DOC: add gallery example

astromancer · astromancer · commit d50bf9a4a851 · 2024-06-17T14:12:14.000+02:00
diff --git a/galleries/examples/mplot3d/hexbin3d.py b/galleries/examples/mplot3d/hexbin3d.py
@@ -0,0 +1,37 @@
+"""
+========================================
+3D Histogram with hexagonal bins
+========================================
+
+Demonstrates visualising a 3D density map of data using hexagonal tessellation.
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+from matplotlib.cbook import hexbin
+
+# Fixing random state for reproducibility
+np.random.seed(42)
+
+# Generate samples from mltivariate Gaussian
+# Parameters
+mu = (0, 0)
+sigma = ([0.8, 0.3],
+         [0.3, 0.5])
+n = 10_000
+gridsize = 15
+# draw samples
+xy = np.random.multivariate_normal(mu, sigma, n)
+# histogram samples with hexbin
+xyz, (xmin, xmax), (ymin, ymax), (nx, ny) = hexbin(*xy.T, gridsize=gridsize,
+                                                   mincnt=3)
+# compute bar cross section size
+dxy = np.array([(xmax - xmin) / nx, (ymax - ymin) / ny / np.sqrt(3)]) * 0.95
+
+# plot
+fig, ax = plt.subplots(subplot_kw={'projection': '3d'})
+ax.hexbar3d(*xyz, dxy, cmap='plasma')
+ax.set(xlabel='x', ylabel='y', zlabel='z')
+
+plt.show()
