问题
See this article Enclosed, but not Encrypted.
I have some binary data. I want to perform the gnuplots shown in that article, but using my data.
For a three-dimensional phase-space plot, the sequence a, b, c, d, e, f, etc. can be used as space coordinates (a-b, b-c, c-d), (b-c, c-d, d-e), (c-d, d-e, e-f), etc. Patterns in the plot created reveal recurring relations between subsequent sequences. In this phase plot, 50,000 16-bit random numbers would produce an unstructured cloud of dots.
I want to do exactly the same kind of thing. I have a binary file (about 10 MB) and I'd like to run it through gnuplot to create the nice gnuplot graphs.
What do I type into gnuplot to make that happen?
Doing a Google search for "phase space plot" and gnuplot doesn't return much. I don't know if that's because the article is a translation from German. I don't think I've found relevant answers in stack exchange sites.
回答1:
To plot the 3d phase space use the following script, which works like the running average example from the gnuplot page:
reset
back4 = back3 = back2 = back1 = 0
shift(x) = (back4 = back3, back3 = back2, back2 = back1, back1 = x)
samples(x) = $0 < 3 ? NaN : x
set ticslevel 0
# the labels are only for orientation when checking the test data
set xlabel 'xlabel'
set ylabel 'ylabel'
splot 'randomdata.dat' using (shift($1), samples(back4-back3)):(samples(back3-back2)):(samples(back2-back1))
Gnuplot must hold four data values, which are stored in back1 to back4. For every new value, the stored values are shifted with shift. samples takes care that the first three values are not used, but only stored (NaN creates an invalid data point).
To test it, use this file randomdata.dat:
21
15
10
6
3
1
0
This plots four data points at (6,5,4), (5,4,3), (4,3,2), and (3,2,1).
If you have a binary data file with e.g. 16bit numbers, use
splot 'binaryfile' binary format="%ushort" using (shift($1), samples(back4-back3)):(samples(back3-back2)):(samples(back2-back1))
If you need to change the datasize, invoke gnuplot and type show datafile binary datasizes to see which formats are supported.
来源：https://stackoverflow.com/questions/17892901/how-do-i-create-a-3d-phase-space-plot-in-gnuplot