gnuplot documentation

33 IMAGE gnuplot 4.3 47
This will produce a plot in which each vertical bar
corresponds to one row of data. Each vertical bar
contains a stack of two segments, corresponding in
height to the values found in columns 2 and 4 of the
datafile.
10
8
6
Rowstacked
ClassB
ClassA
Finally, the commands
set style histogram columnstacked
plot ’file.dat’ using 2, ’’ using 4
4
2
0
will produce two vertical stacks, one for each column
Columnstacked
18
of data. The stack at x=1 will contain a box for each 16
entry in column 2 of the datafile. The stack at x=2 14
will contain a box for each parallel entry in column 4 12
of the datafile. Because this interchanges gnuplot’s 10
usual interpretation of input rows and columns, the 8
specification of key titles and x-axis tic labels must 6
4
also be modified.
2
set style histogram columnstacked
0
plot ’’ u 5:key(1)
# uses first column to generate ClassA key ClassB titles
plot ’’ u 5 title columnhead # uses first row to generate xtic labels
32.1 Newhistogram
More than one set of histograms can appear in a single plot. In this case you can force a gap between
them, and a separate label for each set, by using the plot command newhistogram {""}
{}. For example
set style histogram cluster
plot newhistogram "Set A", ’a’ using 1, ’’ using 2, ’’ using 3, \
newhistogram "Set B", ’b’ using 1, ’’ using 2, ’’ using 3
The labels "Set A" and "Set B" will appear beneath the respective sets of histograms, under the overall
x axis label.
The newhistogram command can also be used to force histogram coloring to begin with a specific color
(linetype). By default colors will continue to increment successively even across histogram boundaries.
Here is an example using the same coloring for multiple histograms
plot newhistogram "Set A" lt 4, ’a’ using 1, ’’ using 2, ’’ using 3, \
newhistogram "Set B" lt 4, ’b’ using 1, ’’ using 2, ’’ using 3
32.2 Automated iteration over multiple columns
If you want to create a histogram from many columns of data in a single file, it is very convenient to
use the plot iteration feature. See iteration (p. 78). For example, to create stacked histograms of the
data in columns 3 through 8
set style histogram columnstacked
plot for [i=3:8] "datafile" using i title columnhead
33 Image
The image style is intendend for projecting 2D images onto either 2D or 3D plots. It may be used for
both plot and splot in the form of 3D data (x,y,value) or projected 4D data (x,y,z,value), respectively.
It is assumed that in the viewing plane the image data forms an equidistant sampling grid in the viewing