Error when creating a bar chart in Matplotlib

Question

I would like to create a barchart in matplotlib with 3 bars for each of 12 weeks. I adopted a code for barcharts with two bars but unfortunately I get the following error message: "ValueError: shape mismatch: objects cannot be broadcast to a single shape "

Here is my code:

import matplotlib
import matplotlib.pyplot as plt
import numpy as np


labels = ['Woche \n 1', 'Woche \n 5', 'Woche \n 6', 'Woche \n 8', 'Woche \n 8' , 'Woche \n 11', 'Woche \n 12',
         'Woche \n 41', 'Woche \n 43', 'Woche \n 46', 'Woche \n 48', 'Woche \n 49', 'Woche \n 50']
conventional = [1063, 520, 655, 47, 1516, 3200, 1618, 1378, 577, 504, 76, 1154]
IC = [345, 217, 229, 0, 800, 2700 ,1253, 896, 151, 382, 4, 797     ]
CO = [100, 130,  80, 0, 580, 2450, 1020, 650, 0, 300, 0, 600    ]

x = np.arange(len(labels))  # the label locations
width = 0.30  # the width of the bars

fig, ax = plt.subplots(figsize=(13,8), dpi=100)
rects1 = ax.bar(x - width/2, conventional, width, label='conventional')
rects2 = ax.bar(x + width/2, IC, width, label='IC')
rects3 = ax.bar(x + width/2, CO, width, label='CO')

# Add some text for labels, title and custom x-axis tick labels, etc.
ax.set_ylabel('Surplus', fontsize = 17)
ax.set_xticks(x)
ax.set_xticklabels(labels)
ax.tick_params(axis='both', which='major', labelsize=16)
ax.legend(loc='center left', bbox_to_anchor=(0.07, 1.04), fontsize = 16, ncol=3)



fig.tight_layout()

plt.savefig('PaperA_Results_7kWp.png', edgecolor='black', dpi=400, bbox_inches='tight')

plt.show()

Can anyone tell me, what causes the error? I'd appreciate every comment.

You need to show the full traceback

roganjosh
– roganjosh

2020-06-07 20:32:55 +00:00
Commented Jun 7, 2020 at 20:32 — roganjosh
– roganjosh, Commented Jun 7, 2020 at 20:32

Sheldore · Accepted Answer · 2020-06-07 20:34:07Z

2

The problem is that you have 13 labels but your remaining arrays, conventional, IC and CO have only 12 values. That's why, when you do np.arange(len(labels)), you have 13 x-values but only 12 values for conventional, IC and CO which results in shape mismatch error. Perhaps you want to plot only the first 12 labels.

Also, I think you want to use the correct x-positions for your bars to show them side by side. Therefore, use the following code

x = np.arange(len(labels)-1)  # the label locations


width = 0.25
fig, ax = plt.subplots(figsize=(8, 6), dpi=100)
rects1 = ax.bar(x - width, conventional, width, label='conventional')
rects2 = ax.bar(x , IC, width, label='IC')
rects3 = ax.bar(x + width, CO, width, label='CO')

answered Jun 7, 2020 at 20:34

Sheldore

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1 Comment

PeterBe Over a year ago

Thanks Sheldore for your answer and help.

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