Merging N no of files based on their first column in perl - perl

Question

My question is similar to this question posted earlier.
I am having many files which I need to merge them based on the presence or absence of the first column ID, but while merging I am getting lots of empty values in my output file, I want those empty values to be zero if it is not present in another file. The example below is based on only two files content, but I have many sample files like this format (tabular).
For example:
File1
ID Value
123 1
231 2
323 3
541 7
File2
ID Value
541 6
123 1
312 3
211 4
Expected Output:
ID File1 File2
123 1 1
231 2 0
323 3 0
541 7 6
312 0 3
211 0 4
Obtaining Output:
ID File1 File2
123 1 1
231 2
323 3
541 7 6
312 undef 3
211 undef 4
As you can see above I am getting output but in file2 column, it's not adding zero or leaving empty and in case of file1 column it is having undef value. I have checked undef values and then my final output gives zeros in place of undef values but still I am having those empty spaces. Please find my code below (hardcoded only for two files).
#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;
use Data::Dumper;
my $path = "/home/pranjay/Projects/test";
my #files = ("s1.txt","s2.txt");
my %classic_com;
my $cnt;
my $classic_txt;
my $sample_cnt = 0;
my $classic_txtcomb = "test_classic.txt";
open($classic_txt,">$path/$classic_txtcomb") or die "Couldn't open file
$classic_txtcomb for writing,$!";
print $classic_txt "#ID\t"."file1\tfile2\n";
foreach my $file(#files){
$sample_cnt++;
print "$sample_cnt\n";
open($cnt,"<$path/$file")or die "Couldn't open file $file for reading,$!";
while(<$cnt>){
chomp($_);
my #count = ();
next if($_=~/^ID/);
my #record=();
#record=split(/\t/,$_);
my $scnt = $sample_cnt -1;
if((exists($classic_com{$record[0]})) and ($sample_cnt > 0)){
${$classic_com{$record[0]}}[$scnt]=$record[1];
}else{
$count[$scnt] = "$record[1]";
$classic_com{$record[0]}= [#count];
}
}
}
my %final_txt=();
foreach my $key ( keys %classic_com ) {
#print "$key: ";
my #val = #{ $classic_com{$key} };
my #v;
foreach my $i ( #val ) {
if(not defined($i)){
$i = 0;
push(#v, $i);
}else{
push(#v, $i);
next;
}
}
$final_txt{$key} = [#v];
}
#print Dumper %classic_com;
while(my($key,$value)=each(%final_txt)){
my $val=join("\t", #{$value});
print $classic_txt "$key\t"."#{$value}"."\n";
}

Answer 1

Just read the input files into a hash of arrays. The topmost key is the ID, each inner array contains the value for file i on the i-th position. When printing, use the // defined-or operator to replace undefs with zeroes:
#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };
my %merged;
my $file_tally = 0;
while (my $file = shift) {
open my $in, '<', $file or die "$file: $!";
<$in>; # skip the header
while (<$in>) {
my ($id, $value) = split;
$merged{$id}[$file_tally] = $value;
}
++$file_tally;
}
for my $value (keys %merged) {
my #values = #{ $merged{$value} };
say join "\t", $value, map $_ // 0, #values[0 .. $file_tally - 1];
}

Answer 2

program.pl
my %val;
/ (\d+) \s+ (\d+) /x and $val{$1}{$ARGV} = $2 while <>;
pr( 'ID', my #f = sort keys %{{map%$_,values%val}} );
pr( $_, map$_//0, #{$val{$_}}{#f} ) for sort keys %val;
sub pr{ print join("\t",#_)."\n" }
Run:
perl program.pl s1.txt s2.txt
ID s1.txt s2.txt
123 1 1
211 0 4
231 2 0
312 0 3
323 3 0
541 7 6