Example for plotting a bihistogram

i-jey · i-jey · commit 92a8f88c2d2a · 2023-10-24T10:10:47.000-07:00
diff --git a/galleries/examples/statistics/histogram_bihistogram.py b/galleries/examples/statistics/histogram_bihistogram.py
@@ -0,0 +1,40 @@
+"""
+==========
+Bihistogram
+==========
+
+How to plot a bihistogram with Matplotlib.
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+# Create a random number generator with a fixed seed for reproducibility
+rng = np.random.default_rng(19680801)
+
+# %%
+# Generate data and plot a bihistogram
+# -----------------------------------------
+#
+# To generate a bihistogram we need two datasets (each being a vector of numbers).
+# We will plot both histograms using plt.hist() and set the weights of the second one to be negative.
+# We'll generate data below and plot the bihistogram.
+
+N_points = 10_000
+n_bins = 30
+
+# Generate two normal distributions
+dataset1 = np.random.normal(0, 1, size=N_points)
+dataset2 = np.random.normal(1, 2, size=N_points)
+
+fig, ax = plt.subplots()
+
+# Plot the first histogram
+ax.hist(dataset1, bins=n_bins, label="Dataset 1")
+
+# Plot the second histogram (notice the negative weights, which flip the histogram upside down)
+ax.hist(dataset2, weights=-np.ones_like(dataset2), bins=n_bins, label="Dataset 2")
+ax.axhline(0, color="k")
+ax.legend()
+
+plt.show()
