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TD22057 opened this issue Feb 27, 2018 · 3 comments · Fixed by #10623
Closed

bar plot fails with units #10619

TD22057 opened this issue Feb 27, 2018 · 3 comments · Fixed by #10623
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topic: units and array ducktypes
Milestone
v2.2.0

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@TD22057
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TD22057 commented Feb 27, 2018

Bug report

ax.bar() fails if the input data has units. This is a fairly new bug as it worked fine at some point in the past. The exception is:

  /home/trd/work/git/matplotlib/build/lib.linux-x86_64-3.6/matplotlib/axes/_base.py:2500: RuntimeWarning: invalid value encountered in double_scalars
    delta = (x1t - x0t) * margin

The issue is that the unit conversion code is being run after a call to np.broadcast_arrays so that the x values are not actually arrays, they're still lists of units. The fix is re-order the code in bar() so that the unit conversion happens first.

Code for reproduction

I'll send in a pull request w/ a fix once I can get the right version of free type to install so I can run existing tests and create a baseline file. This occurs on the current master branch code.

New test case being added to test_units.py which will throw the exception:

@image_comparison(baseline_images=['jpl_bar_units'], extensions=['png'],
                  savefig_kwarg={'dpi': 60})
def test_jpl_bar_units():
    from datetime import datetime
    import matplotlib.testing.jpl_units as units
    units.register()
    day = units.Duration("ET", 24.0 * 60.0 * 60.0)

    x = [units.Epoch("ET", dt=datetime(2009, 4, 25)),
         units.Epoch("ET", dt=datetime(2009, 4, 26)),
         units.Epoch("ET", dt=datetime(2009, 4, 27))]
    width = [3*day, 2*day, 1*day]

    fig, ax = plt.subplots()
    ax.bar(x, width)
@TD22057
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TD22057 commented Feb 27, 2018

FYI: @jrevans

@jklymak
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jklymak commented Feb 27, 2018

Thanks for the potential PR: If you don't need the text for the test, you can call as:

@image_comparison(baseline_images=['jpl_bar_units'], extensions=['png'],
                  savefig_kwarg={'dpi': 60}, remove_text=True, style='mpl20')

Also, for new tests, we are trying to use 'mpl20'.

@tacaswell
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@TD22057 See https://matplotlib.org/devel/contributing.html?highlight=local_freetype#building-matplotlib-for-image-comparison-tests . I have export MPLLOCALFREETYPE=1 in my bashrc which will take care of downloading and building the correct version of freetype.

@tacaswell tacaswell added this to the v2.2.0 milestone Feb 27, 2018
TD22057 added a commit to TD22057/matplotlib that referenced this issue Feb 27, 2018
@TD22057
Fixes matplotlib#10619. Reordered bar plot to correctly handle units
daa4d20
@TD22057 TD22057 mentioned this issue Feb 28, 2018
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Fix for failing bar plot w/ units TD22057/matplotlib
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@tacaswell @TD22057 @jklymak @dstansby