Sorting numbers in Raku with the help of ChatGPT

In this post I will show you the solution to the Task 2 of this week’s Weekly Challenge 233. This time I was using the help of ChatGPT, which offered a very nice solution.

You are given an array of integers.
Write a script to sort the given array in increasing order based on the frequency of the values. If multiple values have the same frequency then sort them in decreasing order.

I asked ChatGPT the following: ‘Create a program. Here is the description of the task.’ To make sure the result is in the Raku programming language, I also added the following instruction in my local settings so that it knows which programming language I prefer by default.

The solution generated by ChatGPT was quite good with a small mistake.

ChatGPT: Sure, here’s a Raku program that implements the described sorting algorithm for the given task:

sub frequency-sort(@arr) { my %freq; %freq{$_}++ for @arr; my @sorted = @arr.sort: { %freq{$^b} <=> %freq{$^a} || $^b <=> $^a }; return @sorted; } my @ints = (1, 1, 2, 2, 2, 3); my @sorted = frequency-sort(@ints); say "Input: @ints"; say "Output: @sorted"; 

First, Raku would not interpolate arrays, so say "Input: @ints" prints the string literary: Input: @ints. Second, in the sorting rule, sorting by frequency must be ascending rather than descending, so we need to switch the placeholder variables $^b and $^a.

In the rest, ChatGPT did a good work. It computed the frequency using a loop, and I especially liked how it addressed the requirement to sort by two dimensions.

Here is the full program with the above-mentioned corrections:

sub frequency-sort(@arr) { my %freq; %freq{$_}++ for @arr; my @sorted = @arr.sort: { %freq{$^a} <=> %freq{$^b} || $^b <=> $^a }; return @sorted; } my @tests = (1, 1, 2, 2, 2, 3), (2, 3, 1, 3, 2), (-1, 1, -6, 4, 5, -6, 1, 4, 1); say frequency-sort($_) for @tests; 

This program prints the following output for the given test cases:

$ raku ch-2.raku [3 1 1 2 2 2] [1 3 3 2 2] [5 -1 4 4 -6 -6 1 1 1]