/2] <- 'o')
printfn "%s" (new string(chars))
0
- if INTERACTIVE
CirclePoints.main fsi.CommandLineArgs
- else
[<EntryPoint>] let main args = CirclePoints.main args
- endif</lang>
An example of the output:
o o oo
o o
o o o o
o o o oo o o o o
o o
o oo oooo
o oo
o o
oo o
oooo o o
o o
o
o
o oo
o o
o
o
o
o
oo oo o
o
o o o o
o o o
o o o oo
oo o oo o
o o o o
o o o oo o
o o
Factor
<lang factor>USING: io kernel math.matrices math.order math.ranges math.statistics math.vectors random sequences strings ;
CHAR: X -15 15 [a,b] dup cartesian-product concat [ sum-of-squares 100 225 between? ] filter 100 sample [ 15 v+n ] map 31 31 32 <matrix> [ matrix-set-nths ] keep [ >string print ] each</lang>
- Output:
XX X X
XX XXX X X X
X XXX
XX X X
X X XX X X X
X X X
X X X XXXX
X X X XXX
XXX
X
XXX XX
X XX
X
X X
X
X X
X
XXX X
X X
XX X
XX X
XX X X
X X
XXX X X
X X XX XX
X X XX X XX
X X
Falcon
<lang falcon> // Generate points in [min,max]^2 with constraint function random_point (min, max, constraint)
[x, y] = [random(min, max), random(min, max)] return constraint(x, y) ? [x, y] : random_point(min, max, constraint)
end
// Generate point list in_circle = { x, y => 10**2 <= x**2 + y**2 and x**2 + y**2 <= 15**2 } points = [].comp([0:100], {__ => random_point(-15, 15, in_circle)})
// Show points for i in [-15:16]
for j in [-15:16] >> [i, j] in points ? "x" : " " end >
end </lang> Example output:
xxx x
xx x x xx
x xx xx
x x x x x x x x
x x
xx x x
x x x
xx
x x xx
x x
x x
x xx
x
xx
x xx
x xx x
x
xx x xx
xx x x
x x
x x x x
x x x
x x x x x x
x x
x x x x
Fortran
<lang fortran>program Constrained_Points
implicit none integer, parameter :: samples = 100 integer :: i, j, n, randpoint real :: r type points integer :: x, y end type
type(points) :: set(500), temp
! Create set of valid points
n = 0
do i = -15, 15
do j = -15, 15
if(sqrt(real(i*i + j*j)) >= 10.0 .and. sqrt(real(i*i + j*j)) <= 15.0) then
n = n + 1
set(n)%x = i
set(n)%y = j
end if
end do
end do
! create 100 random points ! Choose a random number between 1 and n inclusive and swap point at this index with point at index 1 ! Choose a random number between 2 and n inclusive and swap point at this index with point at index 2 ! Continue in this fashion until 100 points have been selected
call random_seed do i = 1, samples call random_number(r) randpoint = r * (n + 1 - i) + i temp = set(i) set(i) = set(randpoint) set(randpoint) = temp end do
! In order to facilitate printing sort random points into ascending order ! sort x in ascending order
do i = 2, samples
j = i - 1
temp = set(i)
do while (j>=1 .and. set(j)%x > temp%x)
set(j+1) = set(j)
j = j - 1
end do
set(j+1) = temp
end do
! sort y in ascending order for same x
do i = 2, samples
j = i - 1
temp = set(i)
do while (j>=1 .and. set(j)%x == temp%x .and. set(j)%y > temp%y)
set(j+1) = set(j)
j = j - 1
end do
set(j+1) = temp
end do
! print circle
write(*,"(a,a)", advance="no") repeat(" ", set(1)%y+15), "*"
do i = 2, samples
if(set(i)%x == set(i-1)%x) then
write(*,"(a,a)", advance="no") repeat(" ", set(i)%y - set(i-1)%y-1), "*"
else
n = set(i)%x - set(i-1)%x
do j = 1, n
write(*,*)
end do
write(*,"(a,a)", advance="no") repeat(" ", set(i)%y+15), "*"
end if
end do
end program</lang> Output
* *
* * *
** ** * ** *
**
* ** * ** *
*** ** *
* * *
*
* * *
** *
* *
* * *
* *
*
** *** *
* *
** *
* *
* *
* * *
** * *
* * * **
** * * *
*
*** * * *
** * * *
* * * *
* * ** *
*
Frink
<lang frink>g = new graphics
count = 0 do {
x = random[-15,15]
y = random[-15,15]
r = sqrt[x^2 + y^2]
if 10 <= r and r <= 15
{
count = count + 1
g.fillEllipseCenter[x,y,.3, .3]
}
} while count < 100
g.show[]</lang>
gnuplot
<lang gnuplot>
- Ring of random points 2/18/17 aev
reset fn="RingRandPntsGnu"; ttl="Ring of random points" ofn=fn.".png"; lim=1000; randgp(top) = floor(rand(0)*top) set terminal png font arial 12 size 640,640 set output ofn set title ttl font "Arial:Bold,12" unset key; set size square set parametric set xrange [-20:20]; set yrange [-20:20]; set style line 1 lt rgb "red" $rring << EOD EOD set print $rring append do for [i=1:lim] {
x=randgp(30); y=randgp(30);
r=sqrt(x**2+y**2);
if (r>=10&&r<=15) \
{print x," ",y; print -x," ",-y;print x," ",-y; print -x," ",y;}
} plot [0:2*pi] sin(t)*10,cos(t)*10, sin(t)*15,cos(t)*15 ls 1,\ $rring using 1:2 with points pt 7 ps 0.5 lc "black" set output unset print </lang>
- Output:
File: RingRandPntsGnu.png
Go
Algorithm 1: <lang go>package main
import (
"bytes" "fmt" "math/rand" "time"
)
const (
nPts = 100 rMin = 10 rMax = 15
)
func main() {
rand.Seed(time.Now().Unix())
span := rMax + 1 + rMax
rows := make([][]byte, span)
for r := range rows {
rows[r] = bytes.Repeat([]byte{' '}, span*2)
}
u := 0 // count unique points
min2 := rMin * rMin
max2 := rMax * rMax
for n := 0; n < nPts; {
x := rand.Intn(span) - rMax
y := rand.Intn(span) - rMax
// x, y is the generated coordinate pair
rs := x*x + y*y
if rs < min2 || rs > max2 {
continue
}
n++ // count pair as meeting condition
r := y + rMax
c := (x + rMax) * 2
if rows[r][c] == ' ' {
rows[r][c] = '*'
u++
}
}
for _, row := range rows {
fmt.Println(string(row))
}
fmt.Println(u, "unique points")
}</lang> Algorithm 2: <lang go>package main
import (
"bytes" "fmt" "math/rand" "time"
)
const (
nPts = 100 rMin = 10 rMax = 15
)
func main() {
rand.Seed(time.Now().Unix())
var poss []struct{ x, y int }
min2 := rMin * rMin
max2 := rMax * rMax
for y := -rMax; y <= rMax; y++ {
for x := -rMax; x <= rMax; x++ {
if r2 := x*x + y*y; r2 >= min2 && r2 <= max2 {
poss = append(poss, struct{ x, y int }{x, y})
}
}
}
fmt.Println(len(poss), "possible points")
span := rMax + 1 + rMax
rows := make([][]byte, span)
for r := range rows {
rows[r] = bytes.Repeat([]byte{' '}, span*2)
}
u := 0
for n := 0; n < nPts; n++ {
i := rand.Intn(len(poss))
r := poss[i].y + rMax
c := (poss[i].x + rMax) * 2
if rows[r][c] == ' ' {
rows[r][c] = '*'
u++
}
}
for _, row := range rows {
fmt.Println(string(row))
}
fmt.Println(u, "unique points")
}</lang>
- Output:
404 possible points
* * *
* * *
* * * * *
* * * * * * *
* * * * * * *
* * *
* * * * *
* * * *
* * * * *
*
* * *
* * *
* *
* * *
*
* *
* * *
* *
*
* *
* * *
* *
* * * * * * *
* * * *
* * * *
* * *
*
*
90 unique points
Haskell
Using Knuth Shuffle <lang haskell>import Data.List import Control.Monad import Control.Arrow import Rosetta.Knuthshuffle
task = do
let blanco = replicate (31*31) " "
cs = sequence [[-15,-14..15],[-15,-14..15]] :: Int
constraint = uncurry(&&).((<= 15*15) &&& (10*10 <=)). sum. map (join (*))
-- select and randomize all circle points
pts <- knuthShuffle $ filter constraint cs
-- 'paint' first 100 randomized circle points on canvas
let canvas = foldl (\cs [x,y] -> replaceAt (31*(x+15)+y+15) "/ " cs ) blanco (take 100 pts)
-- show canvas
mapM_ (putStrLn.concat). takeWhile(not.null). unfoldr (Just . splitAt 31) $ canvas</lang>
Output (added a trailing space per 'pixel'
*Main> task
/ / /
/ / /
/ /
/ / / / / / /
/ / / /
/ / / / /
/ / /
/ / / / /
/ / / / / /
/
/ / /
/ / /
/ / /
/
/ / / /
/ /
/ /
/
/ /
/ /
/ /
/ / /
/ / / / /
/ / / /
/ / / / / / /
/ / / /
/ /
/ / / / / / / /
/ / /
Hy
<lang lisp>(import
[math [sqrt]] [random [choice]] [matplotlib.pyplot :as plt])
(setv possible-points (list-comp (, x y)
[x (range -15 16) y (range -15 16)] (<= 10 (sqrt (+ (** x 2) (** y 2))) 15)))
(setv [xs ys] (apply zip (list-comp (choice possible-points) [_ (range 100)])))
; We can't use random.sample because that samples without replacement.
