Add new plot style: stackplot #819

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dmcdougall commented Apr 7, 2012

This addresses issue #359.

There is also an example so you can try out the pull request. Sample output from this code is provided below:


Feedback is greatly appreciated, as always.


dmcdougall commented Apr 7, 2012

Hooray, only two commits this time!


piti118 commented Apr 11, 2012


@mdboom mdboom commented on the diff Apr 13, 2012

+import numpy as np
+import matplotlib
+__all__ = ['stackplot']
+def stackplot(axes, x, y):
+ """Draws a stacked area plot.
+ Parameters
+ ----------
+ *x* : 1d array of dimension N
+ *y* : 2d array of dimension MxN

mdboom Apr 13, 2012


We should probably clarify here what's in the comment below: that the data is not "pre-stacked".

It might also be nice for y to be either a 2d array of MxN, or a variable number of y arguments (which would be stacked implicitly here).

@mdboom mdboom commented on an outdated diff Apr 13, 2012

+ element in the stacked area plot.
+ """
+ y = np.atleast_2d(y)
+ # Assume data passed has not been 'stacked', so stack it here.
+ y_stack = np.cumsum(y, axis=0)
+ r = []
+ # Color between x = 0 and the first array.
+ r.append(axes.fill_between(x, 0, y_stack[0,:],
+ # Color between array i-1 and array i
+ for i in xrange(len(y)-1):
+ r.append(axes.fill_between(x, y_stack[i-1,:], y_stack[i,:],

mdboom Apr 13, 2012


A nice bonus might be the ability to pass in a kwarg with a list of colors if the user wants to override the color defaults.


mdboom commented Apr 13, 2012

This is great! Barring my minor comments, I think this is good to go. (And I think the color thing could be done as a second step if necessary -- my other comments are more important, IMHO).


dmcdougall commented Apr 14, 2012

Thanks for your feedback @mdboom. GitHub is great for code review and feedback. I love it.

None of these most recent commits include the colors keyword argument functionality you mentioned. I figured I could do that at a later time.


mdboom commented Apr 16, 2012

I think this is ready to merge. Will leave it up for a few more days in case others would like to comment.


WeatherGod commented Apr 16, 2012 needs update, as well as some docs (front page, what's new and API changes). I haven't looked over the docstrings yet.


dmcdougall commented Apr 16, 2012

I've been trying to figure out what @WeatherGod means by ' needs an update'. I think I figured it out.

I add stackplot to the _plot_commands variable and run Then I tested the stackplot function using pylab. I get the following error:

'NoneType' object has no attribute 'pop'.

I then spent an hour trying figure out what was going wrong. Long story short:

  1. stackplot has no argument **kwargs;
  2. as a result, adds the line: hold = None.pop('hold', None) to the stackplot method in

How should I deal with this? Deleting it manually is not a solution because any time anybody else runs boilerplate the same thing will happen. Maybe I should just add a **kwargs argument and pass them to all the called Axes.fill_between methods in stackplot. The bonus there is that stackplot would then support things like alpha, linewidth and facecolor. Also, I plan to add support for custom coloring, so it will inevitably be added in the future.


mdboom commented Jun 1, 2012

This perhaps should be re-evaluated in relation to the related PR #847.

The example should be converted into a unit test.

Other than that, this looks generally good to me.


WeatherGod commented Jun 7, 2012

It does appear to need a rebase at the very least. Most likely due to changes in


dmcdougall commented Jun 7, 2012

You mean you want me to rebase against current master? I can do that. Are there any changes you wish me to make before I rebase?


WeatherGod commented Jun 7, 2012

Changes before rebasing would only complicate things. There still remains discussion regarding design decisions, but at least we would have a working branch to refer to in this manner.


dmcdougall commented Jun 7, 2012

I've rebased against master.


pelson commented Jun 18, 2012

@dmcdougall: Unfortunately this will need rebasing again due to some changes to the boilerplate script. It is possible that you will get conflicts there and in the actual pyplot file. The good news is that you can now simply run and it automatically updates pyplot for you.

