>-----Original Message----- >From: Rick Triplett [mailto:r...@reason.net] >Sent: Tuesday, October 13, 2009 12:09 PM >To: Perl Beginners >Subject: Sorting mixed alphanumerics > >I need to sort the keys in a hash. The keys are the question number >and the values are the student's answer. A numeric sort with <=> won't >work since retaking a missed question (say, 2) produces the new key, >2h with its new answer. A representative hash might look like this > >1 => b >2h => c >3 => a >2 => a > >I chose the sort routine > >{$a <=> $b || $a cmp $b} > >which sorts correctly but gives me a warning about the occasional "h" >not being numeric. I could suppress warnings for the sort routine or >for the whole code, but I'd rather write better code, code that >doesn't produce a warning. Unfortunately I haven't been able to figure >out the correct code, despite looking through the sort sections of the >standard books on Perl. Even though I'm a Perl novice, my intuition >tells me that there is probably a simple way to do this. But several >days of experimenting have been unsuccessful. >
I don't know if this is the simple way. http://www.stonehenge.com/merlyn/UnixReview/col64.html http://en.wikipedia.org/wiki/Schwartzian_transform use strict; use warnings; my %results = ( '1' => 'b', '2h' => 'c', '3' => 'a', '2' => 'a', ); print "question $_ answer $results{$_}\n" for map { $_->[0] } sort { $a->[1] <=> $b->[1] || $a->[2] cmp $b->[2] } map { [ $_, /^(\d+)(\D+|$)/ ] } keys %results; question 1 answer b question 2 answer a question 2h answer c question 3 answer a >Advice appreciated! > >Rick Triplett > >-- >To unsubscribe, e-mail: beginners-unsubscr...@perl.org >For additional commands, e-mail: beginners-h...@perl.org >http://learn.perl.org/ > Regards, Scott Hall Columbia MEIS Bose Corporation -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
