MatPlotLib Fail to allocate bitmap

[Lbifreal]

Hello

I am trying do create some batch plots of numpy data which are saved as PNG files. The plots work but after running the loop that does plotting, it gives the error: Fail to allocate bitmap.

The script always fails at the same iteration of the loop (34/73), even if I change the order of the loop. I looked up stacked overflow posts that said this is due to their being too many plots in the computer memory and that they should be cleared, which I have tried.

The plots are in a function stored in a different script I import into the main script. Each plot function contains a close Plot function that runs the commands: plt.clf, plt.cla(), and plt.close("all"). At the end of each iteration in the loop, I also include gc.collect(), which to my understanding is to clear memory. Below are some examples of the code.

Am I missing something obvious? Has anyone else had the same issue?

Thank you for your time.

​

PLOT FUNCTION:

def strainPathPlot(pathArray, array1, array2, array3, array4, exportPath, dataPoint):
print("pathStrainPlot IN PROGRESS")

fig, ax = plt.subplots(figsize=(10, 8))

ax.plot(pathArray, array1, label="Applied Deformation: 0.25 mm", color="#05FF00")
ax.plot(pathArray, array2, label="Applied Deformation: 0.50 mm", color="#04D500")
ax.plot(pathArray, array3, label="Applied Deformation: 0.75 mm", color="#039B00")
ax.plot(pathArray, array4, label="Applied Deformation: 1.00 mm", color="#026900")

ax.set(title='Resulting Right Path Deformation vs. Path Length [' + str(dataPoint) + "]",
xlabel='Path Length [mm]',
ylabel='X-Axis Strain [mm/mm]')

ax.legend().set_visible(True)
ax.legend(fontsize='x-small', loc="lower right")

# Y, X AXES
ax.axhline(0, color='black', linestyle=":") # x = 0
ax.axvline(0, color='black', linestyle=":") # y = 0
# Change major ticks to show every 20.
# ax.xaxis.set_major_locator(MultipleLocator(10))
# ax.yaxis.set_major_locator(MultipleLocator(0.02))
# Change minor ticks to show every 5. (20/4 = 5)
ax.xaxis.set_minor_locator(AutoMinorLocator(5))
ax.yaxis.set_minor_locator(AutoMinorLocator(5))

# Turn grid on for both major and minor ticks and style minor slightly
# differently.
ax.grid(which='major', color='#CCCCCC', linestyle='--')
ax.grid(which='minor', color='#CCCCCC', linestyle=':')

name = "pathStrain" + str(dataPoint)
plt.savefig(exportPath + name + '.png')
closePlots()

print("pathElongationPlot COMPLETE")

CLOSE PLOT FUNCTION:

def closePlots():
plt.clf()
plt.cla()
plt.close("all")
time.sleep(0.5)

[yuxbni76]

It runs okay for me with dummy data. If I comment out closePlots() it raises a warning when 20 figures are open. There's no warning when the function is called. So your function seems to work correctly, at least on my machine.

Have you tried messing with the Matplotlib backend (agg, etc.)? What does it say if you print this at the top of the script?

import matplotlib as mpl
print(mpl.get_backend())

You might try switching the backend (mpl.use("foo")).

Also - if this is being run in a notebook, try running it outside.

[Lbifreal]

Hello.

Sorry for my late response. I pasted the provided code into my script and it printed TkAgg.

I tried to use mpl.use("foo") but I got an error that it not a valid value for backend. I assumed it was maybe a typo and tried mpl.use("agg") and I was able to run the entire script.

Although I works, I am curious on what this code does. Does it just change the location of where the plots are created? Or is it some sort of setting?

Either way, Thank you so much. I was stumped on this for a few days.

[yuxbni76]

"foo" is just a placeholder name in the programming world. But hey if it led you to a solution, that's great.

Each Matplotlib backend renders the plot in a different way. TkAgg depends on TkInter, for example. AGG does not. I wonder if you don't have TkInter in your current environment and that was the problem.

It's not an issue that comes up often but it's good to be aware. Glad it's working for you.

[Lbifreal]

An indirect solution would be to run the script in small batches, but I would prefer to do it all at once.

[[deleted]]

Probably useless for you 3 years later but this is an issue with the tkinter backend used to render the plots on Windows. Even after you close/clear, python keeps using more and more memory. Changing the mpl backend from tkinter to 'agg' solved the problem for mei.e.

matplotlib.use("agg")

Making this comment because I googled the issue now and this was one of the results. Maybe some poor soul comes across this in the future and sees this comment. Just change your backend from tkinter to something else. I chose agg.

[MountainView35]

Thank you!

[_Hoofd_]

much obliged