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Re: comparing two lists

by scottstef (Curate)
on Jun 24, 2001 at 19:21 UTC ( #91069=note: print w/ replies, xml ) Need Help??


in reply to comparing two lists

I recently did something similar comparing items that were in two different files using hashes. Each hash had a primary key that was the list name with a value of 1 if it exixted in the first file, 2 if it existed in both files, and 3 if it was only in the secoond file.

my $file1 = "/home/scott/file1"; my $file2 = "/home/scott/file2"; my $hashOfLists; my %hashOfLists; open (FILE1, "$file1") or die "Could not open $file1 $!"; open (FILE2, "$file2") or die "Could not open $file2 $!"; ###################################################### #####This block reads all of the items of the file into #####a hash with the item being the key. Since I ##### was comparing 2 files each key received a #####value of 1 if it was in the first file, 2 if #####it was in both , and 3 if it was only in file 2 ###################################################### foreach (<FILE1>) { chomp $_; $hashOfLists{$_} =1; } foreach (<FILE2>) { chomp $_; ###################################################### #####if exists checks the hash to see if $_ exists. ##### If true $_'s value becomes 2, #####if false, $_ gets a value of three ###################################################### if (exists $hashOfLists{$_}) { ($hashOfLists{$_}) =2; } else { ($hashOfLists{$_})=3; } } close FILE1 or die "Could not close $file1 $!"; close FILE2 or die "Could not close $file2 $!";

"The social dynamics of the net are a direct consequence of the fact that nobody has yet developed a Remote Strangulation Protocol." -- Larry Wall


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