(plt.plot xs ys "bo") (plt.show)</lang>
Icon and Unicon
Generate random points in the bounded by the outside edge. Reject any found out of the prescribed bounds and stop when the required numbers of points have been generated.
<lang Icon>link graphics
procedure main(A) # points, inside r, outside r in pixels - default to task values
if \A[1] == "help" then stop("Usage: plot #points inside-radius outside-radius") points := \A[1] | 100 outside := \A[2] | 15 inside := \A[3] | 10 if inside > outside then inside :=: outside
wsize := integer(2.2*outside) wsize <:= 150 center := wsize/2
WOpen("size="||wsize||","||wsize,"bg=black","fg=white") | stop("Unable to open window")
until(points -:= 1) <= 0 do {
x := ?(2*outside)-outside # random x
y := ?(2*outside)-outside # and y
if (inside <= integer(sqrt(x^2+y^2)) ) <= outside then
DrawPoint(x + center,y + center)
}
WDone()
end</lang>
J
This version deals 100 distinct coordinates from the set of acceptable coordinates (much like dealing cards from a shuffled deck):
<lang j>gen=: ({~ 100?#)bind((#~ 1=99 225 I.+/"1@:*:),/,"0/~i:15)</lang>
Example use (gen'' generates the points, the rest of the example code deals with rendering them as a text array):
<lang j> '*' (<"1]15+gen )} 31 31$' '
*
*
* * * * * *
* * * * *
* ***
** * * **
* **
* **
* * * *
* * **
* ** **
** * ***
* ** * *
** *
* ** *
** *
* ** *
* *
* *
* *
** *
* **
*
* * * *
* ** * * *
* *
**
* * *
** * </lang>
Java
<lang java>import java.util.Random;
public class FuzzyCircle { static final Random rnd = new Random(); public static void main(String[] args){ char[][] field = new char[31][31]; for(int i = 0; i < field.length; i++){ for(int j = 0; j < field[i].length; j++){ field[i][j] = ' '; } } int pointsInDisc = 0; while(pointsInDisc < 100){ int x = rnd.nextInt(31) - 15; int y = rnd.nextInt(31) - 15; double dist = Math.hypot(x, y); if(dist >= 10 && dist <= 15 && field[x + 15][y + 15] == ' '){ field[x + 15][y + 15] = 'X'; pointsInDisc++; } } for(char[] row:field){ for(char space:row){ System.out.print(space); } System.out.println(); } } }</lang> Output:
XX X
X X X X X
X XX X
XXXX X X
X X X XXX
X X
X X XXX
X X
X X XX
X X X
XX X
X
X X
XXXXX X X
X X
X X
X X
X X X
X X
XX X
XX X
X XX X
X XX X
X X X X X
XX X X XXX
X X X X XX
X X
X
X
JavaScript
JavaScript embedded in HTML, using canvas: <lang javascript><html><head><title>Circle</title></head> <body> <canvas id="cv" width="320" height="320"></canvas> <script type="application/javascript">
var cv = document.getElementById('cv'); var ctx = cv.getContext('2d');
var w = cv.width; var h = cv.height;
//draw circles ctx.fillStyle = 'rgba(0, 255, 200, .3)'; ctx.strokeStyle = 'rgba(0,0,0,.1)'; ctx.beginPath(); ctx.arc(w/2, h/2, 150, 0, Math.PI*2, true); ctx.arc(w/2, h/2, 100, 0, Math.PI*2, false); ctx.closePath(); ctx.fill();
// draw grids ctx.beginPath(); for (var i = 10; i < w; i += 10) { ctx.moveTo(i, 0); ctx.lineTo(i, h); ctx.moveTo(0, i); ctx.lineTo(w, i); } ctx.closePath(); ctx.stroke();
//draw points ctx.fillStyle = 'navy'; var pts = 0; while (pts < 100) { var x = Math.floor(Math.random() * 31) - 15; var y = Math.floor(Math.random() * 31) - 15; var r = x * x + y * y; if (r < 100 || r > 225) continue; x = x * 10 + w/2; y = y * 10 + h/2; ctx.fillRect(x - 2, y - 2, 4, 4); pts++; }
</script></body></html></lang>
Julia
This solution uses the "pick random x, y and cull" rather than the "calculate valid and choose randomly" approach. <lang julia>function printcircle(lo::Integer, hi::Integer, ndots::Integer; pad::Integer = 2)
canvas = falses(2hi + 1, 2hi + 1)
i = 0
while i < ndots
x, y = rand(-hi:hi, 2)
if lo ^ 2 - 1 < x ^ 2 + y ^ 2 < hi ^ 2 + 1
canvas[x + hi + 1, y + hi + 1] = true
i += 1
end
end
# print
for i in 1:(2hi + 1)
row = map(j -> j ? "\u25cf " : " ", canvas[i, :])
println(" " ^ pad, join(row))
end
return canvas
end
printcircle(10, 15, 100)</lang>
- Output:
● ●
● ● ● ● ●
● ● ● ●
● ● ● ●
● ● ● ●
● ●
● ● ●
● ● ●
● ●
● ● ● ●
● ●
●
● ● ● ● ●
● ●
● ● ●
●
● ● ●
● ●
● ●
● ● ● ● ●
● ● ● ●
●
● ● ● ● ●
● ● ● ● ● ● ● ● ● ●
● ● ● ● ● ●
● ● ●
● ●
● ●
Kotlin
<lang scala>// version 1.1.3
fun main(args: Array<String>) {
val r = java.util.Random()
val points = Array(31) { CharArray(31) { ' ' } }
var count = 0
while (count < 100) {
val x = r.nextInt(31) - 15
val y = r.nextInt(31) - 15
val h = x * x + y * y
if (h in 100..225) {
points[x + 15][y + 15] = 'o'
count++
}
}
for (i in 0..30) println(points[i].joinToString(""))
}</lang>
Sample output:
ooo oo o
o
oo oo
o oo o
o ooo oo
o oo
o o o
o o oo o
o o
o o
o ooo
o oo
o oo
o o
o o o
o o
o ooo
o o o
o
oo o oo
oo o
o o o
ooo o
oo o
o o o
oo o o
o o
o o
Liberty BASIC
<lang lb>' RC Constrained Random Points on a Circle
nomainwin
WindowWidth =400 WindowHeight =430
open "Constrained Random Points on a Circle" for graphics_nsb as #w
- w "trapclose [quit]"
- w "down ; size 7 ; color red ; fill black"
