|
let c = [| for n = 1 to 10 do yield n |] // lazy array
let d = [| "hello"; "world" |] // array of strings
==[[Groovy]]==
Follows the pattern of the fascinating Fortran example above:
Arrays and lists are synonymous in Groovy. They can be initialized with a wide range of operations and Groovy enhancements to the Collection and List classes.
<lang groovy>def aa = [ 1, 25, 31, -3 ] // list
def a = [0] * 100 // list of 100 zeroes
def b = 1..9 // range notation
def c = (1..10).collect { 2.0**it } // each output element is 2**(corresponding invoking list element)
// There are no true "multi-dimensional" arrays in Groovy (as in most C-derived languages).
// Use lists of lists in natural ("row major") order as a stand in.
def d = (0..1).collect { i -> (1..5).collect { j -> 2**(5*i+j) as double } }
def e = [ [ 1.0, 2.0, 3.0, 4.0 ],
[ 5.0, 6.0, 7.0, 8.0 ],
[ 9.0, 10.0, 11.0, 12.0 ],
[ 13.0, 14.0, 15.0, 16.0 ] ]
println aa
println b
println c
println()
d.each { print "["; it.each { elt -> printf "%7.1f ", elt }; println "]" }
println()
e.each { print "["; it.each { elt -> printf "%7.1f ", elt }; println "]" }</lang>
Output:
<pre>[1, 25, 31, -3]
[1, 2, 3, 4, 5, 6, 7, 8, 9] ▼[2, 4, 8, 16, 32, 64, 128, 256, 512, 1024]
[ 2.0 4.0 8.0 16.0 32.0 ]
[ 64.0 128.0 256.0 512.0 1024.0 ]
[ 1.0 2.0 3.0 4.0 ]
[ 5.0 6.0 7.0 8.0 ]
[ 9.0 10.0 11.0 12.0 ]
[ 13.0 14.0 15.0 16.0 ]</pre>
Here is a more interesting example showing a function that creates and returns a square identity matrix of order N:
<lang groovy>def identity = { n ->
(1..n).collect { i -> (1..n).collect { j -> i==j ? 1.0 : 0.0 } }
}</lang>
Test program:
<lang groovy>def i2 = identity(2)
def i15 = identity(15)
i2.each { print "["; it.each { elt -> printf "%4.1f ", elt }; println "]" }
println()
i15.each { print "["; it.each { elt -> printf "%4.1f ", elt }; println "]" }</lang>
Output:
<pre>[ 1.0 0.0 ]
[ 0.0 1.0 ]
[ 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 ]
[ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 ]</pre>
==[[Haskell]]==
array ((0,0),(5,5)) [((0,0),0),((0,1),0),((0,2),0),((0,3),0),((0,4),0),((0,5),0),((1,0),0),((1,1),0),((1,2),0),((1,3),0),((1,4),0),((1,5),0),((2,0),0),((2,1),0),((2,2),0),((2,3),0),((2,4),0),((2,5),0),((3,0),0),((3,1),0),((3,2),0),((3,3),0),((3,4),0),((3,5),0),((4,0),0),((4,1),0),((4,2),0),((4,3),0),((4,4),0),((4,5),0),((5,0),0),((5,1),0),((5,2),0),((5,3),0),((5,4),0),((5,5),0)]
</lang>
=={{header|Scala}}==
<lang Scala>// immutable maps
var map = Map(1 -> 2, 3 -> 4, 5 -> 6)
map(3) // 4
map = map + (44 -> 99) // maps are immutable, so we have to assign the result of adding elements
map.isDefinedAt(33) // false
map.isDefinedAt(44) // true</lang>
<lang scala>// mutable maps (HashSets)
import scala.collection.mutable.HashMap
val hash = new HashMap[Int, Int]
hash(1) = 2
hash += (1 -> 2) // same as hash(1) = 2
▲[1,hash 2,+= (3 , -> 4, 5 , -> 6, 7,44 8,-> 9]99)
hash(44) // 99
hash.contains(33) // false
hash.isDefinedAt(33) // same as contains
hash.contains(44) // true</lang>
<lang scala>// iterate over key/value
hash.foreach {e => println("key "+e._1+" value "+e._2)} // e is a 2 element Tuple
// same with for syntax
for((k,v) <- hash) println("key " + k + " value " + v)</lang>
<lang scala>// items in map where the key is greater than 3
map.filter {k => k._1 > 3} // Map(5 -> 6, 44 -> 99)
// same with for syntax
for((k, v) <- map; if k > 3) yield (k,v)</lang>
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