How can I use Perl, how can I create charts using values in a CSV file?
I am new to this and need a hint on how to do this. I have a csv file with the following example data:
site,type,2009-01-01,2009-01-02,....
X,A,12,10,...
X,B,10,23,...
Y,A,20,33,...
Y,B,3,12,...
and so on....
I want to create a perl script to read data from a csv file (as per user given) and generate XY (scatter) charts. Let's say I want to create a chart for date 2009-01-01 and type B. The user must enter something like "2009-01-01 B" and the chart should be created with values from a CSV file.
Can anyone suggest me some code to start with?
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I need to do some scatter plots and have been playing around with the module suggested in other answers. In my opinion, the data obtained with GD :: Graph :: Cartesian is too large and the module does not provide any methods to manipulate this parameter, so I hacked my copy Cartesian.pm
(search iconsize
if you want to do the same).
use strict;
use warnings;
use Text::CSV;
use GD::Graph::Cartesian;
# Parse CSV file and convert the data for the
# requested $type and $date into a list of [X,Y] pairs.
my ($csv_file, $type, $date) = @ARGV;
my @xy_points;
my %i = ( X => -1, Y => -1 );
open(my $csv_fh, '<', $csv_file) or die $!;
my $parser = Text::CSV->new();
$parser->column_names( $parser->getline($csv_fh) );
while ( defined( my $hr = $parser->getline_hr($csv_fh) ) ){
next unless $hr->{type} eq $type;
my $xy = $hr->{site};
$xy_points[++ $i{$xy}][$xy eq 'X' ? 0 : 1] = $hr->{$date};
}
# Make a graph.
my $graph = GD::Graph::Cartesian->new(
width => 400, # Image size (in pixels, not X-Y coordinates).
height => 400,
borderx => 20, # Margins (also pixels).
bordery => 20,
strings => [[ 20, 50, 'Graph title' ]],
lines => [
[ 0,0, 50,0 ], # Draw an X axis.
[ 0,0, 0,50], # Draw a Y axis.
],
points => \@xy_points, # The data.
);
open(my $png_file, '>', 'some_data.png') or die $!;
binmode $png_file;
print $png_file $graph->draw;
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OK, for entertainment purposes only:
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
use List::AllUtils qw( each_array );
my $dbh = DBI->connect("DBI:CSV:f_dir=.", undef, undef, {
RaiseError => 1, AutoCommit => 1,
}
);
my $sth = $dbh->prepare(qq{
SELECT d20090101 FROM test.csv WHERE type = ? and site = ?
});
$sth->execute('B', 'X');
my @x = map { $_->[0] } @{ $sth->fetchall_arrayref };
$sth->execute('B', 'Y');
my @y = map { $_->[0] } @{ $sth->fetchall_arrayref };
my @xy;
my $ea = each_array(@x, @y);
while ( my @vals = $ea->() ) {
push @xy, \@vals;
}
my @canvas;
push @canvas, [ '|', (' ') x 40 ] for 1 .. 40;
push @canvas, [ '+', ('-') x 40 ];
for my $coord ( @xy ) {
warn "coords=@$coord\n";
my ($x, $y) = @$coord;
$canvas[40 - $y]->[$x + 1] = '*';
}
print join "\n", map { join '', @$_ } @canvas;
Adding axes and improving on ScatterPlot - a really frustrating module - is left as an exercise for the reader.
Please note that I always need to cheat when it comes to SQL. I would appreciate a correct JOIN
one that eliminates the need for @x
, @y
and each_array
.
Output:
| | | | * | | | | | | | | | | | | | | | | | * | | + ----------------------------------------
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