for i =1 to 1000
do
x =int( 30 *rnd( 1)) -15
y =int( 30 *rnd( 1)) -15
loop until IsInRange( x, y) =1
#w "set "; 200 +10 *x; " "; 200 - 10 *y
next
wait
function IsInRange( x, y)
z =sqr( x*x +y*y) if 10 <=z and z <=15 then IsInRange =1 else IsInRange =0
end function
[quit] close #w end</lang>
Locomotive Basic
<lang locobasic>10 MODE 1:RANDOMIZE TIME 20 FOR J=1 TO 100 30 X=INT(RND*30-15) 40 Y=INT(RND*30-15) 50 D=X*X+Y*Y 60 IF D<100 OR D>225 THEN GOTO 40 70 PLOT 320+10*X,200+10*Y:LOCATE 1,1:PRINT J 80 NEXT 90 CALL &BB06 ' wait for key press</lang>
Maple
<lang maple> a := table():
i := 1: while i < 100 do ba := (rand(-15 .. 15))(): bb := (rand(-15 .. 15))(): b := evalf(sqrt(ba^2+bb^2)): if b <= 15 and b >= 10 then a[i] := [ba, bb]: i := i+1: end if: end do: plots:-pointplot(convert(a,list));</lang>
Mathematica / Wolfram Language
This algorithm generates 500 pairs of random integers between +/- 15, picks out the ones that satisfy the inequality, and then takes the first 100 of those. It oversamples to reduce the chance of having less than 100 "candidates", which is not impossible, though extremely unlikely. <lang Mathematica>sample = Take[Cases[RandomInteger[{-15, 15}, {500, 2}], {x_, y_} /; 10 <= Sqrt[x^2 + y^2] <= 15], 100];
Show[{RegionPlot[10 <= Sqrt[x^2 + y^2] <= 15, {x, -16, 16}, {y, -16, 16}, Axes -> True], ListPlot[sample]}]</lang>
MATLAB
Uses the Monte-Carlo method described above.
<lang MATLAB>function [xCoordinates,yCoordinates] = randomDisc(numPoints)
xCoordinates = []; yCoordinates = [];
%Helper function that samples a random integer from the uniform
%distribution between -15 and 15.
function nums = randInt(n)
nums = round((31*rand(n,1))-15.5);
end
n = numPoints;
while n > 0
x = randInt(n);
y = randInt(n);
norms = sqrt((x.^2) + (y.^2));
inBounds = find((10 <= norms) & (norms <= 15));
xCoordinates = [xCoordinates; x(inBounds)];
yCoordinates = [yCoordinates; y(inBounds)];
n = numPoints - numel(xCoordinates);
end
xCoordinates(numPoints+1:end) = [];
yCoordinates(numPoints+1:end) = [];
end</lang>
Output:
<lang MATLAB>>> [x,y] = randomDisc(100);
>> plot(x,y,'.')</lang>
Maxima
<lang Maxima>randomDisc(numPoints):= block([p: []],
local(goodp, random_int),
goodp(x, y):=block([r: sqrt(x^2+y^2)],
r>=10 and r<=15
),
random_int():= block([m: 15], m - random(2*(m+1)-1)),
while length(p)<numPoints do block (
[x: random_int(), y : random_int()],
if goodp(x, y) then (
p: cons([x, y], p)
)
),
p)$
p: randomDisc(100)$ plot2d(['discrete, p], ['style, 'points]);</lang>
Nim
<lang nim>import tables, math, strutils, complex, random
proc random[T](a: openarray[T]): T =
result = a[rand(low(a)..len(a))]
type Point = tuple[x, y: int]
var world = initCountTable[Point]() var possiblePoints = newSeq[Point]()
for x in -15..15:
for y in -15..15:
if abs((x.float, y.float)) in 10.0..15.0:
possiblePoints.add((x,y))
randomize() for i in 0..100: world.inc possiblePoints.random
for x in -15..15:
for y in -15..15:
let key = (x, y)
if key in world and world[key] > 0:
stdout.write min(9, world[key])
else:
stdout.write ' '
echo ""</lang>
Output:
1
1211 1
1 1 3 1 1
3 11
1 11 1 1 1
122 21 1
1 1 2
1
1 1
11 11
1 1 1
1
11 1
1 1 11
2 1
1
1 1
1 1
11
11
1 1 111
1 1 1 1
1 11
1 1 1
12 2 11 1 1
1 1 1 1 1
11 1
1
OCaml
<lang ocaml>let p x y =
let d = sqrt(x ** 2.0 +. y ** 2.0) in 10.0 <= d && d <= 15.0
let () =
Random.self_init();
let rec aux i acc =
if i >= 100 then acc else
let x = (Random.float 40.0) -. 20.0
and y = (Random.float 40.0) -. 20.0 in
if (p x y)
then aux (succ i) ((x,y)::acc)
else aux i acc
in
let points = aux 0 [] in
let g = Array.init 40 (fun _ -> String.make 40 ' ') in
List.iter (fun (x,y) ->
let x = (int_of_float x) + 20
and y = (int_of_float y) + 20 in
g.(y).[x] <- 'o'
) points;
Array.iter print_endline g</lang>
o o o
o
oo oo oooo
o o oo o
oo
o o o
o
oo o
oo o oo o
oo
oo
o o
oooo o o
oo o o
o oo
o
o o o o
o o o o
o o
o o
o o oo
o oo
o o
ooo o o o
o ooo o
o
oo o
PARI/GP
<lang parigp>crpc()={
my(v=vector(404),t=0,i=0,vx=vy=vector(100));
for(x=1,14,for(y=1,14,
t=x^2+y^2;
if(t>99&t<226,
v[i++]=[x,y];
v[i++]=[x,-y];
v[i++]=[-x,y];
v[i++]=[-x,-y]
)
));
for(x=10,15,
v[i++]=[x,0];
v[i++]=[-x,0];
v[i++]=[0,x];
v[i++]=[0,-x]
);
for(i=1,#vx,
t=v[random(#v)+1];
vx[i]=t[1];
vy[i]=t[2];
);
plothraw(vx,vy)
};</lang>
Perl
Graphical output
<lang perl>my @points; while (@points < 100) {
my ($x, $y) = (int(rand(31))-15, int(rand(31)) - 15);
my $r2 = $x*$x + $y*$y;
next if $r2 < 100 || $r2 > 225;
push @points, [$x, $y];
}
print << 'HEAD'; %!PS-Adobe-3.0 EPSF-3.0 %%BoundingBox 0 0 400 400 200 200 translate 10 10 scale 0 setlinewidth 1 0 0 setrgbcolor 0 0 10 0 360 arc stroke 0 0 15 360 0 arcn stroke 0 setgray /pt { .1 0 360 arc fill } def HEAD
print "@$_ pt\n" for @points; print "%%EOF";</lang>
Randomly generates points and reject ones not in the ring. Writes an EPS file.
