Add source example files

source/plotting/charts/pie_chart.py

@@ -0,0 +1,24 @@
+"""
+Display sales of various cities in a sunburst chart.
+
+Given the cities can have recurring parents, we can have
+a sunburst chart with 2 rings, the centermost ring for the
+country, and the outmost ring to have sales per city.
+"""
+import matplotlib
+import pandas as pd
+from matplotlib import pyplot
+
+if __name__ == '__main__':
+    matplotlib.use("QtCairo")
+    df = pd.DataFrame(data={
+        "country": ["France", "France", "Spain", "Spain"],
+        "city": ["Montpellier", "Bordeaux", "Madrid", "Valencia"],
+        "sales": [150_000, 127_000, 97_200, 137_250]
+    })
+    df.set_index(["country", "city"], inplace=True)
+    total: int = df["sales"].sum()
+    print(df)
+    axes = df.plot.pie(subplots=True, autopct=lambda x: f"{x * total / 100:.0f} {x:.2f}%")
+    pyplot.show()
+