populating a HoA with regexp


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populating a HoA with regexp

by asqwerty (Novice)

on Aug 28, 2012 at 13:45 UTC ( #990249=perlquestion: print w/ replies, xml )

Need Help??

asqwerty has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

I have a file with a single column of words like this:

brain0001
lung0001
brain00002
kidney0003
brain00003
[download]

I need to put this words into a hash of arrays, separated by its category (brain, lung, kidney), so I wrote this code:

$data = "mydata.list";

@pref = ("brain", "lung", "kidney");

%dfs = map {$_ => ()} @pref;

open DF, "<$data";
while(my $line=<DF>){
    chomp($line);
    foreach $pat (@pref){
        push @{$dfs{$pat}},$line if ($line=~/$pat/);
    }
}
close DF;
[download]

This code actually works and populate the hash in the right way. However, I think the foreach loop can be replaced with a single line.

How can I do this?

Comment on populating a HoA with regexp Select or Download Code
Re: populating a HoA with regexp by Anonymous Monk on Aug 28, 2012 at 13:50 UTC
I call mine uiop `#!/usr/bin/perl -- use strict; use warnings; use Data::Dump; open my($DF), '<', \q{ brain0001 lung0001 brain00002 kidney0003 brain00003 }; my %dfs; while( <$DF> ){ chomp; /^(brain\|lung\|kidney)/ and push @{$dfs{$1}}, $_; } close $DF; dd \%dfs; __END__ { brain => ["brain0001", "brain00002", "brain00003"], kidney => ["kidney0003"], lung => ["lung0001"], }` [download]	[reply] [d/l]
Re: populating a HoA with regexp by BrowserUk (Pope) on Aug 28, 2012 at 13:55 UTC
You could do this: `#! perl -slw use strict; use Data::Dump qw[ pp ]; my %dfs; m[([a-z]+)(\d+)] and push @{ $dfs{ $1 } }, $2 while <DATA>; pp \%dfs; __DATA__ brain0001 lung0001 brain00002 kidney0003 brain00003` [download] Outputs: `[14:52:38.81] C:\test>junk58 { brain => ["0001", "00002", "00003"], kidney => ["0003"], lung => ["0001"], }` [download] But maybe you don't want to load up anything you are not expecting? Maybe you want a warning for lines that don;t match your regex? With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. RIP Neil Armstrong div	[reply] [d/l] [select]
Re^2: populating a HoA with regexp by asqwerty (Novice) on Aug 28, 2012 at 14:07 UTC
Thanks! Actually I want to load only the words I'm expecting, but your answer (and the previous reply) gave me the hint I need	[reply]
Re: populating a HoA with regexp by Athanasius (Vicar) on Aug 28, 2012 at 15:06 UTC
Hello asqwerty, and welcome to the Monastery! You already have the answer you were looking for. I just want to point out that the line: `%dfs = map {$_ => ()} @pref;` [download] is incorrect. You can see this by printing the contents of `%dfs` (using `Data::Dumper`) immediately after that line: `$VAR1 = { 'brain' => 'lung', 'kidney' => undef };` [download] When interpolated into an array or hash, the empty list `()` effectively disappears. I think you meant to write: `%dfs = map {$_ => []} @pref;` [download] which works correctly, although `%dfs = map {$_ => undef} @pref;` [download] also works. Here is some good advice: Get into the habit of including the lines `use strict; use warnings;` [download] at the head of every script. In this case, `warnings` would have shown you the problem: `Odd number of elements in hash assignment at ... line 6.` [download] Hope that helps, Athanasius <°(((>< contra mundum	[reply] [d/l] [select]
Re^2: populating a HoA with regexp by asqwerty (Novice) on Aug 28, 2012 at 15:24 UTC
Thanks a lot! As you point out my code was wrong.	[reply]
Re: populating a HoA with regexp by linuxkid (Sexton) on Aug 28, 2012 at 20:44 UTC
Readability should be valued over brevity/speed --linuxkid imrunningoutofideas.co.cc	[reply]
Re^2: populating a HoA with regexp by Kenosis (Deacon) on Aug 28, 2012 at 21:46 UTC
Quickly said--and with readable brevity! :)	[reply]
Re^2: populating a HoA with regexp by Anonymous Monk on Aug 28, 2012 at 22:04 UTC
Readability should be valued over brevity/speed Learn to speak perl	[reply]
Re^2: populating a HoA with regexp by asqwerty (Novice) on Aug 29, 2012 at 08:05 UTC
I think that `/^($pattern)/ and push @{$dfs{$1}}, $_;` [download] is readable enough. Maybe even more readable (in a perl way) than my previous solution.	[reply] [d/l]

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