Question

I have created a histogram with matplotlib using the pyplot.hist() function. I would like to add a Poison error square root of bin height (sqrt(binheight)) to the bars. How can I do this?

The return tuple of .hist() includes return[2] -> a list of 1 Patch objects. I could only find out that it is possible to add errors to bars created via pyplot.bar().

Answer 1

Indeed you need to use bar. You can use to output of hist and plot it as a bar:

import numpy as np
import pylab as plt

data       = np.array(np.random.rand(1000))
y,binEdges = np.histogram(data,bins=10)
bincenters = 0.5*(binEdges[1:]+binEdges[:-1])
menStd     = np.sqrt(y)
width      = 0.05
plt.bar(bincenters, y, width=width, color='r', yerr=menStd)
plt.show()