Matplotlib save to pdf not showing hatch marks in bar plot — potential bug?

[vkidamisc]

Bug report

I am using matplotlib version 3.1.1 on an ubuntu 18.04 machine and have tried this code in both python 3.6.8 and 3.7.4 on 2 different boxes.

The problem is that when there are more than 10 items the color repeats itself and I made a quick change to make hatch marks to differentiate. While this works well in display, the hatches do not show up when I savefig("*.pdf"). savefig("*.png") seems to work fine as seen in the figures below.

I have searched for this issue in multiple places but can't seem to find a solution that works. I have also tried PdfPages.

Simple code and output are attached below. I appreciate any suggestions.

Code for reproduction

import matplotlib
import matplotlib.pyplot as plt
import pandas as pd

matplotlib.__version__  #3.1.1
df=pd.DataFrame({'A':[0.1]*12, 'B':[0.1]*12}).T
tit='title'

ax=df.plot.bar(figsize=(11,8.5),stacked=True,title=tit)
nrows=len(df)
bars = ax.patches
hatches=['','-', '+', 'x','/','//','O','o','\\','\\\\']*nrows*10 #times rows*colors
#
hatches.sort()
hatches=hatches[0:len(bars)]
i=0 
for bar in bars:# goes down a column with same color,  then next with diff color and so on.  
    bar.set_hatch(hatches[i])
    #bar.text('1')
    #print(bar)
    i+=1    
ax.legend(#loc='lower center', loc='upper center',bbox_to_anchor=(0.5, -.05,0,0),fancybox=True, shadow=True, ncol=5,fontsize=5.5)

#plt.savefig('barhatch.png')   

plt.savefig('barhatch.pdf')   

This is the output I get. Note that the hatch marks are missing. This happens when writing pdf.

This is the output when I save as png, which correctly shows the hatch marks.

Matplotlib version

• Operating system: Ubuntu 18.04
• Matplotlib version: 3.1.1
• Matplotlib backend (print(matplotlib.get_backend())): Qt5Agg
• Python version: 3.6.8 & 3.7.3
• Jupyter version (if applicable):
• Other libraries:

Installed using pip3

[anntzer]

I can confirm; this only happens with pdf and not ps or svg, and not with mplcairo either.

[timhoffm]

Possibly duplicate of #12367.

[anntzer]

I could repro some of #12367 with mplcairo, but none of this, so I'm not 100% sure it's a dupe.

[georgedeath]

As per https://stackoverflow.com/a/59389823/2161490, using alpha=0.99 is a viable workaround.

[github-actions]

This issue has been marked "inactive" because it has been 365 days since the last comment. If this issue is still present in recent Matplotlib releases, or the feature request is still wanted, please leave a comment and this label will be removed. If there are no updates in another 30 days, this issue will be automatically closed, but you are free to re-open or create a new issue if needed. We value issue reports, and this procedure is meant to help us resurface and prioritize issues that have not been addressed yet, not make them disappear. Thanks for your help!

[Impaler343]

I cannot reproduce this on the current master, has this already been solved?

[tacaswell]

I agree this one looks solved. Might be worth back-tracking to figure out when but going to milestone to 3.8

import matplotlib
import matplotlib.pyplot as plt
import pandas as pd
import itertools

matplotlib.__version__  #3.1.1
df=pd.DataFrame({'A':[0.1]*12, 'B':[0.1]*12}).T
tit='title'

ax=df.plot.bar(figsize=(11,8.5),stacked=True,title=tit)
nrows=len(df)
bars = ax.patches
hatches=['','-', '+', 'x','/','//','O','o','\\','\\\\']
#
hatches.sort()
hatches=hatches[0:len(bars)]
i=0
for hatch, bar in zip(itertools.cycle(hatches), bars):# goes down a column with same color,  then next with diff color and so on.
    bar.set_hatch(hatch)

ax.legend(loc='upper center',bbox_to_anchor=(0.5, -.05,0,0),fancybox=True, shadow=True, ncol=5,fontsize=5.5)

plt.savefig('/tmp/barhatch.pdf')

is a slightly modified test case.