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Consider this:
#!/usr/bin/perl -w use strict; my $FILE1 = <<END; ID1 50 ID2 60 ID3 100 END my $FILE2 = <<END; ID1 20 ID2 100 ID3 10 END my %ids; foreach my $file (\$FILE1, \$FILE2) #just put path name of #FILE1 and FILE2 here. #This ref is special because of #putting the file contents within #the code. #FILE1 and 2 are "hereis" docs. { open (FILE, "<", $file) or die "unable to open $file for read $!"; while (<FILE>) { chomp; # delete trailing \n # here I split on one or more space characters, # A tab char doesn't show up well on this forum's text my ($id, $value) = split (/\s+/, $_); push @{$ids{$id}}, $value; } } #Each key of the hash of %ids contains a reference to #an array of id's. This is called a HoA - Hash of Array foreach my $id (sort keys %ids) { print "$id @{$ids{$id}}\n"; } #This code will run very fast because each line is #only read one time - Input/Output (I/O) is very #"expensive" __END__ OUTPUT: ID1 50 20 ID2 60 100 ID3 100 10

In reply to Re^3: Join files using perl by Marshall
in thread Join files using perl by linseyr

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