Pie chart on map¶

Let's draw pie chart on map.

Take as an example the results of the Montenegrin independence referendum in 2006. The dataset was downloaded from Wikipedia article "2006 Montenegrin independence referendum".

In [1]:

from lets_plot import *
from lets_plot.mapping import *

LetsPlot.setup_html() 

In [2]:

import pandas as pd

referendum_df = pd.read_csv("https://raw.githubusercontent.com/JetBrains/lets-plot-docs/master/data/montenegrin_referendum_2006.csv")
referendum_df.head()

Out[2]:

	Municipality	Yes	Yes%	No	No%	Registered	Voted	Voted%
0	Andrijevica	1084	27.60	2824	71.89	4369	3928	89.91
1	Bar	16640	63.07	9496	35.99	32255	26382	81.79
2	Berane	11268	46.85	12618	52.46	28342	24051	84.86
3	Bijelo Polje	19405	55.36	15437	44.04	40110	35051	87.39
4	Budva	5908	52.75	5180	46.25	12797	11200	87.52

Let's find geographical boundaries of these states using Lets-Plot geocoding module. And draw the percentage of those who voted "for" on the map by regions.

In [3]:

from lets_plot.geo_data import *

country = 'Montenegro'
municipalities = geocode_states(names=referendum_df['Municipality']).scope(country)

boundaries = municipalities.get_boundaries(resolution=15)

The geodata is provided by © OpenStreetMap contributors and is made available here under the Open Database License (ODbL).

In [4]:

boundaries = pd.merge(boundaries, referendum_df[['Municipality','Yes%']], left_on='state', right_on='Municipality')
boundaries.head()

Out[4]:

	state	found name	geometry	Municipality	Yes%
0	Andrijevica	Opština Andrijevica	MULTIPOLYGON (((19.61901 42.80456, 19.63347 42...	Andrijevica	27.60
1	Bar	Opština Bar	MULTIPOLYGON (((18.98948 42.16385, 18.98910 42...	Bar	63.07
2	Berane	Opština Berane	MULTIPOLYGON (((19.61729 42.88021, 19.62012 42...	Berane	46.85
3	Bijelo Polje	Opština Bijelo Polje	MULTIPOLYGON (((19.41061 43.07992, 19.41992 43...	Bijelo Polje	55.36
4	Budva	Opština Budva	MULTIPOLYGON (((18.80014 42.28039, 18.79997 42...	Budva	52.75

In [5]:

blank_theme = theme(line=element_blank(), axis=element_blank())

In [6]:

plot_title = ggtitle("Results of the Montenegrin independence referendum, 2006")

fill_colors = ['#a50026', '#d73027', '#66bd63', '#4daf4a','#006837']
    
map_layer = geom_map(aes(fill="Yes%"), 
                     data=boundaries,
                     tooltips=layer_tooltips()
                                 .title('@state')
                                 .line('\'Yes\' votes|@{Yes%}')
                                 .format('Yes%', '{} %')) + \
            scale_fill_gradientn(fill_colors)

ggplot() + map_layer + plot_title + blank_theme + ggsize(800, 700) 

Out[6]: