Hello; hoping someone can help me because i'm somewhat puzzled...I'm a relative Perl newbie...

I have a multidimensional array which is pulling arrays of three elements from a file that is a list of three-number lines.

In other words, I'm taking a file that looks like:

1 2 20
2 3 15
3 4 3
4 5 17
5 6 28
6 1 23
1 7 1
2 7 4
3 7 9
4 7 16
5 7 25
6 7 36

[download]

And producing an array structured like:

my @item_array = {{1, 2, 20}, {2, 3, 15}, {3,4,3}, {4, 5, 17}, {5,6,28}, {6,1,23}, {1, 7, 1}, {2, 7, 4}, {3, 7, 9,}, {4, 7, 16}, {5, 7, 25}, {6, 7, 36}};

All of this is written and works. I'd now like to sort @item_array by the third element in each sub array (i.e. {2, 3, 15} should come before {1, 2, 20}, etc.).

I found code which I think should do this:

my @sorted_array = sort { $a->[2] <=> $b->[2] } @item_array;

However, when I print this out, it seems that all it's doing is turning all of the sub arrays into the last sub array. In other words, @sorted_array is just twelve instances of {6, 7, 36}.

Does anyone have any idea why this is happening? What would the proper code be to sort this array by the third element of each child array?

In reply to Sort multidimensional array by third item by rosalindwills

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.