Plotting distance arrows in technical drawing in Matplotlib

To plot distance arrows in technical drawing in matplotlib, we can use annotate() method with arrow properties.

Steps

Set the figure size and adjust the padding between and around the subplots.
Add a horizontal line across the axis using axhline() method, i.e., y=3.5.
Add a horizontal line across the axis using axhline() method, i.e., y=2.5.
Use annotate() method to draw an arrow line to show the distance and in the very next statement, use annotate() method again to display the distance between two horizontal lines.
To display the figure, use show() method.

Example

from matplotlib import pyplot as plt
plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True
plt.axhline(3.5)
plt.axhline(2.5)
plt.annotate(
   '', xy=(0.5, 3.5), xycoords='data',
   xytext=(0.5, 2.5), textcoords='data',
   arrowprops={'arrowstyle': '<->'})
plt.annotate(
   '$\it{d=1}$', xy=(0.501, 3.0), xycoords='data',
   xytext=(0.5, 3.5), textcoords='offset points')
plt.show()