> The Perl code works but compared to the Python version it looks a little bit awkward.

The question is if you want it fast or pretty.

Without extra modules, this doesn't look particular awkward to me. 

use strict;
use warnings;

my $PCHR = "KQRBNP";
my $w1   = "QRKPNB";
my $w2 =
  join "",
  sort { index ($PCHR, $a) <=> index ($PCHR, $b) }
  split //, $w1;

print "$w1 -> $w2";

[download]

of course it's far more efficient to store the index in a hash, which in turn needs to be precalculated.

Others have shown you external "sort_by" implementations using so-called "key-functions" like in Python ( That's when you can avoid to repeat code for $a and $b).

But I'm not sure if these key-functions - in Python or CPAN - actually cache the results for performance optimization in a hash. (This might be too clever if a key function is supposed to vary results)

Which brings us back to the question: fast or pretty?

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re: Sort list by position of items in another list by LanX
in thread Sort list by position of items in another list by gflohr

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