stacked chart combine with alluvial plot – python

Surprisingly little info out there regarding python and the pyalluvial package. I’m hoping to combine stacked bars and a corresponding alluvial in the same figure.

Using below, I have three unique groups, which is outlined in Group. I want to display the proportion of each Group for each unique Point. I have the data formatted this way as I need three separate stacked bar charts for each Point.

So overall (Ove) highlight the overall proportion taken from all three Points. Group 1 makes up 70%, Group 2 makes up 20%, Group 3 makes up 10%. But the proportion of each group changes at different intervals Points. I’m hoping to show this like a standard stacked bar chart, but add the alluvial over the top.

import pandas as pd
import pyalluvial.alluvial as alluvial 

df = pd.DataFrame({
    'Group': [1, 2, 3],
    'Ove': [0.7, 0.2, 0.1],
    'Point 1': [0.8, 0.1, 0.1],
    'Point 2': [0.6, 0.2, 0.2],
    'Point 3': [0.7, 0.3, 0.0],
    })

ax = alluvial.plot(
   df = df, 
   xaxis_names = ['Group','Point 1','Point 2', 'Point 3'], 
   y_name = 'Ove', 
   alluvium = 'Group',
)

Output shows the overall group proportion (1st bar) being correct. But the following stacked bars with the proportions.

If I transform the df and put the Points as a single column, then I don’t get 3 separate bars.

Answer

As correctly pointed out by @darthbaba, pyalluvial expects the dataframe format to consist of frequencies matching different variable-type combinations. To give you an example of a valid input, each Point in each Group has been labelled as present (1) or absent (0):

df = pd.DataFrame({
    'Group': [1] * 6 + [2] * 6 + [3] * 6,
    'Point 1': [1, 1, 1, 1, 0, 0] * 3,
    'Point 2': [0, 1, 0, 1, 1, 0] * 3,
    'Point 3': [0, 0, 1, 1, 1, 1] * 3,
    'freq': [23, 11, 5, 7, 10, 12, 17, 3, 6, 17, 19, 20, 28, 4, 13, 8, 14, 9]
    })

fig = alluvial.plot(df=df, xaxis_names=['Point 1','Point 2', 'Point 3'], y_name='freq', alluvium='Group', ignore_continuity=False)

Clearly, the above code doesn’t resolve the issue since pyalluvial has yet to support the inclusion of stacked bars, much like how it’s implemented in ggalluvial (see example #5). Therefore, unless you want to use ggalluvial, your best option IMO is to add the required functionality yourself. I’d start by modifying line #85.