Custom Ticker

The matplotlib.ticker module defines many preset tickers, but was primarily designed for extensibility, i.e., to support user customized ticking.

In this example, a user defined function is used to format the ticks in millions of dollars on the y axis.

import matplotlib.pyplot as plt


def millions(x, pos):
    """The two arguments are the value and tick position."""
    return '${:1.1f}M'.format(x*1e-6)


fig, ax = plt.subplots()
# set_major_formatter internally creates a FuncFormatter from the callable.
ax.yaxis.set_major_formatter(millions)
money = [1.5e5, 2.5e6, 5.5e6, 2.0e7]
ax.bar(['Bill', 'Fred', 'Mary', 'Sue'], money)
plt.show()

References

The use of the following functions, methods, classes and modules is shown in this example:

• matplotlib.axis.Axis.set_major_formatter