RE: array within array

John,

That is exactly what I wanted. Thanks for pointing out all those errors
for me and your help with the script. Appreciate the prompt respond.


Cheers,

Mike

-----Original Message-----
From: John W.Krahn [mailto:krahnj@xxxxxxxxx]
Sent: Monday, October 29, 2007 1:10 PM
To: Perl beginners
Subject: Re: array within array

On Monday 29 October 2007 06:42, Mike Tran wrote:
Hey all,

Hello,

I'm new with Perl and need help with this simple script. I'm still
playing around with the script below to get a feel for Perl. My
script below is incomplete and I'm doing an array within an array
which is incorrect. Please help.

You are not using arrays you are using hashes.

Here's what I want to do; I have to flat files (pipe delimited,
export from a database) that I want to parse through and assign
variables for each column. Basically, I want to parse through
exclude_bases.txt and do: if base_no in exclude_bases.txt equals to
base_no in base.txt then search in the "description" field of
base.txt for the string listed in the "keyword" field in
exclude_bases.tx and replace with "new_keyword" in exclude_bases.txt
and write the out put into a new file called "new_bases.txt".

Any suggestions on how I could accomplish the above task is greatly
appreciated. Thanks all.

Flat Files:

base.txt:
base_no|name|description
10000|test|test desc
10001|test2|test desc 2
10002|test3|test desc 3

exclude_bases.txt:
base_no|keyword|new_keyword|
10000|test desc|testdesc|0
10001|test desc 2|testdesc2|0
10002|test desc 3|testdesc3|1


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

my $exclude_bases = "exclude_bases.txt";
my $current_base = "base.txt";
my $output = "new_bases.txt";

my %exclude_bases;
my $exclude_text;
my $exbase_no;
my $keyword;
my $new_keyword;

You should define variables in the smallest possible scope.


open(EXCLUDE,"exclude_bases.txt" )|| die("Could not open file!");

You have stored the file name in the $exclude_bases variable above so
why do you not use the variable instead? You should include the $!
variable in the error message so you know *why* it failed.


%exclude_bases=<EXCLUDE>;

You are assigning the list from the file to a hash. The list elements
are defined by the value of the $/ variable so here each element of the
list is a line from the file. Because you are assigning to a hash the
first element is a key and the second element is the value for that
key. if any of the keys (odd elements) are the same as a previous key
then the old value will be overwritten by the new value and you will
lose lines from the file.


close(EXCLUDE);

my $base_no ="";
my $name="";
my $description="";
my $current_base="";
my $base_text="";
my %bases;

open(BASE,"base.txt")|| die("Could not open file!");

Same as above.

%bases=<BASE>;

Same as above.

close(BASE);

#choping lines and assign variables to base.txt
foreach $base_text (%bases)
{
chop($base_text);

You should use chomp() instead of chop().


($base_no,$name,$description)=split(/\|/,$base_text);

#choping lines and assign variables to exclude_bases.txt
foreach $exclude_text (%exclude_bases)
{
chop($exclude_text);

Same as above.


($exbase_no,$keyword,$new_keyword)=split(/\|/,$base_text);

if ($exbase_no=$base_no) {

You are assigning the value of $base_no to the variable $exbase_no. If
the value of $base_no is "true" then the expression is "true". You
want to use a comparison operator like '==' or 'eq'.


$keyword =~ s/$keyword/$new_keyword/g;}

Your description said that you wanted to modify 'the "description"
field of base.txt' so that sould be:

$description =~ s/$keyword/$new_keyword/g;}


}
}


It looks like you may want something like this:

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

my $exclude_bases = 'exclude_bases.txt';
my $current_base = 'base.txt';
my $output = 'new_bases.txt';

open EXCLUDE, '<', $exclude_bases or die "Could not open
'$exclude_bases' $!";

my %exclude_bases;
while ( <EXCLUDE> ) {
next if $. == 1; # exclude header
chomp;
my ( $exbase_no, $keyword, $new_keyword ) = split /\|/;
$exclude_bases{ $exbase_no } = { from => qr/\Q$keyword/, to =>
$new_keyword };
}

close EXCLUDE;


open BASE, '<', $current_base or die "Could not open '$current_base'
$!";
open OUT, '>', $output or die "Could not open '$output' $!";

while ( <BASE> ) {
my ( $base_no, $name, $description ) = split /\|/;
if ( exists $exclude_bases{ $base_no } ) {
$description =~
s/$exclude_bases{$base_no}{from}/$exclude_bases{$base_no}{to}/g;
$_ = join '|', $base_no, $name, $description;
}
print OUT;
}

__END__



John
--
use Perl;
program
fulfillment

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