Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I want to create a matrix with different numerical values and save it to a .txt file. also I want to read this matrix values from the file and perform operations on it and save it again, any idea? Thanks...

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Re: Create matrix and save to a file
by varian (Chaplain) on Apr 19, 2007 at 08:00 UTC
    A convenient method I use to save an arbitrary structure of data to a textfile is to use our famous Data::Dumper core module to capture the variable's content in a string.
    When I need it again I just use an eval to convert the string back into my matrix or other datastructure. 
    #!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my @data = (0,1,2,3 );
print "BEFORE: ",join(',',@data),"\n";
my $saved_data = Dumper(\@data);
# ...here you would write saved data to textfile
my $VAR1; eval $saved_data;
my @data2 = @{$VAR1};
print "AFTER: ",join(',',@data2),"\n";

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    Output would be: 
    BEFORE: 0,1,2,3
AFTER: 0,1,2,3

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Re: Create matrix and save to a file
by stonecolddevin (Parson) on Apr 19, 2007 at 06:26 UTC

    Not sure if these are what you're looking for, but a few of the Bio:: namespace modules looked good. Link: Matrix.

    meh.
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Re: Create matrix and save to a file
by agianni (Hermit) on Apr 19, 2007 at 11:39 UTC

    If your specific mention of a text file was arbitrary, you might consider Storable, which easily and efficiently stores a data structure for reuse at a later time. The downside is that the file isn't human readable. 

    perl -e 'split//,q{john hurl, pest caretaker}and(map{print @_[$_]}(joi
+n(q{},map{sprintf(qq{%010u},$_)}(2**2*307*4993,5*101*641*5261,7*59*79
+*36997,13*17*71*45131,3**2*67*89*167*181))=~/\d{2}/g));'

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Re: Create matrix and save to a file
by fmerges (Chaplain) on Apr 19, 2007 at 07:54 UTC

    Hi,

    Hi, you can do that with any serialization module. For example you can use YAML::Syck.

    BTW there's also PDL

    Regards,

    fmerges at irc.freenode.net
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Re: Create matrix and save to a file
by logie17 (Friar) on Apr 19, 2007 at 15:42 UTC
    First I would check out some tutorials on Input and Output. Once you understand basic filehandles and how to read/create files then manipulating the data is fairly straightforward.
    s;;5776?12321=10609$d=9409:12100$xx;;s;(\d*);push @_,$1;eg;map{print chr(sqrt($_))."\n"} @_;
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Re: Create matrix and save to a file
by Moron (Curate) on Apr 19, 2007 at 16:31 UTC
    It's trivial enough to just code this. See perlref, for, open, split, join, print, close. The operator for reading from a file is to enclose the filehandle in '<' '>'. A matrix in Perl is just an array of array references, e.g. 
    # matrix of random numbers
my @matrix;
for my $y ( 0..9 ) {
    my @row = ();
    for my $x ( 0..9 ) {
        push @row, 100*rand();
    }
    push @matrix, \@row;
}

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    ^M Free your mind!

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