Once you have done that, and added the example code as a simple unit test, I will merge the PR. Great work!

dmcdougall added some commits Apr 7, 2012

@dmcdougall dmcdougall Added new plot style: stackplot.
Stackplot adds the feature request in issue #359
(matplotlib#359) and borrows
heavily from Doug Y'barbo's stackoverflow answer
@dmcdougall dmcdougall Added stackplot example. 4557573
@dmcdougall dmcdougall Make docstring more helpful.
The data *y* is assumed to be unstacked. This is now explicitly said in
the docstring for the paramater *y*.
@dmcdougall dmcdougall Make stackplot take an arbitrary number of args.
stackplot now supports taking either an MxN array of data, stacking
along axis=0, or an arbitrary number of 1xN arrays, stacking them in the
order passed.

No checks are done for the case when no the number of args is zero. An
exception should probably be raised here.

Updated docstring to explain new call signatures.
@dmcdougall dmcdougall Updated stackplot example.
Stackplot example now reflects usage of variadic calling signature.
@dmcdougall dmcdougall Update changelog to include stackplot. 3e8fe6e
@dmcdougall dmcdougall Stackplot now supports the same keyword aargs as matplotlib.Axes.fill…

This is a measure to make not produce a file
with syntax errors. It's also a sensible course of action considering
new stackplot features will almost certainly require keyword arguments
@dmcdougall dmcdougall Fixed an issue where stackplot didn't fill stacked data in correct or…
@dmcdougall dmcdougall Added stackplot to list of pyplot commands. now contains the necessary information to make stackplot work
inside of pyplot.
@dmcdougall dmcdougall Added support for custom colour cycle.
New keyword argument 'colors' can be passed to allow custom colouring of
the stacked areas in a stacked area plot.
@dmcdougall dmcdougall Add stackplot to list of plotting commands. a3a35fb

dmcdougall commented Jun 19, 2012

@pelson Thanks for the feedback. I've rebased and saw a conflict in I fixed everything. I'm currently at a conference stuck behind a router that blocks all ports except 80 and 443. I will push the changes as soon as I am behind a reasonable router.


dmcdougall commented Jun 19, 2012

Aha! I ninja pushed through a proxy. All sorted now!

pelson was assigned Jul 1, 2012


pelson commented Jul 5, 2012

@dmcdougall: Ideally, I would just like to get a unittest added and then I can press the big green merge button ;-)

@dmcdougall dmcdougall Added stackplot unit test.
Test images added. Unit test writted and unit test added to default
tests in

dmcdougall commented Jul 5, 2012

Done. Let me know if I messed anything up. I followed the guidelines here.



pelson commented Jul 6, 2012

Don't think you need the stackplot_test_image_pdf.png file.


dmcdougall commented Jul 6, 2012

I have no idea why that was there; the test produced it. Maybe because I am using the pdf backend by default? Anyway, it's gone.


pelson commented Jul 7, 2012

So the tests, by default, produce a png, a svg and a pdf, but in order to do the test comparison they are rasterised into <fname>_svg.png and <fname>_pdf.png, the latter two don't need to be in the baseline directory. Will merge in 24 hrs.

@pelson pelson added a commit to pelson/matplotlib that referenced this pull request Jul 28, 2012

@pelson pelson Merged #819: dmcdougall's stackplot 5675ffa

pelson commented Jul 28, 2012

I merged this manually to mpl. I moved your test into the test_axes module and squashed the commits into one (see 5675ffa).

Thanks for all your work (and patience) on this PR.

pelson closed this Jul 28, 2012

pelson referenced this pull request Aug 19, 2012


new plot style: stackplot #359

Is there a way to remove the black lines between the polygons?

Oh, yeah, this will do it:

fbk = {'lw':0.0, 'edgecolor':None}
plt.stackplot(x, y.T, **fbk)

Stackplot currently takes Y in a transposed format.. should that be fixed?


jenshnielsen commented Aug 18, 2015

Well transposed or not depends on the layout of your data. This is probably not the best place to discuss such changes. Comments on an old closed issue/PR are likely to be lost. If you want to suggest changes please either use the mailing list or create a new open issue/PR

Ok, done: #4952

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