How to plot histogram with x and y axis from dataframe in python

Question

I would like to plot histogram with pandas dataframe. I have four columns in my dataframe, but I would like to pick two of them and plot it. I plug in xaxis and yaxis values and draw three sub historgrams.

Here's how my code looks like:

fig = plt.figure(figsize=(9,7), dpi=100)

h = plt.hist(x=df_mean_h ['id'], y=df_mean_h ['mean'], 
color='red', label='h')

c = plt.hist(x=df_mean_c ['id'], y=df_mean_c ['mean'], 
color='blue', label='c')

o = plt.hist( x=df_mean_o['id'], y=df_mean_o ['mean'], 
color='green', label='o')

plt.show()

When I try to see the histogram, it displays nothing on the screen. How should I fix my code?

I can just guess: plt.show() ? Alternatively you could use DataFrame.plot.hist(by=None, bins=10, **kwds) see pandas.pydata.org/pandas-docs/stable/generated/… — Moritz
– Moritz, Commented Aug 15, 2017 at 16:49
I added plt.show() but it throws an error saying ValueError: setting an array element with a sequence. — ejshin1
– ejshin1, Commented Aug 15, 2017 at 17:40
your error probably stems from the fact that you do not pass an array to the plot but a pandas object. Check out the difference between df_mean_o['id'] and df_mean_o['id'].values — Moritz
– Moritz, Commented Aug 15, 2017 at 20:28

name goes here · Accepted Answer · 2017-08-15 18:00:07Z

1

You need to show the plot with plt.show()
plt.hist() works differently than scatter or a series. You can't send x= and y=

https://matplotlib.org/1.2.1/examples/pylab_examples/histogram_demo.html

To make your example work, just send plt.hist a single column to create the chart:

import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
d = {'one' : pd.Series([1., 2., 3.], index=['a', 'b', 'c']),
 'two' : pd.Series([1., 2., 3.], index=['a', 'b', 'c'])}
DF = pd.DataFrame(d)
fig = plt.figure(figsize=(9,7), dpi=100)

plt.hist(DF['two'])

plt.show()

answered Aug 15, 2017 at 18:00

name goes here

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2 Comments

ejshin1 Over a year ago

Thanks! Is there any way that I can show three histograms all together in one plot? I have to combine three histograms.

Moritz Over a year ago

you can make axis with fig, ax = plt.subplots(ncols=1) and then do ax.plot(...) or dataframe.plot.hist(..., ax=ax)

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