Bug summary

My aim is to plot a colormap with e.g. 5 discrete colors (with 5 ticks centered per color).

Under matplotlib 3.4.3, I got this working with the code snippet below using NoNorm; under 3.5.0, only one color is plotted.

Is this a bug - or is my setup incorrect/unidiomatic and worked only by chance before?

Code for reproduction

import matplotlib.pyplot as plt
from matplotlib import cm, colors

data = [1, 2, 3, 4, 5]

fig, ax = plt.subplots(figsize=(6, 1))
fig.subplots_adjust(bottom=0.5)

norm = colors.NoNorm(vmin=min(data), vmax=max(data))
cmap = cm.get_cmap("viridis", len(data))
cbar = fig.colorbar(cm.ScalarMappable(norm=norm, cmap=cmap), cax=ax, orientation="horizontal")
print(cbar.get_ticks())

Actual outcome

This is the output under matplotlib 3.5.0.

Expected outcome

This was the output under matplotlib 3.4.3.

Additional information

No response

Operating system

Ubuntu

Matplotlib Version

3.5.0

Matplotlib Backend

module://matplotlib_inline.backend_inline

Python version

Python 3.9.7

Jupyter version

3.2.4

Installation

conda