Plain-text output
<lang perl>@range = -15..16;
for $x (@range) {
for $y (@range) {
$radius = sqrt $x**2 + $y**2;
push @points, [$x,$y] if 10 <= $radius and $radius <= 15
}
}
push @sample, @points[int rand @points] for 1..100; push @matrix, ' ' x @range for 1..@range; substr $matrix[15+$$_[1]], 15+$$_[0], 1, '*' for @sample; print join(' ', split , $_) . "\n" for @matrix;</lang>
- Output:
* * *
* * *
* * *
* *
* * * *
* *
* * * *
* * *
* *
* *
* * * * * * *
*
* * *
*
* * * *
* *
* * *
* * *
* * * *
* * *
* * * *
* *
* *
* * * *
* * * * *
* * * * *
* *
*
Phix
<lang Phix>sequence screen = repeat(repeat(' ',31),31) integer x, y, count = 0 atom r while 1 do
x = rand(31)
y = rand(31)
r = sqrt(power(x-16,2)+power(y-16,2))
if r>=10 and r<=15 then
screen[x][y] = 'x'
count += 1
if count>=100 then exit end if
end if
end while puts(1,join(screen,"\n"))</lang>
- Output:
x xx
x x x
x x x x x
x x x x
x x xx
x x x x
xx xx x
x
x
x
x x
x
x x x
xx xxxx
x x
x x
x
x x x
x
x x
xx x x x
x x
x x x
x x x x
x x xx x
x x x xx xx
xx x
x xx
x x x
PicoLisp
<lang PicoLisp>(let Area (make (do 31 (link (need 31 " "))))
(use (X Y)
(do 100
(until
(>=
15
(sqrt
(+
(* (setq X (rand -15 15)) X)
(* (setq Y (rand -15 15)) Y) ) )
10 ) )
(set (nth Area (+ 16 X) (+ 16 Y)) "#") ) )
(mapc prinl Area) )</lang>
Output:
#
##
# # # #
## # # # #
# # # # #
# # # # #
# # # #
# # #
#
# #
## #
#
# # #
### #
# # #
## # #
# #
# #
## #
#
#
# #
#
### # #
### # # #
# #
# # ##
# #
# # #
# # #
PL/I
version 1
<lang PL/I> constrain: procedure options (main);
declare 1 point (100),
2 x fixed binary,
2 y fixed binary;
declare (i, j, a, b, c) fixed binary;
j = 0;
do i = 1 to 100;
a = 30*random()-15; b = 30*random()-15;
c = sqrt(a**2 + b**2);
if abs(c) >= 10 & abs(c) <= 15 then
do; j = j + 1; x(j) = a; y(j) = b; end;
end;
/* PLOT */
declare table(-15:15, -15:15) character (1);
table = ' ';
do i = 1 to j;
table(x(i), y(i)) = '*';
end;
do i = -15 to 15;
put skip;
do j = -15 to 15;
put edit (table(i,j)) (a);
end;
end;
end constrain; </lang> Output:
** *
* *
**
**
*
***
*
*
**
*
* **
* *
** *
* *
***
***
***
*
*
version 2
<lang PL/I>*process source attributed xref or(!);
annulus: procedure options (main);
/* version 1 does not handle (0/15) etc. this does. */
/* we show 1000 points here */
declare 1 point(10000),
2 x fixed binary,
2 y fixed binary;
declare (i, j, a, b, a2, b2, c) fixed binary(31);
j = 0;
do i = 1 to 1000;
r=rand(31); a=r-16;
r=rand(31); b=r-16;
a2=a*a;
b2=b*b;
c2=a2+b2;
if c2>= 100 & c2 <= 225 then
do; j = j + 1; x(j) = a; y(j) = b;
/* put Edit(a,b,c)(3(F(3))); */ end;
end;
/* PLOT */
declare table(-15:15, -15:15) character (2);
table = ' ';
do i = 1 to j;
table(x(i), y(i)) = '*';
end;
do i = -15 to 15;
put skip;
do j = -15 to 15;
put edit (table(i,j)) (a);
end;
end;
rand: Proc(n) Returns(Bin Fixed(31)); /*-------------------------------------------------------------------- * Return a random integer between 1 and n *-------------------------------------------------------------------*/ Dcl r Bin Float(31); Dcl (n,d) Bin Fixed(31); r=random(); d=r*n+1; Return(d); End; End annulus;</lang>
output
*
* * * * * * *
* * * * * * * * * *
* * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * *
* * * * * * * * *
* * * * * * *
* * * * * * * *
* * * * * * * * *
* * * * *
* * * * * * * *
* * * * * * *
* * * * * * * * *
* * * * *
* * * * * * * * * *
* * * * * *
* * * * * *
* * * * * * *
* * * * * * *
* * * * * * *
* * * * * *
* * * * * * * *
* * * * * * * * * * *
* * * * * * * * * *
* * * * * * * * * * * * * *
* * * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * *
* * * * * *
PowerShell
<lang PowerShell>$MinR2 = 10 * 10 $MaxR2 = 15 * 15
$Points = @{}
While ( $Points.Count -lt 100 )
{
$X = Get-Random -Minimum -16 -Maximum 17
$Y = Get-Random -Minimum -16 -Maximum 17
$R2 = $X * $X + $Y * $Y
If ( $R2 -ge $MinR2 -and $R2 -le $MaxR2 -and "$X,$Y" -notin $Points.Keys )
{
$Points += @{ "$X,$Y" = 1 }
}
}
ForEach ( $Y in -16..16 ) { ( -16..16 | ForEach { ( " ", "*" )[[int]$Points["$_,$Y"]] } ) -join }</lang>
- Output:
***
* ** *
* *** *
* * * ** * *
* * * *
* * *
* * *** *
* *****
** * *
* * ***
** * ***
* * *
*
* * *
*
*
** *
* * **
*
*
* **
* * * *
* * ** *
* ** ** *
* * * * *
*
**
** *
Prolog
Works with SWI-Prolog <lang Prolog>:- use_module(library(clpfd)).
circle :- bagof([X,Y], init(X,Y), BL), length(BL, N), length(L, 100), maplist(choose(BL, N), L), draw_circle(L).
% point selection
choose(BL, N, V) :-
I is random(N),
nth0(I, BL, V).
% to find all couples of numbers verifying % 100 <= x^2 + y^2 <= 225 init(X1, Y1) :- X in -15..15, Y in -15..15, X*X + Y*Y #>= 100, X*X + Y*Y #=< 225, label([X,Y]), X1 is 10 * X + 200, Y1 is 10 * Y + 200.
draw_circle(L) :-
new(D, window('Circle')),
send(D, size,size(400,400)),
forall(member([X,Y], L),
( new(C, circle(4)),
send(C, fill_pattern, colour(@default, 0, 0, 0)),
send(C, center(point(X,Y))),
send(D, display, C))),
send(D, open).
