How can I merge data using a hash?

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

Hi all, I have 2 files:

FILE 1

complex.1    1.356
complex.2    1.879
etc

file 2
12.02   /home/complex.2out
10.25   /home/complex.1out
etc
[download]

i need to merge the data in file 2 to the relevant rows in file 1 based on the complex number. However, the order in file 2 is not the same as file 1. Thought hash would be useful to lookup the complex numbers. I can merge the data but how can i incorporate the values in file 1 also?

$string = 'complex';

open(REF, "<file1");
chomp;

my %pd_file = map { /^(\S+)\s+(\S+).*/;  } <REF>;

close(REF);

open (ET, "<file2");
while (<ET>) {
   chomp;
/^(\S+\s+\S+)\s+.*($string\.\d+).*$/;
   print OUT  ($1,  $pd_file{$2}) if (exists($pd_file{$2}));
[download]

myoutput is

complex.1  10.25
complex.2  12.02
[download]

Janitored by Arunbear - retitled from 'hash' and balanced code tag around output

Comment on How can I merge data using a hash? Select or Download Code

Replies are listed 'Best First'.
Re: How can I merge data using a hash? by Zed_Lopez (Chaplain) on Oct 10, 2004 at 22:01 UTC
I don't know what to recommend, because I don't know what you mean by merge. If you want to have access to both values, you could use arrayrefs as the values of your hash, and push each value on. Or you could use two different hashes, which might be more sensible depending on what you actually wanted to do with them. What would be the output you'd desire from processing the two files in your example?	[reply]
Re^2: How can I merge data using a hash? by Anonymous Monk on Oct 10, 2004 at 22:07 UTC
the output would look like `complex.1 1.356 10.25 complex.2 1.879 12.02` [download]	[reply] [d/l]
Re: How can I merge data using a hash? (golf it) by ccn (Vicar) on Oct 10, 2004 at 22:40 UTC
`perl -ane '$\|?($F[1]=~/complex.\d/and$a{$&}=$F[0]):($b{$F[0]}=$F[1]);$ +\|\|\|=eof}{print"$_ $b{$_} $a{$_}\n"for keys%b' file1 file2` [download]	[reply] [d/l]
Re: How can I merge data using a hash? by pg (Canon) on Oct 10, 2004 at 21:57 UTC
As for data structure, how about hash of array ref. The hash key is your complex number. Each array ref contains two numbers, one from file1, and one from file2.	[reply]
Re^2: How can I merge data using a hash? by Anonymous Monk on Oct 10, 2004 at 22:13 UTC
never used references to an array, any advice?	[reply]
Re^3: How can I merge data using a hash? by pg (Canon) on Oct 10, 2004 at 22:15 UTC
Some code: (you may have to refine a bit, do things like output formating, sorting etc.) `use Data::Dumper; use strict; use warnings; my $hash; open(FILE, "<", "file1.txt"); while (<FILE>) { my ($k, $v) = split " "; $hash->{$k}->[0] = $v; } close FILE; open(FILE, "<", "file2.txt"); while (<FILE>) { my ($v, $k) = split " "; $k = /(complex\.\d+)/; $hash->{$1}->[1] = $v; } close FILE; print Dumper($hash); open (OUT, ">", "out.txt"); for my $key (keys(%$hash)) { print OUT $key . " " . $hash->{$key}->[0] . " " . $hash->{$key}->[ +1] . "\n"; } close OUT;` [download]	[reply] [d/l]
Re^3: How can I merge data using a hash? by Roy Johnson (Monsignor) on Oct 11, 2004 at 15:41 UTC
`perldoc perlreftut` Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re: How can I merge data using a hash? by TedPride (Priest) on Oct 10, 2004 at 22:38 UTC
I'm assuming every line contains data and that the files are in tab delimited format. `use strict; my @file1 = ( "complex.1\t1.356\n", "complex.2\t1.879\n", ); my @file2 = ( "12.02\t/home/complex.2out\n", "10.25\t/home/complex.1out\n", ); my (%hash, $ref, $values); chomp(@file1); chomp(@file2); foreach (@file1) { $_ =~ /^complex\.(\d+)\t([\d\.]+)$/; $hash{$1}->[0] = $2; } foreach (@file2) { $_ =~ /^([\d\.]+)\t\/home\/complex.(\d+)out$/; $hash{$2}->[1] = $1; } foreach (sort {$a <=> $b} keys %hash) { $ref = $hash{$_}; $values = join("\t", @$ref); print "complex.$_\t$values\n"; }` [download]	[reply] [d/l]
Re^2: How can I merge data using a hash? by Anonymous Monk on Oct 10, 2004 at 23:00 UTC
could you explain this: `$hash{$1}->[0] = $2` [download] is it a reference to an array? so the key is $1...	[reply] [d/l]
Re^3: How can I merge data using a hash? by TedPride (Priest) on Oct 10, 2004 at 23:35 UTC
Yes, it's a reference to an array. For instance: `$hash{$1}->[0] = $2; $ref = $hash{$1}; print @$ref[0];` [download] $ref points to the array. @$ref is the array that $ref points to.	[reply] [d/l]