Preview is a graph plotting utility for visualising two dimensional serial numerical data

Preview is a graph plotting utility for visualising two dimensional serial numerical data.

Keywords: Graphics, line, chart, graph, plot, raw data, Linux, Open Source, time series

Copyright: Swerdna's Open Source Software: GNU General Public License (GPL).

Status: this software has full stable release status. This software cannot be depended on in important applications. Important applications require warranted, commercially guaranteed software. Preview of course carries no warranty of any kind including expressed or implied warranties and you use it entirely at your own risk.

Download the files: The executable package is located at sourceforge: download package preview_r.1.0.tar.gz. That contains an executable called preview, a test data file called infile.dat and an information page called readme.html. The source code is downloadable on this site.

Installation: Simply place the executable in your machine's path. You can determine the path on your machine with this shell command: echo $PATH, like so:

username@opensuse:~> echo $PATH
/opt/kde3/bin:/home/username/bin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11
username@opensuse:~>

You can put preview in any of the directories included in your path but conventionally you would put it in /usr/local/bin to make it availabe to all users on the system. I recommend that approach but if you really want a local "bin" directory like /home/charlie/bin and you don't have one, you can create the directory and add it to your local path by editing your local .bashrc file and adding this line:

export PATH=$PATH:/home/your_username/bin

Data Files: The data are two dimensional and are contained in a text file as two columns of spatial X,Y or temporal T,Y values in any of the modern numerical formats. The data can be separated by space/s or a comma.

Options: You'd need to understand a little about code to follow these options: I've dimensioned for 10000 X,Y points but you can change that in the source code and recompile as outlined in my page about FreeBasic. You can also change the display size and resolution by recompiling after swapping the "screen" statements I've included as comments in the code.

Command Line: You can produce a chart from a datafile called e.g. datafile with this shell command:

preview /path_to/datafile

If you invoke the application with the expression preview without including a filename for the data, the programme will look for a default file named infile.dat in the same directory; i.e. infile.dat is a default data file in the absence of specifying one.

Help File: You can display the help file by pressing key h when the application is running. The help file describes navigation, zooming and scrolling by using mouse clicks and keys. Here's the help file:

Move the chart: up, down, right, left = ↑ ↓ → ←

Move Centre to X,Y Coordinates: Right Click Mouse

Move X,Y Coordinates to Center: Left Click Mouse

X-axis: expand the scale with + key; compress it with - key

Y-axis: expand the scale with key e; compress it with c

Start again and flip between logarithmic and linear = key f

Quit the programme = key q

Quit help screen = press any key

Screenshots: Here's a screenshot of data from a system that has grown from the late 1800's to 2007. By pressing the f key you can flip to logarithmic Y scale and this screenshot shows the same century long data as a truly organic exponential system. Actually I wrote Preview so I could study the features in these data.

That's all folks. The best way to use it is to try it.

Swerdna. 10 march 2008.