Compare two files and retrieve corresponding results

Question

I have two files.File1 contains

470.2843    organism AR_0036     123    Intermediate
470.2845    organism AR_0033    456 Susceptible
903909.3    organism Naval-83   789 Resistant

and file2 contains

123
456
abc
def
789

I want my output such that: if in file2 values do not match with file1, perl leaves those lines blank in the output file; or if it matches, then print the corresponding data of the matched line in the output file.

#!/usr/bin/perl
my $file1 = '/Users/apple/Desktop/ncbi_ab_data/new_file1';
my $file2 = '/Users/apple/Desktop/ncbi_ab_data/new_file2';
open my $fh1, '<' , $file1;
while (<$fh1>){
    chomp;
    my @file1 = split('\t', $_ );

        #print "$file1[0]\t";
        #print "$file1[1]\t";
        #print "$file1[2]\t";
        #print "$file1[3]\t\n";

    open my $fh2, '<' , $file2;
    while (<$fh2>){
    chomp;
    my @file2 = split('\t', $_ );
    #if ($file2[0] == $file1[2])
    #print "$file2[0]\n";
    if ($file2[0] = $file1[2]){
        print "$file2[0]";
        print "\t$file1[3]\n";

    }
    #print "$file1[0]\n";
    #print "$file2[1]\n";
    #print "$file2[2]\n";
    #print "$file2[3]\n";
    #print "$file2[4]\n";
    }
}

I have written this code but it doesn't work properly.

Answer 1

One can use join (for printing and matching field 4 of file1 with field 1 of file2) and sort (for producing ordered input data on field 4 and field 1 of file1 and file2, resp.) to perform the matching:

 join -o 2.1,1.3 -1 4 -2 1 <(sort -k 4 file1) <(sort -k 1 file2)

Using your sample data, it produces

 123 AR_0036
 456 AR_0033
 789 Naval-83

Regarding your script, I guess that index 2 in

 if ($file2[0] = $file1[2]){

is wrong.