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matplotlibboxplotshapesoutliers

How to change outlier point symbol in Python matplotlib.pyplot

I am trying to change the usual Boxplot outlier shape (the jitter above the boxes) which is a circle by default to a diamond. I am using the following code so far:

import pandas as pd
import matplotlib.pyplot as plt

box = plt.boxplot([x1, x2], labels = ["Var1_Name",  
"Var2_Name"], notch=True, patch_artist=True)

Is there a way to make this change?

Solution

  • You can change the properties of the fliers via flierprops:

    import matplotlib.pyplot as plt
import numpy as np

box = plt.boxplot([np.random.randn(200), np.random.randn(200)], labels=["Var1_Name", "Var2_Name"],
                  notch=True, patch_artist=True,
                  flierprops={'marker': 'o', 'markersize': 10, 'markerfacecolor': 'fuchsia'})

    example plot

    To only change the symbol, you can leave out flierprops= and just use sym='*'. If, on the contrary, you need more control or need their exact positions, the fliers are also returned by box = plt.boxplot(...) as box['fliers'].