Kernighans large earthquake problem

Kernighans large earthquake problem is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based.

Problem

You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event.

Example lines from the file would be lines like:

8/27/1883    Krakatoa            8.8
5/18/1980    MountStHelens       7.6
3/13/2009    CostaRica           5.1

Task

1. Create a program or script invocation to find all the events with magnitude greater than 6
2. Assuming an appropriate name e.g. "data.txt" for the file:
   1. Either: Show how your program is invoked to process a data file of that name.
   2. Or: Incorporate the file name into the program, (as it is assumed that the program is single use).

AWK

<lang awk> awk '$3 > 6' data.txt</lang>

Kotlin

<lang scala>// Version 1.2.40

import java.io.File

fun main(args: Array<String>) {

   val r = Regex("""\s+""")
   println("Those earthquakes with a magnitude > 6.0 are:\n")
   File("data.txt").forEachLine {
       if (it.split(r)[2].toDouble() > 6.0) println(it)
   }    

}</lang>

Output:

Using the given file:

Those earthquakes with a magnitude > 6.0 are:

8/27/1883    Krakatoa            8.8
5/18/1980    MountStHelens       7.6

Perl

<lang perl>perl -n -e '/(\S+)\s*$/ and $1 > 6 and print' data.txt</lang>

Perl 6

Works with: Rakudo version 2018.03

Pass in a file name, or use default for demonstration purposes. <lang perl6>$_ = @*ARGS[0].IO // q:to/END/;

   8/27/1883    Krakatoa            8.8
   5/18/1980    MountStHelens       7.6
   3/13/2009    CostaRica           5.1
   END

map { .say if .words[2] > 6 }, .lines;</lang>

>

Python

Typed into a bash shell or similar: <lang python>python -c ' with open("data.txt") as f:

   for ln in f:
       if float(ln.strip().split()[2]) > 6:
           print(ln.strip())'</lang>