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making presence/absence table from a hash of arrays

by reubs85 (Acolyte)
on Sep 05, 2011 at 18:21 UTC ( #924283=perlquestion: print w/ replies, xml ) Need Help??
reubs85 has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

Please impart some Perl wisdom to a poor and pitiful Monkling...

Allow me to paint a simplistic picture of my conundrum: I have an array with (for arguments sake) 5 elements, thus:

one two three four five

And I have a hash where the keys are row numbers and the values are references to an array; this array having a varying number of elements that are equal to the headers in the table, but not necessarily in the same order, like so:

row_1 = one five two row_2 = four two row_3 = three one five four etc...

What I would dearly like is to print a table where each cell is filled with a 1/0 presence/absence binary, depending on if the column header in question is present in the array, thus for the hypothetical example above, we would get:

one two three four five row_1 = 1 1 0 0 1 row_2 = 0 1 0 1 0 row_3 = 1 0 1 1 1 etc...

Any tips or pointers would be massively appreciated,

Thanks very much!

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Re: making presence/absence table from a hash of arrays
by Anonymous Monk on Sep 05, 2011 at 18:33 UTC

      Thanks for the responses everyone,

      Incidentally, it is not 'homework'; I am a PhD genome biologist still getting to grips with the finer details of Perl - I am going to use the code as part of a script that will allow me to count genes which are shared across different species. The example I wrote was merely for ease of readership.

      So whilst its true that I should learn more about the grep and map functions (although asking questions is part of learning, I think), I'm not skipping my way through some homework assignment.

      Thanks again!

        It is certainly possible to get a lot done without fancy map statements. There is certainly something to be said for doing something straightforward with foreach loops. Don't worry about being compact/terse - do something that is easy for you to understand - worry about more complex constructs when you are writing a lot more Perl.

        See code below. Perl is great at translating one thing into another thing - the hash table. So I just make a hash table table to translate the column name into an array index. This also perhaps could have been just statically declared, but I wanted to make this flexible. For each row in the table, I just zero out an array and use the name2Index translator to turn on the appropriate elements and then print that row.

        #!/usr/bin/perl -w use strict; use Data::Dump qw(pp); my $header_row= 'one two three four five'; my %table = ( row_1 => [qw(one five two)], row_2 => [qw(four two)], row_3 => [qw(three one five four)], ); my %name2Index; my $col=0; foreach my $col_head (split ' ',$header_row) { $name2Index{$col_head} = $col++; } print "name2Index table = ",pp(\%name2Index),"\n\n"; foreach my $row (sort keys %table) { my @bitmap = (0) x keys %name2Index; foreach my $col_name (@{$table{$row}}) { $bitmap[$name2Index{$col_name}] = 1; } print "$row = @bitmap\n"; } __END__ name2Index table = { five => 4, four => 3, one => 0, three => 2, two = +> 1 } row_1 = 1 1 0 0 1 row_2 = 0 1 0 1 0 row_3 = 1 0 1 1 1
Re: making presence/absence table from a hash of arrays
by jwkrahn (Monsignor) on Sep 05, 2011 at 19:58 UTC
    $ perl -le' my @array = qw/ one two three four five /; my %hash = ( row_1 => [ qw/ one five two / ], row_2 => [ qw/ four two / ], row_3 => [ qw/ three one five four / ], ); print "@array"; for my $key ( sort keys %hash ) { print "$key = ", join " ", map { my $elem = $_; grep( $_ eq $elem, + @{ $hash{ $key } } ) ? 1 : 0 } @array; } ' one two three four five row_1 = 1 1 0 0 1 row_2 = 0 1 0 1 0 row_3 = 1 0 1 1 1

      The grep can be simplified with a smart match:

      for my $key (sort keys %hash) { say "$key = ", join ' ', map $_ ~~ $hash{$key} ? 1 : 0, @array; }
Re: making presence/absence table from a hash of arrays
by Anonymous Monk on Sep 06, 2011 at 09:39 UTC

    You clearly want to use a regular expression:

    #!/ichigo/perl use v5.12; use warnings; use strict; my @array = qw/ one two three four five /; my %hash = ( row_1 => [ qw/ one five two / ], row_2 => [ qw/ four two / ], row_3 => [ qw/ three one five four / ], ); my $row = "@array"; say $row; for my $key (sort keys %hash) { my $re = join '|', @{$hash{$key}}; say "$key = ", grep s/\b($re)\b|\w+/$#-/g, "$row"; }

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