matplotlib changed rendering style unexpectedly in jupyter-notebook

Question

My matplotlib plots have changed styles unexpectedly. I am trying to pin down what I did to change them. My best guess is that I changed matplotlib versions, or I'm possibly am using a different backend.

A histogram plot currently looks like this:

They used to look like this (nice defined border lines between the bars):

I have made no changes to the code that generates the plots, but I have mucked with import statements, and re-installed various components of anaconda, including matplotlib for unrelated reasons.

Answer 1

Starting from matplotlib version 2.0, patches do not have edges anymore. See the Changes to the default style.

Options to set edges back on:

1. Use the edgecolor argument of the artist. E.g.

   plt.bar(...., edgecolor="k")
   

2. Use the rcParams to globally set edges,

   plt.rcParams['patch.force_edgecolor'] = True
   

   or edit you matplotlibrc file accordingly.

3. Turn the old style on again, using

   plt.style.use('classic')
   

Answer 2

Earlier this year, matplotlib changed their defaults. You want the edgecolor param.

plt.hist(np.random.norma(0,1,100), edgecolor='k')

You can use a classic style by passing plt.style.use('classic').