</lang>
PureBasic
<lang PureBasic>CreateImage(0,31,31) StartDrawing(ImageOutput(0))
For i=1 To 100
Repeat
x=Random(30)-15
y=Random(30)-15
R.f=Sqr(x*x+y*y)
Until 10<=R And R<=15
Plot(x+15,y+15,#Red)
Next
StopDrawing()
Title$="PureBasic Plot"
Flags=#PB_Window_SystemMenu
OpenWindow(0,#PB_Ignore,#PB_Ignore,ImageWidth(0),ImageHeight(0),Title$,Flags)
ImageGadget(0,0,0,ImageWidth(0),ImageHeight(0),ImageID(0))
Repeat: Until WaitWindowEvent()=#PB_Event_CloseWindow</lang>
Python
Note that the diagram shows the number of points at any given position (up to a maximum of 9 points). <lang python>>>> from collections import defaultdict >>> from random import choice >>> world = defaultdict(int) >>> possiblepoints = [(x,y) for x in range(-15,16) for y in range(-15,16) if 10 <= abs(x+y*1j) <= 15] >>> for i in range(100): world[choice(possiblepoints)] += 1
>>> for x in range(-15,16): print(.join(str(min([9, world[(x,y)]])) if world[(x,y)] else ' ' for y in range(-15,16)))
1 1
1 1
11 1 1 1 1
111 1 1211
1 2 1 1 11
1 11 21
1 1 11 1
1 2 1 1
1 2
1 1 1
1 1
2 11
1 1
1
1 1
1
2
1
1 1 1
1 2 1
1 3 11 2
11 1 1 1 2
1 1 2
1 1
1 1 1
2 2 1
1 </lang>
If the number of samples is increased to 1100: <lang python>>>> for i in range(1000): world[choice(possiblepoints)] += 1
>>> for x in range(-15,16): print(.join(str(min([9, world[(x,y)]])) if world[(x,y)] else ' ' for y in range(-15,16)))
2
41341421333
5133333131253 1
5231514 14214721 24
326 21222143234122322
54235153132123344125 22
32331432 2422 33
5453135 4144344
132595 323123
4 6353 432224
5 4323 3 5313
23214 41433
42454 33342
332 4 34314
142 1 35 53
124211 53131
22221 152 4
22213 34562
654 4 4 212
24354 52232
544222 283323
411123 453325
251321 124332
2124134 2443226
2 113315 64324334
2412452 324 32121132363
4222434324635 5433
3113333123432112633
2131181233 424
47414232164
4 </lang>
R
<lang R> RMin <- 10 RMax <- 15 NPts <- 100
- instead of a for loop, we generate what should be enough points
- also take care to have enough range to avoid rounding inaccuracies
nBlock <- NPts * ((RMax/RMin) ^ 2) nValid <- 0 while (nValid < NPts) { X <- round(runif(nBlock, -RMax - 1, RMax + 1)) Y <- round(runif(nBlock, -RMax - 1, RMax + 1)) R <- sqrt(X^2 + Y^2) Valid <- ( (R >= RMin) & (R <= RMax) ) nValid <- sum(Valid) nBlock <- 2 * nBlock } plot(X[Valid][1:NPts],Y[Valid][1:NPts], pch=19, cex=0.25, col="blue", xlab="x",ylab="y",main="Fuzzy circle", xlim=c(-RMax,RMax), ylim=c(-RMax,RMax) ) </lang>
Example of solution
Racket
<lang racket>#lang racket
(require plot plot/utils)
(plot (points (for*/lists (result)
([_ (in-naturals)]
#:break (= 100 (length result))
[xy (in-value (v- (vector (random 31) (random 31))
#(15 15)))]
#:when (<= 10 (vmag xy) 15))
xy)))</lang>
Raku
(formerly Perl 6)
<lang perl6>my @range = -15..16;
my @points = gather for @range X @range -> ($x, $y) {
take [$x,$y] if 10 <= sqrt($x*$x+$y*$y) <= 15
} my @samples = @points.roll(100); # or .pick(100) to get distinct points
- format and print
my %matrix; for @range X @range -> ($x, $y) { %matrix{$y}{$x} = ' ' } %matrix{.[1]}{.[0]} = '*' for @samples; %matrix{$_}{@range}.join(' ').say for @range;</lang>
- Output:
*
* *
* * * * *
* * * *
* * * * *
* *
* * *
* * * *
*
* * * *
* * *
* * * *
*
* *
* * *
* * * *
* * *
*
* *
* *
* * *
* * *
* *
* * *
* * * * * * *
* * * * * *
* * * *
* *
* * *
Turning that program completely inside-out and reducing to a single statement with a single non-parameter variable, we get another version that also works.
This uses, among other things, a 0-based matrix rather than a hash, a given on the first line that allows us to print the final value of the matrix straight from its initial declaration, a for statement feeding a for statement modifier, a lambda that unpacks a single x-y argument into two variables, the functional form of pick rather than the method form, a quasi-list comprehension in the middle loop that filters each given with a when, precalculated squared limits so we don't have to take the square root, use of X- and X** to subtract and exponentiate both $x and $y in parallel.
After the given do has loaded up @matrix with our circle, the map on the first line substitutes a space for any undefined matrix element, and the extra space between elements is supplied by the stringification of the list value, performed by the prefix ~ operator, the unary equivalent of concatenation in Raku.
At this point you would be justified in concluding that we are completely mad. :-)
<lang perl6>(say ~.map: { $_ // ' ' } for my @matrix) given do
-> [$x, $y] { @matrix[$x][$y] = '*' } for pick 100, do
for ^32 X ^32 -> ($x, $y) {
[$x,$y] when 100..225 given [+] ($x,$y X- 15) X** 2;
}
</lang>
- Output:
* * *
* * *
* * * * * *
* * * * * *
* * * * * *
* * *
* * * * *
* * * *
* *
* *
*
* * *
* *
* * * * * *
* *
* * * *
* * *
* * * *
* *
* *
* * *
* * * * * *
* * * *
* * * * * *
* * * *
* * * * *
* * *
REXX
version 1
This REXX version uses aspect adjustment for the plot of the (sparse) annulus. <lang rexx>/*REXX program generates 100 random points in an annulus: 10 ≤ √(x²≤y²) ≤ 15 */ parse arg pts LO HI . /*obtain optional args from the C.L. */ if pts== then pts= 100 /*Not specified? Then use the default.*/ if LO== then LO= 10; LO2= LO**2 /*define a shortcut for squaring LO. */ if HI== then HI= 15; HI2= HI**2 /* " " " " " HI. */ $=
do x=-HI; xx= x*x /*generate all possible annulus points.*/
if x>0 & xx>HI2 then leave /*end of annulus points generation ? */
do y=-HI; s= xx + y*y
if (y<0 & s>HI2) | s<LO2 then iterate
if y>0 & s>HI2 then leave
$= $ x','y /*add a point─set to the $ list. */
end /*y*/
end /*x*/
#= words($); @.= /*def: plotchr; #pts; lines*/
do pts; parse value word($, random(1,#)) with x ',' y /*get rand point in annulus*/
@.y= overlay('☼', @.y, x+x + HI+HI + 1) /*put a plot char on a line*/
end /*pts*/ /* [↑] maintain aspect ratio on X axis*/
/*stick a fork in it, we're all done. */
do y=-HI to HI; say @.y; end /*display the annulus to the terminal. */</lang>
