CODEWITHSUNDEEP
pythonpandasmatplotlibplotbar-chart
Nikki101
Nikki101

Reputation: 69

Plotting bar chart -colors python

I have a pandas dataframe that I want to plot as a barchart the data has the following form; 

Year   ISO  Value   Color 
2007   GBR  500     0.303
       DEU  444     0.875  
       FRA  987     0.777
2008   GBR  658     0.303
       USA  432     0.588  
       DEU  564     0.875
2009 ... etc

i tried to iterate over the data in the follow way; 

import matplotlib.pyplot as plt
import matplotlib.cm as cm 


conditions=np.unique[df['Color']]
plt.figure()
ax=plt.gca()
for i,cond in enumerate(conditions):
     print 'cond: ',cond
     df['Value'].plot(kind='bar', ax=ax, color=cm.Accent(float(i)/n))


     minor_XT=ax.get_xaxis().get_majorticklocs()
     df['ISO']=minor_XT
     major_XT=df.groupby(by=df.index.get_level_values(0)).first()['ISO'].tolist()
     df.__delitem__('ISO')
     plt.xticks(rotation=70)
     ax.set_xticks(minor_XT, minor=True)
     ax.set_xticklabels(df.index.get_level_values(1), minor=True, rotation=70)
     ax.tick_params(which='major', pad=45)
     _=plt.xticks(major_XT, (df.index.get_level_values(0)).unique(), rotation=0)
     plt.tight_layout()
     plt.show()

But it all out in one color, any suggestions as to what I am doing wrong?

Upvotes: 3

Views: 1388

Answers (1)

tmdavison
tmdavison

Reputation: 69223

Since df['Value'].plot(kind='bar') will plot all your bars, you do not need to iterate over you conditions. Also, as plot(kind='bar') essentially calls matplotlib.pyplot.bar, we can feed it a list of colors of the same length as our data array, and it will color each bar using those colors. Here's a slightly simplified example (I'll leave you to figure out the ticks and tick labels):

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

df = pd.DataFrame([
    [2007,'GBR',500,0.303],
    [2007,'DEU',444,0.875],
    [2007,'FRA',987,0.777],
    [2008,'GBR',658,0.303],
    [2008,'USA',432,0.588],
    [2008,'DEU',564,0.875]],
    columns=['Year','ISO','Value','Color'])

colors = cm.Accent(df['Color']/len(df['Color']))

fig=plt.figure()
ax=fig.add_subplot(111)

df['Value'].plot(kind='bar',ax=ax,color=colors)

plt.show()

enter image description here

Upvotes: 2

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