Chart::EPS_graph.pm
Version 0.02
my $eps = Chart::EPS_graph->new(600, 600);
$eps->set(
label_top => 'Graph Main Title',
label_y1 => 'Y1 Axis Measure (Units)',
label_y2 => 'Y2 Axis Measure (Units)',
label_x => 'X Axis Measure (Units)',
);
$eps-set(
names => \@all_13_name_strings,
data => \@all_13_data_arefs,
y1 => [7, 8, 10, 11],
y2 => [9, 12],
);
$eps->set(
label_y1_2 => 'Extra Y1 Axis Info',
label_y2_2 => 'Extra Y2 Axis Info',
label_x_2 => 'Extra X Axis Info',
#
# Any common browser color no matter how hideous.
bg_color => 'DarkOliveGreen',
fg_color => 'HotPink',
web_colors => ['Crimson', 'Lime', 'Indigo', 'Gold', 'Snow', 'Aqua'],
#
# Any known I<PostScript> font no matter how illegible
font_name => 'ZapfChancery-MediumItalic',
font_size => 18,
#
# See POD about this one. But in brief:
# If set to "1" channel innumeration gaps will be closed.
# If set to "0" (the default) they will be left as they are.
close_gap => 0,
#
# If the 0th channel is not for the X axis (the default) then the
# data point count is used as the X axis, which you may scale.
# So if X were Time in seconds, with no 0th channel having acutally
# recorded it, but each data point were known to be 0.5 seconds...
$self->{x_is_zeroth} = 0; # Boolean, so '1' or '0'.
$self->{x_scale} = 0.5; # Have 10th datapoint show as 20, etc.
);
$eps->write_eps( cwd() . '/whatever.eps' ); # Write to a file.
$eps->display(); # Display in viewer (autodetects 'gv' or 'gsview.exe').
$eps->display('GS'); # Convert to PNG via Ghostscript.
$eps->display('GIMP'); # Open for editng in The GIMP.
Creates line graphs in PostScript as *.eps format. Coversion to *.png
or other formats via Ghostscript may be accomplished using either gv on
Unix or GSView.exe on Win32.
You may have two Y axes, one each to left and right. The PostScript code will auto-reconcile a grid for optimum alignment between both of these Y axes. By optimum I mean that scales will be adjusted such that curves traverse the entirety of available Y-axis space.
You may use as many of the named colors from the W3C table at
http://www.w3schools.com/html/html_colornames.asp as you like in any order
that you like.
Asked to display an EPS graph, a 3rd party viewer (gv on UNIX, gsview.exe
on Win32), coverter Ghostscript or editor The GIMP will be called up to
display, convert or edit the EPS graph.
These you may either close or leave open. For example, suppose you have ten channels total but only wish to graph five of them. And suppose those channels are staggerd thus: 1, 3, 5, 6, 9. Closing the innumeration gap would make those channels appear on the graph as if they were numbered 1, 2, 3, 4, 5. They would also display in the first five colors, those which are most appealing and afford the best contrast.
Closing the innumeration gap makes a stand-alone graph easier to read. Should you, however, have more than one graph, with different channel sets on each, then it is a bad idea. Better in such a case that each color be true to a channel than easier upon the eye.
Closing the gap will also reduce file size considerably, as detailed next.
Data arrays for all channels, even those not to be shown, will be embeded into the PostScript output file. Traces which are shown will display their true channel numbers and be colorized in accordance with that true number.
Say, for instance, you are only showing Channel 12. It will be labeled as trace number 12 and display in the 12th color. This makes a lot of sense when you have a dozen graphs layed out on a table for none-too-bright customers to argue over.
Why do this? The PostScript program was originally written to run stand- alone. This feature makes it easy to have one file and, with a minor hand edit, generate any number of subsets for all all possible graphs by simply editing the /not_shown array. It also allows for the same channel to always display in a given number and color no matter if any other channels are not being shown.
Data arrays for only those channels assigned to a Y axis will be embeded into the PostScript output file. Traces which are shown will display new channel numbers (1 thru N) without any gaps and be colorized in accordance with that new number.
A separate test module exists to fully test this one. See POD at head of that module for full details. But in short, you may call the full test on a single line, or broken over two, as below...
perl -e "use Chart::EPS_graph::Test; \
print Chart::EPS_graph::Test-E<gt>full_test('/some/dir');"
...and thereby obtain a multi-step report as below...
Testing Chart::EPS_graph.pm in path '/some/dir/'
Okay! File 'foo.eps' has expected first two lines.
Okay! File 'foo.eps' looks fresh: 0 seconds old.
Okay! File 'foo.eps' looks big enough, 28319 bytes.
Okay! Ghostscript created 'foo.eps.png'.
Okay! File 'foo.eps.png' looks fresh: 1 seconds old.
Okay! File 'foo.eps.png' looks big enough, 105828 bytes.