- output when using the default inputs:
☼ ☼
☼ ☼ ☼
☼ ☼ ☼ ☼ ☼
☼ ☼ ☼
☼ ☼ ☼ ☼
☼ ☼ ☼
☼ ☼
☼ ☼ ☼
☼ ☼ ☼
☼ ☼ ☼ ☼
☼ ☼ ☼
☼ ☼
☼ ☼
☼ ☼ ☼
☼
☼ ☼ ☼ ☼
☼ ☼
☼ ☼ ☼
☼ ☼ ☼ ☼
☼ ☼ ☼ ☼ ☼
☼ ☼ ☼ ☼
☼ ☼ ☼
☼ ☼ ☼
☼
☼ ☼ ☼ ☼ ☼
☼ ☼ ☼ ☼
☼ ☼ ☼ ☼ ☼
☼ ☼
☼
version 2
<lang rexx>/* REXX ---------------------------------------------------------------
- show 100 random points of an annulus with radius 10 to 15
- 18.06.2014 Walter Pachl 'derived/simplified' from REXX version 1
- --------------------------------------------------------------------*/
Parse Arg points low high scale . /* allow parms from command line.*/
If points== Then points=100 /* number of points */
If low== Then low=10 /* inner radius */
If high== Then high=15 /* outer radius */
If scale== Then scale=2 /* horizontal scaling */
low2=low**2
high2=high**2
/* first compute all possible points */
point.=0
Do x=-high To high
x2=x*x
Do y=-high To high
y2=y*y
s=x2+y2
If s>=low2 &s<=high2 Then Do
z=point.0+1
point.z=x y
point.0=z
End
End
End
plotchar='O'
line.=
np=point.0 /* available points */
Do j=1 To points /* pick the needed points */
r=random(1,np)
Parse Var point.r x y /* coordinates */
line.y=overlay(plotchar,line.y,scale*(x+high)+1) /* put into line*/
point.r=point.np /* replace taken point by last*/
np=np-1 /* reduce available points */
If np=0 Then Leave /* all possible points taken */
End
/* now draw the picture */
Do y=-high To high Say line.y End</lang>
output using default parameters
O
O O O
O O O O O
O O O O O O O O O
O O O O O O O O
O O O O O O O
O O
O
O O
O O
O
O O O O O
O O O
O
O O O
O
O
O
O O
O O O O
O O O
O O O O O
O O O O O
O O
O O O O O
O O
O O O O O O O O O
O O O O O
O O
output using rexx fcaa 100 3 4 2
O
O O O O O
O O
O O
O O O O
O O
O O
O O O O O
O
version 3
<lang rexx>/* REXX ---------------------------------------------------------------
- 19.06.2014 Walter Pachl alternate algorithm
- the idea: yl is a list of y coordinates which may have unused points
- one of the y's is picked at random
- Then we look for unused x coordinates in this line
- we pick one at random or drop the y from yl if none is found
- When yl becomes empty, all points are used and we stop
- --------------------------------------------------------------------*/
Parse Arg n r rr scale If r= Then r=10 If rr= Then rr=15 If n= Then n=100 If scale= Then scale=2 r2=r*r rr2=rr*rr ymin=0 ymax=rr*2 ol= pp.=0 used.=0 yl= /* list of available y values */ Do y=-rr To rr
yl=yl y End
Do Until pp.0=n /*look for the required points*/
If yl= Then Do /* no more points available */
Say 'all points filled'
Leave
End
yi=random(1,words(yl)) /* pick a y */
y=word(yl,yi)
y2=y*y
p.=0
Do x=0 To rr /* Loop through possible x's */
x2=x*x
xy2=x2+y2
If xy2>=r2&xy2<=rr2 Then Do /* within the annulus */
Call take x y
Call take (-x) y
End
End
If p.0>0 Then Do /* some x's found (or just 1) */
xi=random(1,p.0) /* pick an x */
z=pp.0+1
pp.z=p.xi
pp.0=z
Parse Var pp.z xa ya
used.xa.ya=1 /* remember it's taken */
End
Else Do /* no x for this y */
yi=wordpos(y,yl) /* remove y from yl */
Select
When yi=1 Then yl=subword(yl,yi+1)
When yi=words(yl) Then yl=subword(yl,1,yi-1)
Otherwise yl=subword(yl,1,yi-1) subword(yl,yi+1)
End
End
End
line.= /* empty the raster */ Do i=1 To pp.0 /* place the points */
Parse Var pp.i x y
line.y=overlay('+',line.y,scale*(rr+x)+1)
End
Do y=-rr To rr /* show the result */
Say line.y End
say pp.0 'points filled' Exit Return
take: Procedure Expose p. used. /* add x to p. if its not used*/
Parse Arg x y If used.x.y=0 Then Do z=p.0+1 p.z=x y p.0=z End Return</lang>
output using rexx fcaa 100 3 5 2
all points filled
+
+ + + + + + +
+ + + + + + + + +
+ + + +
+ + + +
+ + + + + +
+ + + +
+ + + +
+ + + + + + + + +
+ + + + + + +
+
56 points filled
Ring
<lang ring> load "guilib.ring"
new qapp
{
win1 = new qwidget() {
setwindowtitle("drawing using qpainter")
setgeometry(100,100,500,500)
label1 = new qlabel(win1) {
setgeometry(10,10,400,400)
settext("")
}
new qpushbutton(win1) {
setgeometry(200,400,100,30)
settext("draw")
setclickevent("draw()")
}
show()
}
exec()
}
func draw
p1 = new qpicture()
color = new qcolor() {
setrgb(0,0,255,255)
}
pen = new qpen() {
setcolor(color)
setwidth(1)
}
new qpainter() {
begin(p1)
setpen(pen)
for i = 1 to 1000
x = random(31)-16
y = random(31)-16
r = sqrt (pow(x,2) + pow(y,2))
if r >= 10 if r <= 15 drawpoint(x*2, y*2) ok ok
next
endpaint()
}
label1 { setpicture(p1) show() }
</lang>
Output:
Ruby
Create the image with Raster graphics operations/Ruby <lang Ruby>points = (1..100).map do
# choose a random radius and angle angle = rand * 2.0 * Math::PI rad = rand * 5.0 + 10.0 # convert back from polar to cartesian coordinates [rad * Math::cos(angle), rad * Math::sin(angle)].map(&:round)
end
(-15..15).each do |row|
puts (-15..15).map { |col| points.include?([row, col]) ? "X" : " " }.join
end
load 'raster_graphics.rb'
pixmap = Pixmap.new(321,321) pixmap.draw_circle(Pixel.new(160,160),90,RGBColour::BLACK) pixmap.draw_circle(Pixel.new(160,160),160,RGBColour::BLACK) points.each {|(x,y)| pixmap[10*(x+16),10*(y+16)] = RGBColour::BLACK} pngfile = __FILE__ pngfile[/\.rb/] = ".png" pixmap.save_as_png(pngfile)</lang>
- Output:
X X
X XX
X XXX
XX X X X X X
XXXXX
XX XX
X X X
X X
X X
X X XXX
X
XX X X
X X
X X
XXX X
XX X
XXX X X
XX X X X
XX X X
X X
X
XX X X
X X X
X X X
X
X X X
X X X
X X
algorithm 2:
<lang ruby>r2 = 10*10..15*15 range = (-15..15).to_a points = range.product(range).select {|i,j| r2.cover?(i*i + j*j)}
puts "Precalculate: #{points.size}" pt = Hash.new(" ") points.sample(100).each{|ij| pt[ij] = " o"} puts range.map{|i| range.map{|j| pti,j}.join}</lang>
- Output:
Precalculate: 404
o o o
o o o o
o o o o o
o o o o o o
o o o o o
o o
o o
o o o
o o o
o o o o
o o
o
o
o o
o o o
o
o o o o o
o o o
o o o o
o
o o o
o o o
o o o o o o
o o o o o o o o o
o o o o o
o o o o o o
o o o o o
o o
o
Run BASIC
<lang runbasic>w = 320 h = 320 dim canvas(w,h) for pts = 1 to 1000
x = (rnd(1) * 31) - 15 y = (rnd(1) * 31) - 15 r = x * x + y * y if (r > 100) and (r < 225) then x = int(x * 10 + w/2) y = int(y * 10 + h/2) canvas(x,y) = 1 end if
