Stem is slow and will crash if I try to close the window

Bug summary

Stem will crash if you try to close the window while it's processing. It's also very slow for what I would consider a relatively small number of data points. I'm using the code from Julia, but I was informed the problem is Matplotlib. See original discusion.

Code for reproduction

using PyPlot
stem(randn(32768))

Actual outcome

This will work if you wait about half a minute. If you interfere by trying to close the window, the application crashes (Julia in this case).

Matplotlib version

I don't know. I'm using the most recent version of PyPlot and PyCall in Julia 0.5. Conda installed Python 2.7.

Can you please provide python code that generate the issue? As the julia folks point at us, it is not clear that this is not a bug on the julia side.

I tried just now. I'm afraid I'm too much of a beginner with both Julia and Matplotlib to figure this out. However, poster jheinen on the Julia forum claims to have reproduced this problem in pure Python. I suggest asking him for his code. I'm sorry I can't be of any more help. I don't want to get in the middle of any finger pointing between these two communities.

@jheinen

It is not finger pointing, just sorting out what the actual bug is.

attn @jheinen

This is how you can reproduce the bug (in Python)

import matplotlib.pyplot as plt
import numpy as np
plt.stem(np.random.randn(10000))

Fails on macOS X, can't check other backends before Monday ...

Indeed, this is likely due to the fact that stem generates one Line2D per stem, rather than grouping everything in a LineCollection, which would probably improve the performance quite a bit.

(but LineCollection currently cannot take a custom marker :-()

At a minimum, we could save some time by not going through plot

Having a look at this and think I'm making progress

I also confirmed this bug in Python 3 on Ubuntu 16.04. I tried to plot a stem plot with 130,000 points and the computer crunched on it a long time without displaying anything.

Since I encountered this problem by plotting around 30000 data points today I found this issue.
I can only link to this workaround I found, which solved my problem through manually calculating the line, coordinates and plotting a line collection, instead of using stem itself.
https://stackoverflow.com/questions/48301044/optimization-of-matplotlib-stem-plot
Maybe it helps someone.

Will this be merged to some 3.0.x version, or do we need to wait for stable 3.1.x version if we want this fixed in pip?

I'm afraid this is only going to be in 3.1.x onwards.

But 3.1.0 should hopefully come out soon 😄 .

Hopefully today or tomorrow.

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Stem is slow and will crash if I try to close the window #7969

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Stem is slow and will crash if I try to close the window #7969

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tacaswell commented on Jan 28, 2017

goldfita commented on Jan 28, 2017

tacaswell commented on Jan 28, 2017

jheinen commented on Jan 28, 2017

anntzer commented on Jan 28, 2017

anntzer commented on Feb 16, 2017

tacaswell commented on Feb 17, 2017

dstansby commented on Oct 24, 2017

terriyu commented on Feb 1, 2018

grr37213 commented on Aug 16, 2018

racinmat commented on May 15, 2019

dstansby commented on May 15, 2019

timhoffm commented on May 15, 2019

tacaswell commented on May 15, 2019

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