matplotlib example capp treemaps (snippet)

Python matplotlib example 'capp treemaps'

Modules used in program:

• import platform
• import squarify
• import pandas as pd
• import matplotlib.pyplot as plt
• import matplotlib

python capp treemaps

Python matplotlib example: capp treemaps

#!/usr/bin/env python3
# coding: utf-8

import matplotlib
import matplotlib.pyplot as plt
import pandas as pd
import squarify
import platform

# print(versions)
print("python     : ", platform.python_version())
print("pandas     : ", pd.__version__)
print("matplotlib : ", matplotlib.__version__)
print("squarify   :  0.4.3")

# quantities plotted
# squarre area is the town surface area (superf)
# color scale is the town population in 2011 (p11_pop)

# read data from csv file
# data from CAPP opendata http://opendata.agglo-pau.fr/index.php/fiche?idQ=27
df = pd.read_csv("Evolution_et_structure_de_la_population/Evolution_structure_population.csv", sep=";")
df = df.set_index("libgeo")
df = df[["superf", "p11_pop"]]
df2 = df.sort_values(by="superf", ascending=False)

# treemap parameters
x = 0.
y = 0.
width = 100.
height = 100.
cmap = matplotlib.cm.viridis

# color scale on the population
# min and max values without Pau
mini, maxi = df2.drop("PAU").p11_pop.min(), df2.drop("PAU").p11_pop.max()
norm = matplotlib.colors.Normalize(vmin=mini, vmax=maxi)
colors = [cmap(norm(value)) for value in df2.p11_pop]
colors[1] = "#FBFCFE"

# labels for squares
labels = ["%s\n%d km2\n%d hab" % (label) for label in zip(df2.index, df2.superf, df2.p11_pop)]
labels[11] = "MAZERES-\nLEZONS\n%d km2\n%d hab" % (df2["superf"]["MAZERES-LEZONS"], df2["p11_pop"]["MAZERES-LEZONS"])

# make plot
fig = plt.figure(figsize=(12, 10))
fig.suptitle("Population et superficie des communes de la CAPP", fontsize=20)
ax = fig.add_subplot(111, aspect="equal")
ax = squarify.plot(df2.superf, color=colors, label=labels, ax=ax, alpha=.7)
# use this if you want to draw a border between rectangles
# you have to give both linewidth and edgecolor
# ax = squarify.plot(df2.superf, color=colors, label=labels, ax=ax, alpha=.7,
#                    bar_kwargs=dict(linewidth=1, edgecolor="#222222"))

ax.set_xticks([])
ax.set_yticks([])
ax.set_title("L'aire de chaque carré est proportionnelle à la superficie de la commune\n", fontsize=14)

# color bar
# create dummy invisible image with a color map
img = plt.imshow([df2.p11_pop], cmap=cmap)
img.set_visible(False)
fig.colorbar(img, orientation="vertical", shrink=.96)

fig.text(.76, .9, "Population", fontsize=14)
fig.text(.5, 0.1,
         "Superficie totale %d km2, Population de la CAPP : %d hab" % (df2.superf.sum(), df2.p11_pop.sum()),
         fontsize=14,
         ha="center")
fig.text(.5, 0.07,
         "Source : http://opendata.agglo-pau.fr/",
         fontsize=14,
         ha="center")

plt.savefig("capp_treemaps.png")
plt.show()

Python links

• Learn Python: https://pythonbasics.org/
• Python Tutorial: https://pythonprogramminglanguage.com