Plot line in histogram python

I am drawing a histogram using matplotlib in python, and would like to draw a line representing the average of the dataset, overlaid on the histogram as a dotted line (or maybe some other color would do too). Any ideas on how to draw a line overlaid on the histogram?

I am using the plot() command, but not sure how to draw a vertical line (i.e. what value should I give for the y-axis?

thanks!

asked Apr 23, 2013 at 23:35

user308827user308827

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You can use plot or vlines to draw a vertical line, but to draw a vertical line from the bottom to the top of the y axis, axvline is the probably the simplest function to use. Here's an example:

In [80]: import numpy as np

In [81]: import matplotlib.pyplot as plt

In [82]: np.random.seed(6789)

In [83]: x = np.random.gamma(4, 0.5, 1000)

In [84]: result = plt.hist(x, bins=20, color='c', edgecolor='k', alpha=0.65)

In [85]: plt.axvline(x.mean(), color='k', linestyle='dashed', linewidth=1)
Out[85]: 

Result:

answered Apr 23, 2013 at 23:56

Warren WeckesserWarren Weckesser

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1

This is old topic and minor addition, but one thing I have often liked is to also plot mean value beside the line:

import numpy as np
import matplotlib.pyplot as plt
np.random.seed(6789)
x = np.random.gamma(4, 0.5, 1000)
result = plt.hist(x, bins=20, color='c', edgecolor='k', alpha=0.65)
plt.axvline(x.mean(), color='k', linestyle='dashed', linewidth=1)

min_ylim, max_ylim = plt.ylim()
plt.text(x.mean()*1.1, max_ylim*0.9, 'Mean: {:.2f}'.format(x.mean()))

Which produces following result:

rysqui

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answered Oct 24, 2018 at 4:41

I would look at the largest value in your data set (i.e. the histogram bin values) multiply that value by a number greater than 1 (say 1.5) and use that to define the y axis value. This way it will appear above your histogram regardless of the values within the histogram.

answered Apr 23, 2013 at 23:38

smitecsmitec

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1

Not the answer you're looking for? Browse other questions tagged python matplotlib axis or ask your own question.

To plot a line graph from histogram data in matplotlib, we use numpy histogram method to compute the histogram of a set of data.

Steps

• Add a subplot to the current figure, nrows=2, ncols=1 and index=1.

• Use numpy histogram method to get the histogram of a set of data.

• Plot the histogram using hist() method with edgecolor=black.

• At index 2, use the computed data (from numpy histogram). To plot them, we can use plot() method.

• To display the figure, use show() method.

Example

import numpy as np
from matplotlib import pyplot as plt
plt.rcParams["figure.figsize"] = [7.00, 3.50]
plt.rcParams["figure.autolayout"] = True
plt.subplot(211)
data = np.array(np.random.rand(100))
y, binEdges = np.histogram(data, bins=100)
plt.hist(data, bins=100, edgecolor='black')
plt.subplot(212)
bincenters = 0.5 * (binEdges[1:] + binEdges[:-1])
plt.plot(bincenters, y, '-', c='black')
plt.show()

Output

Updated on 11-May-2021 12:19:44

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