Force Axis Offset-Values to Whole Numbers or Specific Numbers in Matplotlib

Matplotlib allows you to plot data with axes that display offsets. However, sometimes it's desirable to have these offsets displayed as whole numbers or at a specific number.

Offset Display Issue

A common issue is that the offset on the y-axis, for instance, might display as "4.4 1e-8" when the actual value is "44 1e-9." Similarly, on the x-axis, an offset could be displayed as "5.54478e4" instead of the desired offset of "55447."

Solution

To force the offset to be displayed as a whole number or specific number, use the ScalarFormatter class from the matplotlib.ticker module. Here's the updated code:

from matplotlib.ticker import ScalarFormatter

# y-axis
y_formatter = ScalarFormatter(useOffset=False)
ax.yaxis.set_major_formatter(y_formatter)

# x-axis
x_formatter = ScalarFormatter(useOffset=False)
ax.xaxis.set_major_formatter(x_formatter)

By setting useOffset=False, the formatter disables the use of an offset in the axis label. This forces the axis to display the exact value of the tick mark.

Additional Notes

• The ScalarFormatter class can be further customized to control the formatting of the tick labels, such as setting the number of decimal places.
• The offset is not a separate object but rather a part of the tick label. When useOffset=True, the offset is appended to the tick label. When useOffset=False, the offset is not included in the tick label.