if the index is just a running number just use only one array  $dict[$column1] = $column2.
BTW replacement becomes easy (by checking with exists/defined $dict[$number] and then replace).
UPDATE:
I just misunderstood the question, pardon me.
It is solvable using hash itself.

---

Vivek
-- In accordance with the prarabdha of each, the One whose function it is to ordain makes each to act. What will not happen will never happen, whatever effort one may put forth. And what will happen will not fail to happen, however much one may seek to prevent it. This is certain. The part of wisdom therefore is to stay quiet.

This wouldn't work as well because he needs to find the words in his string, and use the numbers to replace them. That is, the index should be the data from the input file, which is words, not numbers. Using the numbers as the index would force him to search the entire list for each word which needs to be replaced (although it would save him one array compared with his current two array approach). Using the words themselves as hash keys allows him to do a simple lookup.

Don't know if my approach is any better, but I had the same issue many years ago. Had a tab-delimited file that needed to be search and replaced for multiple terms in multiple columns. Instead of running a search and replace in Excel over and over for each item, I wrote a Perl script to read a mapping file (search term \t replace term) and do a "single pass" global search and replce

I've updated over the years to not just do columns. You may find it useful. It's in the Code area:

UPDATE:

{C} > more in.txt
the dog chased my cat.

{C} > more mapping.txt
dog     1
cat     2
chased  3
the     4

{C} > msar in.txt mapping.txt
Reading mappings from file:  mapping.txt
----------------------------
4 1 3 my 2.
----------------------------
Mapped 4 entries.

{C} >
[download]

I found a problem in your codes. While I have a text as below:

april
barrel
[download]

and a dictionary like this:

225    April
1168    barrel
3143    Il
9432    PR
....
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I get this as output form my input

a94323143
11777rr340
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I dont know why april would be broken to a + PR + Il ...

It happens because the map file is read into a hash and normally there is no "order" to a hash. Thus, you can't guarantee that the search and replace will happen in the order you give in you map file.

You're actually hitting this part of the code:

        # user didn't specify columns, so just SAR each line and leave
+ alone
        } else {

            # loop through mapping array for each line
            foreach my $replace (keys(%map)) {
                # ignore case?
                if (defined($opt_ignore)) {
                    $YESMapping += ($_ =~ s/$replace/$map{$replace}/gi
+)
                } else {
                    $YESMapping += ($_ =~ s/$replace/$map{$replace}/g)
                }
            }
            print $OUT $_
        }
[download]

Stick in a helpful print to "debug" what's going on:

        # user didn't specify columns, so just SAR each line and leave
+ alone
        } else {

            # loop through mapping array for each line
            foreach my $replace (keys(%map)) {
                # ignore case?
                if (defined($opt_ignore)) {

print "SAR on $_ with $replace\n";

                    $YESMapping += ($_ =~ s/$replace/$map{$replace}/gi
+)
                } else {
                    $YESMapping += ($_ =~ s/$replace/$map{$replace}/g)
                }
            }
            print $OUT $_
        }
[download]

This is what we see using your input and mapping files:

{C} > msar input.txt map.txt -r -i
Reading mappings from file:  map.txt
----------------------------
SAR on april
 with il
SAR on apr3143
 with barrel
SAR on apr3143
 with april
SAR on apr3143
 with pr
a94323143
SAR on barrel
 with il
SAR on barrel
 with barrel
SAR on 1168
 with april
SAR on 1168
 with pr
1168
----------------------------
Mapped 3 entries.
[download]

You could maybe fix it by adding in Tie::Hash (I think) which is supposed to be able to order your hash. You would need to manipulate the hash variable %map when it is loaded at the beginning of the program. Unfortunately, I don't have the time now to code this up, but hey, my Perl code is "open source" :-) so have at it!

