3.9 Venn Chart

A Venn diagram is an illustration that uses circles to show the relationships among things or finite groups of things. Venn diagrams help to visually represent the similarities and differences between the two concepts.

We can usematplotlib-vennthe library to draw a Venn chart. It contains four main functions: venn2, venn2_circles, venn3 and venn3_circles.

1. Installation

pip install matplotlib-venn

2. 2-Group Venn Chart

There are two ways to draw a Venn Chart. One is to give directly the size of your group and their intersection. The other is to give 2 sets of values, python will calculate itself the length of each set (each group) and the number of common values (their intersection).

The functions venn2 and venn2_circles accept as their only required argument a 3-element list (Ab, aB, AB) of subset sizes

# import library to draw a  2-group Venn chart
from matplotlib_venn import venn2

Option 1

plt.figure(figsize = (6,6))
venn2(subsets = (3, 2, 1),set_labels = ('Group A', 'Group B'))
plt.show()

Option 2

plt.figure(figsize = (6,6))
venn2([set(['A', 'B', 'C', 'D']), set(['D', 'E', 'F'])])
plt.show()

3. 3-Group Venn Chart

Similarly, the functions venn3 and venn3_circles take a 7-element list of subset sizes (Abc, aBc, ABc, abC, AbC, aBC, ABC)

from matplotlib_venn import venn3, venn3_circles

#  make a basic 3 groups Venn chart

plt.figure(figsize = (8,8))
plt.title("Three Groups Venn diagram")

v=venn3(subsets = (10, 6, 20, 7,9,1,3), 
        set_labels = ('Group A', 'Group B', 'Group C'))

# add some customization
c=venn3_circles(subsets = (10, 6, 20, 7,9,1,3), 
                linestyle='dashed', linewidth=3, color="darkblue")