Matplotlib.ticker.FuncFormatter class in Python

import matplotlib.pyplot as plt
import matplotlib.ticker as tick
import numpy as np


x = np.linspace(0, 10, 1000)
y = 0.000001 * np.sin(10 * x)

fig = plt.figure()
ax = fig.add_subplot(111)

ax.plot(x, y)

def y_fmt(x, y):
    return '{:2.2e}'.format(x).replace('e', 'x10^')

ax.yaxis.set_major_formatter(tick.FuncFormatter(y_fmt))

plt.show()

import matplotlib.pyplot as plt
from matplotlib.ticker import FuncFormatter


fig, ax = plt.subplots()
ax.axis([0.01, 10000, 1, 1000000])
ax.loglog()

for axis in [ax.xaxis, ax.yaxis]:
    formatter = FuncFormatter(lambda y, _: '{:.16g}'.format(y))
    axis.set_major_formatter(formatter)

plt.show()