UPDATE: If your infile is just the one column of words, call with:

{C} > msar input.txt map.txt -r -i -c 1

{C} > msar.pl in.txt map.txt -i -r -c 1
Reading mappings from file:  map.txt
----------------------------
225
1168
----------------------------
Mapped 2 entries.
[download]

UPDATE: MSAR.pl code now updated to use -w option which replaces on WHOLE WORDS only. Also, map.txt file will be read AND parsed AND used in search and replace in the order it is written (line 1, line 2 ... line n).

Thanks ... nice work :)

I just realized that I have your "mapping file" backwards, so I added a "-r" (reverse) option so you can keep your mapping file the way you have it and still use the program. I just uploaded the new code about 5 mins ago (called version 1.31 dated 17 MAR 2009) so check that out if you haven't already.

#!/usr/bin/perl

use strict;

my $old_string = "the dog chased my cat.";
my ($new_string, $found_word);
my %dict;

while( <DATA> ) {
    my ($key, $val) = $_ =~ /^(\d)\s(\w+)/;
    $dict{$val} = $key;
}

chop( $old_string );
my @words = split( " ", $old_string);

foreach my $i ( @words ) {
    foreach my $j ( keys %dict ) {
        if ( $j eq $i ) {
            $new_string = $new_string . "$dict{$j} ";
            $found_word++;
        }
    }
    $new_string = $new_string . "$i " if ($found_word == 0);
    $found_word = 0;
}

chop( $new_string );
print "$new_string.";

__DATA__
1 dog
2 cat
3 chased
4 the
[download]

How about like this:

#!/usr/bin/perl
use warnings;
use strict;

my $old_string = 'the dog chased my cat.';

my %dict;
while ( <DATA> ) {
    my ( $key, $val ) = /^(\d+)\s+(\w+)/;
    $dict{ $val } = $key;
    }

my $cc = join '', keys %dict;
my ( $min ) = my ( $max ) = map length, keys %dict;
for ( map length, keys %dict ) {
    $min = $_ if $min > $_;
    $max = $_ if $max < $_;
    }

my $pattern = qr/\b([$cc]{$min,$max})\b/;

( my $new_string = $old_string ) =~ s/$pattern/ exists $dict{ $1 } ? $
+dict{ $1 } : $1 /eg;

print "$old_string\n$new_string\n";


__DATA__
1 dog
2 cat
3 chased
4 the
[download]

I defined it like this:

#!/usr/bin/perl
use warnings;
use strict;

open (DATA, "dic") || die "Error opening the input file\n"; 
print "Reading mapping file\n";
print "----------------------------\n";
    
open (INFILE, "trial.txt") || die "Error opening the input file\n"; 
print "Reading input file\n";
print "----------------------------\n";

my %dict;

while (my $line = <INFILE>) {
my $old_string = $line;
while ( <DATA> ) {
    my ( $key, $val ) = /^(\d+)\s+(\w+)/;
    $dict{ $val } = $key;
    }

my $cc = join '', keys %dict;
my ( $min ) = my ( $max ) = map length, keys %dict;
for ( map length, keys %dict ) {
    $min = $_ if $min > $_;
    $max = $_ if $max < $_;
    }

my $pattern = qr/\b([$cc]{$min,$max})\b/;

( my $new_string = $old_string ) =~ s/$pattern/ exists $dict{ $1 } ? $
+dict{ $1 } : $1 /eg;
print "$new_string\n";

}
close (INFILE);
close (DATA);
[download]

but I get this error:

Reading mapping file
----------------------------
Reading input file
----------------------------
april 1168 0.06781456

Use of uninitialized value in concatenation (.) or string at seek.pl l
+ine 29, <DATA> line 19969.
Use of uninitialized value in concatenation (.) or string at seek.pl l
+ine 29, <DATA> line 19969.
Unmatched [ in regex; marked by <-- HERE in m/\b([ <-- HERE ]{,})\b/ a
+t seek.pl line 29, <DATA> line 19969.
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Not that 19969 is my last line in dictionary file. and also how can I ignore the cases in matching? for example in dictionary file April exists but april does not, so I tend to make it case insensetive. thanks in advance.