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mizzao opened this issue Feb 23, 2015 · 4 comments · Fixed by #34514
Closed

Asymmetric error bars are not supported for series (only dataframes) #9536

mizzao opened this issue Feb 23, 2015 · 4 comments · Fixed by #34514
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good first issue Visualization plotting
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1.1

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@mizzao
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mizzao commented Feb 23, 2015

According to the documentation, asymmetric error bars should be able to be passed in to plot as an Mx2 array for a Series object or a Mx2xN array for a DataFrame object.

However, the code only seems to parse this correctly for a DataFrame: https://github.com/pydata/pandas/blob/master/pandas/tools/plotting.py#L1338

When passing raw error values as yerr, it seems that the first values are used as two-sided error differences, instead of being plotted as raw upper and lower values. Note the symmetric error bars below:

image

Using the underlying matplotlib function directly yields the expected results, but without the pandas-generated decorations:

image

This was originally noted in this StackOverflow question and I corroborated the other user's experience.
@ericmjl
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ericmjl commented Nov 3, 2015

I am having a similar issue here.

@TomAugspurger TomAugspurger added the Visualization plotting label Nov 3, 2015
@TomAugspurger TomAugspurger added this to the 0.18.0 milestone Nov 3, 2015
@TomAugspurger
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Anyone interested in submitting a fix? I can help you out if you run into trouble.

@ericmjl
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ericmjl commented Nov 3, 2015

I'm happy to try!

@TomAugspurger: I've been a user of pandas for a while, but I think I might need some guidance to the codebase. Would you be kind enough to pinpoint roughly where I should get started?

@TomAugspurger
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Thanks!

The plotting code is all in pandas/tools/plotting.py The logic for parsing error bars should all be here so that's were I'd start.

@kleingeist kleingeist mentioned this issue Jan 19, 2016
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@jreback jreback modified the milestones: 0.18.1, 0.18.0, Next Major Release Feb 10, 2016
kleingeist added a commit to kleingeist/pandas that referenced this issue Apr 2, 2016
@kleingeist
Fix asymmetric error bars for series (closes pandas-dev#9536)
89f3d98 
This fix is for handling asymmetric error bars for series.
It adapts to the syntax for
http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.errorbar
where a sequence of shape 2xN is expected in case of asymmetric error bars.

If a single series is to be plotted and the error sequence is of shape 2xN
it will be used as asymmetric error bars.
Previously a 2xN error sequence was assumed to be 2 symmetric error sequences
for 2 series. Thus in the end only the first error sequence was used.

This commit improves the docstring of the `_parse_errorbars` method as well
as the general pandas doc on error bars.
@diazona diazona mentioned this issue Aug 23, 2016
Closed
@Steffen911 Steffen911 mentioned this issue Jun 1, 2020
Merged
@jreback jreback modified the milestones: Contributions Welcome, 1.1 Jul 17, 2020
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good first issue Visualization plotting
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@jreback @TomAugspurger @mizzao @ericmjl @jbrockmendel