Perl advice - Taking in a file and changing contents - perl

Question

I have a request for some advice on how to approach this script I want to write in Perl. Basically I have a file that looks like :
id: 1
Relationship: ""
name: shelby
pet: 1
color:4
There are certain keywords such as pet and color that have numbers after then. I want to be able to take in a file and look for these keywords (there are 5 or 6 of them) and then change the number to the word that number corresponds to. That is to say for the keyword "Pet"---> 0 =dog, 1 = cat, 2=fish. And for the keyword "color" 0 = red, 1=blue,2=purple,3=brown,4=white. The script should find and change these numbers. The goal should be an output file that looks like:
id: 1
Relationship: ""
name: shelby
pet: cat
color:white
I've been struggling with how to do this for a while. I looked up online maybe I could do an array of hashes or something but I'm relatively new to Perl and don't know exactly how to even approach this problem.... Any advice would be much appreciated!
Thanks

Answer 1

If we're talking about a small set of values, you could have a hash of arrays:
%lookups = ( pet => [ "dog", "cat", "fish" ],
color => [ "red", "blue", "purple", "brown", "white" ] );
Then, when you're reading the file, check each keyword against the hash. If it has a key with that keyword in it, replace the value in the line you read with the value from the hash.

Answer 2

Usage: script.pl file.txt > output.txt
use strict;
use warnings;
my %tags = (
"pet" => [ qw(dog cat fish) ],
"color" => [ qw(red blue purple brown white) ],
);
my $rx = join '|', keys %tags;
while (<>) {
s/^\s*($rx):\s*(\d+)/$1: $tags{$1}[$2]/;
print;
}

Answer 3

This should do it
use strict;
my $inputFileName = 'E:\test.txt';
my $outputFileName = 'E:\test2.txt';
my %Colors = ( 1 => 'Red' , 2 => 'Green' , 4 => 'Blue' );
my %Pets = ( 1 => 'Dog' , 2 => 'Cat' );
open( IN , "<" , $inputFileName) or die "$inputFileName could not be opened $!";
open( OUT, ">" , $outputFileName) or die "$outputFileName could not be opened $!";
while(<IN>)
{
my $line = $_;
if (/^(\s*pet\s*:\s*)(\d+)/ )
{
$line = $1. $Pets{$2} . "\n";
}
elsif (/\s*^color\s*:\s*(\d+)/ )
{
$line = $1. $Colors{$2} . "\n";
}
print OUT $line;
}
close(IN);
close(OUT);

Answer 4

Using zigdon's suggestion
#!/usr/bin/perl
use strict;
use warnings;
use 5.014;
my %param = (pet => [qw/dog cat fish/],
color => [qw/ red blue purple brown white/],
);
while (<DATA>) {
if (/^(pet|color):\s*(\d)$/) {
print "$1: $param{ $1 }[$2]\n";
}
else {
print;
}
}
__DATA__
id: 1
Relationship: ""
name: shelby
pet: 1
color:4

Answer 5

If there are not many cases, you can try something like this, to be run with perl -p:
if (/^id/)
{
s/\d+/%h=(1=>"dog",2=>"warf",3=>"ee");$h{$&}/e;
}
if (/^other/)
{
s/\d+/%h=(1=>"other_thing",3=>"etc",4=>"etc2");$h{$&}/e;
}
EDIT:
To automate the tests, you can do something like (also taking the idea of hashes from zigdon):
my #interesting_tags = ("color", "pet");
my $regexp = "(" . join("|" , #interesting_tags) . ")";
my %lookups = ( pet => [ "dog", "cat", "fish" ],
color => [ "red", "blue", "purple", "brown", "white" ] );
while (<>)
{
if (/$regexp/)
{
my $element = $&;
s/\d+/$lookups{$element}[$&]/e;
}
}