Drawing average line in histogram (matplotlib) Drawing average line in histogram (matplotlib) python python

Drawing average line in histogram (matplotlib)


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 npIn [81]: import matplotlib.pyplot as pltIn [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]: <matplotlib.lines.Line2D at 0x119758828>

Result:plot


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 npimport matplotlib.pyplot as pltnp.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:Average line with text


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.