Creating Grouped bars in Matplotlib

Question

I have just started learning python and I am using the Titanic data set to practice

I am not able to create a grouped bar chart and it it giving me an error 'incompatible sizes: argument 'height' must be length 2 or scalar'

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

df = pd.read_csv("Titanic/train.csv")

top_five = df.head(5)
print(top_five)
column_no = df.columns
print(column_no)

female_count = len([p for p in df["Sex"] if p == 'female'])
male_count = len([i for i in df["Sex"] if i == 'male'])

have_survived= len([m for m in df["Survived"] if m == 1])
not_survived = len([n for n in df["Survived"] if n == 0])


plt.bar([0],female_count, color ='b')
plt.bar([1],male_count,color = 'y')
plt.xticks([0+0.2,1+0.2],['females','males'])
plt.show()

plt.bar([0],not_survived, color ='r')
plt.bar([1],have_survived, color ='g')
plt.xticks([0+0.2,1+0.2],['not_survived','have_survived'])
plt.show()

it works fine until here and I get two individual charts

Instead i want one chart that displays bars for male and female and color code the bars based on survival.

This does not seem to work

N = 2
index = np.arange(N)
bar_width = 0.35

plt.bar(index, have_survived, bar_width, color ='b')
plt.bar(index + bar_width, not_survived, bar_width,color ='r',)

plt.xticks([0+0.2,1+0.2],['females','males'])
plt.legend()

Thanks in advance!!

You can check [this](http://stackoverflow.com/a/20159305/2901002) and add some sample data to your question. — jezrael, Jul 15 '16 at 19:11
I am using train.csv from here https://www.kaggle.com/c/titanic/data — anaz8, Jul 15 '16 at 19:43

lanery · Accepted Answer · 2016-07-15T21:08:29.470

How about replacing your second block of code (the one that returns a ValueError) with this

bar_width = 0.35
tot_people_count = (female_count + male_count) * 1.0

plt.bar(0, female_count, bar_width, color ='b')
plt.bar(1, male_count, bar_width, color ='y',)

plt.bar(0, have_survived/tot_people_count*female_count, bar_width, color='r')
plt.bar(1, have_survived/tot_people_count*male_count, bar_width, color='g')

plt.xticks([0+0.2,1+0.2],['females','males'])

plt.legend(['female deceased', 'male deceased', 'female survivors', 'male survivors'],
           loc='best')

I get this bar graph as an output,

The reason for the error you get is that the left and height parameters of plt.bar must either have the same length as each other or one (or both) of them must be a scalar. That is why changing index in your code to the simple scalars 0 and 1 fixes the error.

Creating Grouped bars in Matplotlib

1 Answers1