next pts
' ----------------------------- ' display the graphic ' ----------------------------- graphic #g, w,h for x = 1 to w
for y = 1 to h
if canvas(x,y) = 1 then #g "color green ; set "; x; " "; y else #g "color blue ; set "; x; " "; y
next y
next x render #g
- g "flush"</lang>
Rust
<lang Rust>#![feature(inclusive_range_syntax)]
extern crate rand;
use rand::Rng;
const POINTS_N: usize = 100;
fn generate_point<R: Rng>(rng: &mut R) -> (i32, i32) {
loop {
let x = rng.gen_range(-15, 16); // exclusive
let y = rng.gen_range(-15, 16);
let r2 = x * x + y * y;
if r2 >= 100 && r2 <= 225 {
return (x, y);
}
}
}
fn filtering_method<R: Rng>(rng: &mut R) {
let mut rows = [[" "; 62]; 31];
// Generate points
for _ in 0..POINTS_N {
let (x, y) = generate_point(rng);
rows[(y + 15) as usize][(x + 15) as usize * 2] = "*";
}
// draw the points
for row in &rows {
println!("{}", row.concat());
}
}
fn precalculating_method<R: Rng>(rng: &mut R) {
// Generate all possible points
let mut possible_points = Vec::with_capacity(404);
for y in -15..=15 {
for x in -15..=15 {
let r2 = x * x + y * y;
if r2 >= 100 && r2 <= 225 {
possible_points.push((x, y));
}
}
}
// A truncated Fisher-Yates shuffle
let len = possible_points.len();
for i in (len - POINTS_N..len).rev() {
let j = rng.gen_range(0, i + 1);
possible_points.swap(i, j);
}
// turn the selected points into "pixels"
let mut rows = [[" "; 62]; 31];
for &(x, y) in &possible_points[len - POINTS_N..] {
rows[(y + 15) as usize][(x + 15) as usize * 2] = "*";
}
// draw the "pixels"
for row in &rows {
println!("{}", row.concat());
}
}
fn main() {
let mut rng = rand::weak_rng();
filtering_method(&mut rng);
precalculating_method(&mut rng);
}</lang>
Scala
<lang Scala>import java.awt.{ Color, geom,Graphics2D ,Rectangle}
import scala.math.hypot import scala.swing.{MainFrame,Panel,SimpleSwingApplication} import scala.swing.Swing.pair2Dimension import scala.util.Random
object CirculairConstrainedRandomPoints extends SimpleSwingApplication {
//min/max of display-x resp. y val dx0, dy0 = 30; val dxm, dym = 430 val prefSizeX, prefSizeY = 480
val palet = Map("b" -> Color.blue, "g" -> Color.green, "r" -> Color.red, "s" -> Color.black)
val cs = List((0, 0, 10, "b"), (0, 0, 15, "g")) //circle position and color
val xmax, ymax = 20; val xmin, ymin = -xmax
class Coord(x: Double, y: Double) {
def dx = (((dxm - dx0) / 2 + x.toDouble / xmax * (dxm - dx0) / 2) + dx0).toInt
def dy = (((dym - dy0) / 2 - y.toDouble / ymax * (dym - dy0) / 2) + dy0).toInt
}
object Coord {
def apply(x: Double, y: Double) = new Coord(x, y)
}
//points:
val points =
new Iterator[Int] { val r = new Random;def next = r.nextInt(31) - 15; def hasNext = true }.toStream.
zip(new Iterator[Int] { val r = new Random; def next = r.nextInt(31) - 15; def hasNext = true }.toStream).
map { case (x, y) => (x, y, hypot(x, y)) }.filter { case (x, y, r) => r >= 10 && r <= 15 }.take(100).toSeq.
map { case (x, y, r) => new Rectangle(Coord(x, y).dx - 2, Coord(x, y).dy - 2, 4, 4) }
private def ui = new Panel {
background = Color.white
preferredSize = (prefSizeX, prefSizeY)
class Circle(center: Coord, r: Double, val color: Color) {
val dr = (Coord(r, 0).dx - pcentre.dx) * 2
val dx = center.dx - dr / 2
val dy = center.dy - dr / 2
}
object Circle {
def apply(x: Double, y: Double, r: Double, color: Color) =
new Circle(Coord(x, y), r, color)
}
val pcentre = Coord(0, 0) val pxmax = Coord(xmax, 0); val pxmin = Coord(xmin, 0) val pymax = Coord(0, ymax); val pymin = Coord(0, ymin)
//axes: val a_path = new geom.GeneralPath a_path.moveTo(pxmin.dx, pxmin.dy); a_path.lineTo(pxmax.dx, pxmax.dy) //x-axis a_path.moveTo(pymin.dx, pymin.dy); a_path.lineTo(pymax.dx, pymax.dy) //y-axis
//labeling:
val labels = List(-20, -15, -10, -5, 5, 10, 15, 20)
labels.foreach { x => { val p = Coord(x, 0); a_path.moveTo(p.dx, p.dy - 3); a_path.lineTo(p.dx, p.dy + 3) } }
labels.foreach { y => { val p = Coord(0, y); a_path.moveTo(p.dx - 3, p.dy); a_path.lineTo(p.dx + 3, p.dy) } }
val xlabels = labels.map(x => { val p = Coord(x, 0); Triple(x.toString, p.dx - 3, p.dy + 20) })
val ylabels = labels.map(y => { val p = Coord(0, y); Triple(y.toString, p.dx - 20, p.dy + 5) })
//circles:
val circles = cs.map { case (x, y, r, c) => Circle(x, y, r, palet(c)) }
override def paintComponent(g: Graphics2D) = {
super.paintComponent(g)
circles.foreach { c => { g.setColor(c.color); g.drawOval(c.dx, c.dy, c.dr, c.dr) } }
g.setColor(palet("r")); points.foreach(g.draw(_))
g.setColor(palet("s")); g.draw(a_path)
xlabels.foreach { case (text, px, py) => g.drawString(text, px, py) }
ylabels.foreach { case (text, px, py) => g.drawString(text, px, py) }
}
} // def ui
def top = new MainFrame {
title = "Rosetta Code >>> Task: Constrained random points on a circle | Language: Scala"
contents = ui
}
}</lang>
Sidef
Generates an EPS file. <lang ruby>var points = []; while (points.len < 100) {
var (x, y) = 2.of{31.rand.int - 15}...;
var r2 = (x**2 + y**2);
if ((r2 >= 100) && (r2 <= 225)) {
points.append([x, y]);
}
}
print <<'HEAD'; %!PS-Adobe-3.0 EPSF-3.0 %%BoundingBox 0 0 400 400 200 200 translate 10 10 scale 0 setlinewidth 1 0 0 setrgbcolor 0 0 10 0 360 arc stroke 0 0 15 360 0 arcn stroke 0 setgray /pt { .1 0 360 arc fill } def HEAD
points.each { |pt| say "#{pt.join(' ')} pt" }; print '%%EOF';</lang>
Standard ML
Works with PolyML. Plotting function from 'Draw a pixel' task. Uniform random generator: copy from Random_numbers#Standard_ML. x,y plotted scaled x 10 px <lang Standard ML>open XWindows ; open Motif ;
val plotWindow = fn coords => (* input list of int*int within 'dim' *) let
val dim = {tw=325,th=325} ;
val shell = XtAppInitialise "" "demo" "top" [] [ XmNwidth (#tw dim), XmNheight (#th dim) ] ; (* single call only *)
val main = XmCreateMainWindow shell "main" [ XmNmappedWhenManaged true ] ;
val canvas = XmCreateDrawingArea main "drawarea" [ XmNwidth (#tw dim), XmNheight (#th dim) ] ;
