G'day ibm1620,

I think what you're looking for is splice.

Test script:

#!/usr/bin/env perl

use v5.36;
use constant {
    AREF    => 0,
    PYTHON  => 1,
    EXP     => 2,
};

use Test::More;

my @test_array = 'a' .. 'g';

my @tests = (
    [\@test_array, '[:3]',  'abc'],
    [\@test_array, '[:-3]', 'abcd'],
    [\@test_array, '[3:]',  'defg'],
    [\@test_array, '[-3:]', 'efg'],
);

plan tests => 0+@tests;

for my $test (@tests) {
    is get_array_slice_by_python_expr($test->@[AREF, PYTHON]),
        $test->[EXP], "Testing: $test->[PYTHON]";
}

sub get_array_slice_by_python_expr ($aref, $python) {
    state $re = qr{^\[(|-?\d+):(|-?\d+)\]$};
    my @temp_array = $aref->@*;
    my ($offset, $length) = $python =~ $re;
    $offset ||= 0;

    return length($length)
           ? join('', splice @temp_array, $offset, $length)
           : join('', splice @temp_array, $offset);
}

[download]

Output:

1..4
ok 1 - Testing: [:3]
ok 2 - Testing: [:-3]
ok 3 - Testing: [3:]
ok 4 - Testing: [-3:]

[download]

— Ken

In reply to Re: Converting python list range expressions to perl by kcott
in thread Converting python list range expressions to perl by ibm1620

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.