Mastering Perl for Bioinformatics [Electronic resources] نسخه متنی

Chapter 8. Perl and Graphics

The
importance of an attractive and useful graphical display of
information is fundamental to scientific programming. Just imagine
the difference between seeing a graph of this week's
stock market activity, and seeing a list of several pages of numbers
describing the same activity. The former can be surveyed in a glance;
the latter requires considerable study. The same principle applies to
the display of results in bioinformatics. Of course, sometimes you
need the raw data; but very often what you need is the overview that
a good graphic can provide.

Although there are many programming systems to produce graphics, the
most popular are those that can be displayed via web browsers. This
chapter builds on what you learned in Chapter 7 by
showing you how to add graphics to your display of scientific results
on a web page.

My vehicle of choice for displaying scientific data is the
GD.pm
module, which allows you to produce images in the standard graphics
formats PNG (Portable Network Graphics) and
JPEG (Joint Pictures Expert Group), among
others. I'll also briefly mention the graphics
packages ImageMagick and Gimp, two more full-featured graphics
creation and manipulation packages.

GD.pm is an interface to the
gd graphics library written in the C
programming language by Thomas Boutell. The gd graphics library
is fairly basic; it's fast, it handles text and
various kinds of lines and space filling by means of its various
functions, and it is easy to program elements such as graphs.

The main reason for its success, however, based on those important
technical reasons, is that it makes it possible to produce
nice-looking graphics from your web site on-the-fly, in immediate
response to a request from a user submitting a form.