val usegc = DefaultGC (XtDisplay canvas) ;
val put = fn (w,s,t)=> (
XSetForeground usegc 0xfffffff ;
XFillRectangle (XtWindow canvas) usegc (Area{x=0,y=0,w = #tw dim, h= #th dim}) ;
XSetForeground usegc 0 ;
XDrawPoints (XtWindow canvas) usegc ( List.map (fn (x,y)=>XPoint {x=x,y=y}) coords ) CoordModeOrigin ;
t ) in
( XtSetCallbacks canvas [ (XmNexposeCallback , put) ] XmNarmCallback ; XtManageChild canvas ; XtManageChild main ; XtRealizeWidget shell )
end;
val urandomlist = fn seed => fn n => (* put code from (www.rosettacode.org) wiki/Random_numbers#Standard_ML 'urandomlist' here input : seed and number of drawings *) end;
val normalizedPts = fn () => (* select ([0,1]*[0,1]) points in normalized bandwidth *)
let val realseeds = ( 972.1 , 10009.3 ) ; val usum = fn (u,v) => u*(u-1.0) + v*(v-1.0) ; val lim = ( ~350.0/900.0, ~225.0/900.0 ) ; (* limits to usum *) val select = fn i => usum i <= #2 lim andalso usum i >= #1 lim ; (* select according to inequalities *) val uv = ListPair.zip ( urandomlist (#1 realseeds) 2500 , urandomlist (#2 realseeds) 2500 ) (* take 2500 couples *) in List.take ( List.filter select uv , 1000 )
end ;</lang> call
> val scaledXY = map (fn (x,y)=>
( Real.toInt IEEEReal.TO_NEAREST (10.0+300.0*x), Real.toInt IEEEReal.TO_NEAREST (10.0+300.0*y) )) (normalizedPts ()) ;
> plotWindow scaledXY ;
Swift
<lang swift>let nPoints = 100
func generatePoint() -> (Int, Int) {
while true {
let x = Int.random(in: -15...16)
let y = Int.random(in: -15...16)
let r2 = x * x + y * y
if r2 >= 100 && r2 <= 225 {
return (x, y)
}
}
}
func filteringMethod() {
var rows = String(repeating: Array(repeating: " ", count: 62), count: 31)
for _ in 0..<nPoints {
let (x, y) = generatePoint()
rows[y + 15][x + 15 * 2] = "*" }
for row in rows {
print(row.joined())
}
}
func precalculatingMethod() {
var possiblePoints = [(Int, Int)]()
for y in -15...15 {
for x in -15...15 {
let r2 = x * x + y * y
if r2 >= 100 && r2 <= 225 {
possiblePoints.append((x, y))
}
}
}
possiblePoints.shuffle()
var rows = String(repeating: Array(repeating: " ", count: 62), count: 31)
for (x, y) in possiblePoints {
rows[y + 15][x + 15 * 2] = "*"
}
for row in rows {
print(row.joined())
}
}
print("Filtering method:") filteringMethod()
print("Precalculating method:") precalculatingMethod()</lang>
- Output:
Filtering method:
*
** *
** ** *
* ** * *
** * *
* ** **
* *
*
* ** *
* *
* * * ***
*
* * *
**
* *
* *
*
* * *
*
* **
*
* * *
* *
*
** **
* **
*** * *
* ** * *
* *
* * *
*
Precalculating method:
*
***********
***************
*******************
*********************
***********************
******** ********
******* *******
****** ******
****** ******
****** ******
***** *****
***** *****
***** *****
***** *****
****** ******
***** *****
***** *****
***** *****
***** *****
****** ******
****** ******
****** ******
******* *******
******** ********
***********************
*********************
*******************
***************
***********
*
SystemVerilog
<lang SystemVerilog>program main;
bit [39:0] bitmap [40];
class Point; rand bit signed [4:0] x; rand bit signed [4:0] y;
constraint on_circle_edge {
(10*10) <= (x*x + y*y);
(x*x + y*y) <= (15*15);
};
function void do_point();
randomize;
bitmap[x+20][y+20] = 1;
endfunction
endclass
initial begin Point p = new; repeat (100) p.do_point; foreach (bitmap[row]) $display( "%b", bitmap[row]); end
endprogram</lang>
Piping the output through sed to improve the contrast of the output:
% vcs -sverilog -R circle.sv | sed 's/0/ /g'
1
11 1 1
1 1 1 11
1 1 1 11
1 1 1
1 1 1
1
1 1 1
1 1 1
1
11
11
1
11 1 1 1
1 1
1 1 1 1
1 1 1
11 1 1
11
1111 1
1 111 1
11 1 111 1
11
1 1
1 1 1
1
1 11
1
1 1
11 1 1
Tcl
<lang tcl>package require Tcl 8.5
- Generate random point at specified distance from the centre
proc getPoint {range from to} {
set r2 [expr {$range / 2}]
set f2 [expr {$from ** 2}]
set t2 [expr {$to ** 2}]
while 1 {
set x [expr {int($range * rand())}] set y [expr {int($range * rand())}] set d2 [expr {($x-$r2)**2 + ($y-$r2)**2}] if {$d2 >= $f2 && $d2 <= $t2} { return [list $y $x] }
}
}
- Make somewhere to store the counters
set ary [lrepeat 31 [lrepeat 31 0]]
- Generate 100 random points
for {set i 0} {$i < 100} {incr i} {
set location [getPoint 31 10 15]
# Increment the counter for the point
lset ary $location [expr {1 + [lindex $ary $location]}]
}
- Simple renderer
foreach line $ary {
foreach c $line {
puts -nonewline [expr {$c == 0 ? " " : $c > 9 ? "X" : $c}]
} puts ""
}</lang> Example output:
1
1 1
1 1 1 2 1 1
11 1 1 1
11 1 1 1
1 1
1 12 1
1 1 1
1 1 1
1 1
1 1 1
1 2
1
1 1
2 1 2
2 1
1
1 11
1 1
1
1 1
2 1 1
1 1
1 1 1 11 1
2 1 1 11
11 1 1 1
1 2 1 11
121 1 1
1 1 1
1
XPL0
<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations int X, Y, C, R2; [SetVid($13); \set 320x200x8 graphics mode C:= 0; \initialize point counter repeat X:= Ran(31)-15; \range -15..+15
Y:= Ran(31)-15;
R2:= X*X + Y*Y;
if R2>=10*10 & R2<=15*15 then
[Point(X+160, Y+100, $F); C:= C+1];
until C >= 100; C:= ChIn(1); \wait for keystroke SetVid(3); \restore normal text mode ]</lang>
zkl
<lang zkl>xy:=(0).walker(*).tweak(fcn{ // generate infinite random pairs (lazy)
x:=(-15).random(16); y:=(-15).random(16); if(not (100<=(x*x + y*y)<=225)) Void.Skip else T(x,y)
});
const N=31; // [-15..15] includes 0 array:=(" ,"*N*N).split(",").copy(); // bunch of spaces (list)
xy.walk(100).apply2(fcn([(x,y)],array){array[x+15 + N*(y+15)]="*"},array); foreach n in ([0..30]){ array[n*N,30].concat().println(); }</lang>
- Output:
* * *
** ***
* * * ** *
* **
* * * *
* * *
* * ***
*
* *
* * * *
* *
* *
*
* *
**** **
*
*
* *
* *
** * *
* *
* * *
* *
* *
** * **
* * ***
* * *
* *
*
ZX Spectrum Basic
<lang zxbasic>10 FOR i=1 TO 1000 20 LET x=RND*31-16 30 LET y=RND*31-16 40 LET r=SQR (x*x+y*y) 50 IF (r>=10) AND (r<=15) THEN PLOT 127+x*2,88+y*2 60 NEXT i</lang>
- Programming Tasks
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- Standard ML
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- SystemVerilog
- Tcl
- XPL0
- Zkl
- ZX Spectrum Basic