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Gnuplot to plot histogram

GNUPLOT can be used to generate histograms.
The script below allows one to plot variations in angle from 0° to 180°.
Each histogram box width correspond to 3° (covered here under bw option).
To execute this script; type this in the terminal:


gnuplot histogram.p

You should be in the folder where below script is saved in a file name "histogram.p" and a dat file (here, it is N---H-O.dat) should be present.

histogram.p
------------------
set term gif
set output "angle_N---H-O.gif"
set xrange [0.0:180.0]
set boxwidth 2.0 absolute
set style fill solid 1.0 border -1
set xtics 10
set title "molecule 3.0A Angle N---H-O"
set ylabel "occurance"
set xlabel "angle"
bw = 3   # substitute what you want
bin(x,width)=width*floor(x/width)
plot 'N---H-O.dat' using (bin($2,bw)):(1.0) smooth freq with boxes

------------------

The dat file is an input file with data in the format:
0    23.680344
1    73.766251
2    67.482254
3    52.086418
4    72.886803
5    54.009365
6    36.297497
7    35.184067
8    162.915512
9    52.081470
10    49.975559
11    46.514202
12    45.990093 ..............

Two columns where the second column refers to bond angles. First column here gives molecular dynamics steps.

On execution a gif file (here,angle_N---H-O.gif) will be created which looks something like this:


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