Hello melmoth, and welcome to the Monastery!

I don’t know about the “cleanest” way, but delete works nicely:

#! perl
use strict;
use warnings;
use Data::Dump;

my %HASH;
$HASH{keyA}{keyB} = [1 .. 4];
dd \%HASH;

my $array_ref = $HASH{keyA}{keyB};

delete $HASH{keyB};
delete $HASH{keyA};

$HASH{keyB}{keyA} = $array_ref;
dd \%HASH;

[download]

Output:

23:53 >perl 1360_SoPW.pl
{ keyA => { keyB => [1 .. 4] } }
{ keyB => { keyA => [1 .. 4] } }

23:53 >

[download]

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re: inverting keys in a 2-D Hash by Athanasius
in thread inverting keys in a 2-D Hash by melmoth

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.