Error bar rendering on polar axis#

Demo of error bar plot in polar coordinates. Theta error bars are curved lines ended with caps oriented towards the center. Radius error bars are straight lines oriented towards center with perpendicular caps.

import numpy as np
import matplotlib.pyplot as plt

theta = np.arange(0, 2 * np.pi, np.pi / 4)
r = theta / np.pi / 2 + 0.5

fig = plt.figure(figsize=(10, 10))
ax = fig.add_subplot(projection='polar')
ax.errorbar(theta, r, xerr=0.25, yerr=0.1, capsize=7, fmt="o", c="seagreen")
ax.set_title("Pretty polar error bars")
plt.show()
Pretty polar error bars

Please acknowledge that large theta error bars will be overlapping. This may reduce readability of the output plot. See example figure below:

fig = plt.figure(figsize=(10, 10))
ax = fig.add_subplot(projection='polar')
ax.errorbar(theta, r, xerr=5.25, yerr=0.1, capsize=7, fmt="o", c="darkred")
ax.set_title("Overlapping theta error bars")
plt.show()
Overlapping theta error bars

On the other hand, large radius error bars will never overlap, they just lead to unwanted scale in the data, reducing the displayed range.

fig = plt.figure(figsize=(10, 10))
ax = fig.add_subplot(projection='polar')
ax.errorbar(theta, r, xerr=0.25, yerr=10.1, capsize=7, fmt="o", c="orangered")
ax.set_title("Large radius error bars")
plt.show()
Large radius error bars

References

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

Total running time of the script: ( 0 minutes 4.966 seconds)

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