gnuplot-py-users

[Gnuplot-py-users] Using binary file with python-gnuplot

[Sean M. <sma...@gm...>]

Hi,

I would just like to report my experience / trouble so that others may find
solace if they have a similar problem.

I have code which makes a basic 2 dimensional Gaussian function. I want to
make a basic surface plot of this function, just to see what it looks like.
I have found that using Gnuplot.GridData function with the optional
filename argument enabled, so that it creates a permanent file, works. If I
leave out the "filename=test.bin" option, the program defaults to the
temporary FIFO class, and Gnuplot (4.6) is unable to read and properly
facorize the matrix.

My code, as a sample:

[code]
#!/usr/bin/python2

import Gnuplot
import numpy as np

g1 = Gnuplot.Gnuplot(debug=1)
#Let's try making a single contour plot of a windowing function, using
#Gnuplot.
t = np.linspace(-1000, 1000,2001) / 1e5
tc = 0.004
ts = t
[Xg,Yg] = np.meshgrid(ts, ts)
corr2win = np.exp(-(Xg/tc)**2 - (Yg/tc)**2 - (Xg * Yg) / (tc)**2)
#Plot the window using GNUPlot.
g1.title('2 Dimensional Windowing Function')
g1('set parametric')
g1('set dgrid3d 20, 20, 1')
g1.xlabel('Time (s)')
g1('set hidden3d')
g1('set style data lines')
g1('set pm3d')
g1.ylabel('TIme (s)')
g1.splot(Gnuplot.GridData(corr2win, ts, ts, binary=1, filename='test.bin'))
[/code]

If I run the splot command without the filename flag in GridData, I get the
following error:

line 0: File doesn't factorize into full matrix

My relevant version information is (all x86_64 builds where applicable):
Kernel: x86_64 Linux 3.16.1-1-ARCH
Python2.7.8
Ipython 2.2.0
gnuplot 4.6
python2-gnuplot 1.8.3 (as found on the AUR:
https://www.archlinux.org/packages/community/any/python2-gnuplot/

Anyways, I'm just putting this out since I didn't find anyone else with a
similar problem. Hope this helps.

Cheers,
Sean

Re: [Gnuplot-py-users] Using binary file with python-gnuplot

[Michael H. <mh...@al...>]

On 09/08/2014 02:38 AM, Sean Mattingly wrote:
> I would just like to report my experience / trouble so that others may
> find solace if they have a similar problem.
> 
> I have code which makes a basic 2 dimensional Gaussian function. I want
> to make a basic surface plot of this function, just to see what it looks
> like. I have found that using Gnuplot.GridData function with the
> optional filename argument enabled, so that it creates a permanent file,
> works. If I leave out the "filename=test.bin" option, the program
> defaults to the temporary FIFO class, and Gnuplot (4.6) is unable to
> read and properly facorize the matrix.

Problems like this could occur if the FIFO gets deleted too soon or the
Python thread that is supposed to write into the FIFO is killed too
soon. Does the problem go away if you put a long call to time.sleep
after the plot command?

It is also possible that newer versions of Gnuplot want to read through
the file twice. This would be incompatible with the FIFO code, which is
only prepared to write the content into the FIFO a single time.

Michael

-- 
Michael Haggerty
mh...@al...

Re: [Gnuplot-py-users] Using binary file with python-gnuplot

[Sean M. <sma...@gm...>]

The problem is still there if I put in a long call (5 - 10 seconds) to
time.sleep after the plot. I am running this within a python interpreter,
so the python thread gets to run as long as it needs.

Just to mess around a bit more, I also tried it by putting it within a file
then running it from the shell, with something like

$ python2 analysis.py

And I'm still getting the same factorize error.



On Mon, Sep 8, 2014 at 7:47 AM, Michael Haggerty <mh...@al...>
wrote:

> On 09/08/2014 02:38 AM, Sean Mattingly wrote:
> > I would just like to report my experience / trouble so that others may
> > find solace if they have a similar problem.
> >
> > I have code which makes a basic 2 dimensional Gaussian function. I want
> > to make a basic surface plot of this function, just to see what it looks
> > like. I have found that using Gnuplot.GridData function with the
> > optional filename argument enabled, so that it creates a permanent file,
> > works. If I leave out the "filename=test.bin" option, the program
> > defaults to the temporary FIFO class, and Gnuplot (4.6) is unable to
> > read and properly facorize the matrix.
>
> Problems like this could occur if the FIFO gets deleted too soon or the
> Python thread that is supposed to write into the FIFO is killed too
> soon. Does the problem go away if you put a long call to time.sleep
> after the plot command?
>
> It is also possible that newer versions of Gnuplot want to read through
> the file twice. This would be incompatible with the FIFO code, which is
> only prepared to write the content into the FIFO a single time.
>
> Michael
>
> --
> Michael Haggerty
> mh...@al...
>
>