Python: conditional color in barplot

Question

I'm doing an horizontal barplot. I need one specific bar (type=milk) to have a green fill color, and gray for the other types. The dataframe is:

df = DataFrame(val  = c(1, 2, 3, 6, 7, 8),
                type = c("honey","bread","coffee","bread","honey","milk"))

I have tried this without success:

clrs = ['green' if ((x == milk) else 'gray' for x in type]
ax.barh(df['type'], (df['val']), align='center', colors=clrs)

Any ideas?

Vaaal88 · Accepted Answer · 2020-07-05 19:46:12Z

1

Yes, you could change the patch of the appropriate bar, something like

b=ax.barh(df['type'], (df['val']), align='center', colors=clrs)

b.patches[4].set_color('green')

However I don't understand why you are repeating the same labels multiple times.

If you didn't have repeated elements you could find the label milk automatically like this:

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
plt.close('all')
df = pd.DataFrame({'val': np.array([1, 2, 3, 6]), 'types': ["honey", "coffee", "bread","milk"]})

b = plt.barh(df['types'], df['val'], align='center', color='gray')
index_milk = df[df['types']=='milk'].index[0]
b.patches[index_milk].set_color('green')
plt.show()

answered Jul 5, 2020 at 19:46

Vaaal88

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5 Comments

user284437 Over a year ago

Some labels repeat since in the full dataframe, some of them do. Just trying to better reproduce the issue.

Vaaal88 Over a year ago

if labels repeat you will have a problem that does not relate to the color. My answer should solve the color problem though, right?

Vaaal88 Over a year ago

could you accept it if it solved your problem? If it didn't, could you say why it didn't? Thanks

user284437 Over a year ago

Hi Vaaal88. One last question. Let's say I have 500 labels in my dataframe and some of them repeat, is there a way to use b.patches and the name of the label? Something like b.patches[df('milk')]. Thank you.

Vaaal88 Over a year ago

the problem is that, in pandas, when a label repeats, only the last one is plotted, so there will be an object 'patches' only for the last bar. That's why I told you it's a problem to have repeated elements. Conceptually, what does it mean? Bread has a value of 2 and a value of 6? Maybe if you clarify this point I can help you out

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