The Lab Book Pages

An online collection of electronics information

Dr. Andrew Greensted
Last modified: 8th October 2015

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Gnuplot is an excellent free tool for plotting graphs. This page is just a collection of techniques I use regularly. The links section has suggestions for other, more comprehensive gnuplot sites.

There are many good gnuplot websites. Below is a list of some that contain useful information


Gnuplot Point Styles

Gnuplot Point Styles

Heatmap Plots

The simplest method for creating a heatmap is to organise your data in a list of x,y,z values. The x and Y values are the positions in the heatmap. The z value will set the colour of the block at the x,y coordinate. A snippet of a data file is shown below. The first data value line defines a point at x,y = -15,11 with a data value of 0.020394. Note that the x,y values do not need to be integers.

File Excerpt: map.dat
-15 11 0.020394
-15 12 0.015745
-15 13 0.011885
-15 14 0.008771
-15 15 0.006330
-14 -15 0.008771
-14 -14 0.012155
-14 -13 0.016469
-14 -12 0.021818

Using the complete data file heatmap.dat, the heatmap can be plotted using the following gnuplot command.

plot 'heatmap.dat' u 1:2:3 with image
Heatmap created with Gnuplot

Heatmap created with Gnuplot

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