Glad Tidings! All tests okay for Chart::EPS_graph.
Had there been a problem of any kind, one or more of the above lines would have
begun as Oops! ... followed by a few terse details. You can also inspect the
example files personally via The GIMP or ImageMagick as you choose.
This module requires no configuration. It auto-searches for its dependencies
by calling to File::Find.
My goal, as always, is OS-independence, but only have recources to design and test on these two platforms only:
Because output is to PostScript (which is not easily made use of in anything
but print-to-paper output) most users will want to convert the output to some
other graphics format. For *.png on UNIX platforms a built-in method is
provided.
For other formats, such JPEG, you will require an interpreter program. The best one is GhostScript but it can often be a hassle to deal with. For this reason other 3-rd party viewer programs exist which take all those hassles away.
The Ghostscript interpreter for PostScript files is free and available
for all platforms. This is what will make sense of your *.eps files and
convert them for viewing on screen. But since it is command-line only (no GUI)
most folks talk to it only through GUI-enabled viewer programs. So what you do
is just install Ghostscript and then pretty much forget it is there, letting
the viewer (described next) interface with Ghostscript for you.
These too are free. Unlike Ghostscript, there are several, depending on your particular platform. Being GUI-enabled, they are much more user-friendly than is Ghostscript itself. What they do is talk to Ghostscript in the background, hiding its complexity and thus making Ghostscript easy to use.
Whatever your platform, one of these viewers will be available from the same place as you will have gotten Ghostscript itself.
The program GSView.exe will display *.eps files and also convert them to
to other formats. Conversion from *.eps to *.png is excellent.
The program gv will display *.eps files and also convert them to other
formats. Display on-screen is excellent. But conversion from *.eps to
*.png, etc, seems to come out only so-so. Probably the fault is mine in that
I've not yet sufficiently nuanced its configuration for these conversions to
match its display. But that is no matter as The GIMP (see next item) performs
this function very well. Or better yet, built-in conversion to *.png is
built in for Unix (see Synopsis above).
The Gnu Image Management Program (aka The GIMP) is a full-bodied graphic
image editor which, among its many other features, can also read in *.eps
files via Ghostscript. And any format it can read it, it can also convert and
write out. And did I mention...The GIMP is both free and open-source.
When you open an *.eps file in The GIMP it will pop up a menu for how you
want the *.eps file to be read in. Select the "Try Bounding Box" checkbox.
Then note the two antialiasing radio buttons. Select "weak" for text and
"strong" for graphics. This will make bring up an image which looks just like
the default, on-screen display which gv and GSView (see items above)
provide.
None known as yet.
Owing to inbuilt addressing limitations of PostScript, data sets may not exceed 65,535 data points.
This program, being free software, carries absolutely no warranties or guarantees of any kind, neither expressed, implied, or even vaguely hinted at.
The PostScript definitions herein embeded derive from a standalone
PostScript program named OmniGraph.ps which I wrote sometime circa 1992.
This I did in response to frustrations over an upgrade by Measurments Group to
the software in their System 5000 strain gage instrument versus the graphing
feature in their older System 4000.
I'd already gotten kind of handy in PostScript from wrangling with the PostScript prolog files of Amiga 2000 programs like Excellence! and Gold Disk so as to publish in Esperanto for which I could find no fonts. But that I was able to deal with on my own in due course, and for several platforms besides my own beloved Amiga.
As an aside I cannot refrain from relating that this particular frustration also proved to be the font (pun intended) of my initial anger and dismay at Microsoft. Since once I had learnt how to solve this dilemma for both the Amiga and for the Macintosh I next turned (as a community service) to do so for MS Word and I found it imposible. How so? Entirly because Mr. Gates had done two things to thwart me: First he'd encrypted MS Word's PostScript prolog file for no good reason. And second, once I had managed to decrypt said prolog, I next found the fiend to have therin called the PostScript 'exitserver' command entirely contrary to warnings forbidding such in the official PostScript docs. My Microsoft-ish experiences since have only deepened that sentiment further. But I digress...
From there I went kind of wild with PostScript, using it in all manner of ways for which it was probably not intended. This I could in no wise have done without the continuing example of Don Lancaster, noted PostScript guru, for his many excellent articles in Publish magazine and elsewhere.
Most of those ancient efforts have now lain fallow many a year. But once again,
this time in frustration over a (for most folks, trifling) lack in the Perl
module GD::Graph::lines, I have resurrected my old, trusty OmniGraph.ps
and grafted it piecemeal, with some changes, into this new module
Chart::EPS_graph.pm so as to work around that specific issue where
GD::Graph::lines chokes on dual Y axes needing multiple channels.
Gan Uesli Starling <gan@starling.us>
This program is free software; you may redistribute and/or modify it under the same terms as Perl itself.
Copyright (c) 2006 Gan Uesli Starling. All rights reserved.