Divide each row of pandas DataFrame by the value in the main diagonal

Question

I have a dataframe called "cohort_any_action"

I want to create a percentage but when I try this code;

cohort_any_action.divide(cohort_any_action.iloc[:,0], axis=0)

I obtain this;

But I want the points where the same dates intersect to take the value 1, just as the cell where April 25 and April 25 intersect takes the value 1.

Asked By: bengisu yilmaz

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Source

Answer 1

Very close, you just need to obtain the values along the diagonal, not the first column as in your code. Here is one way to do that:

import numpy as np
import pandas as pd

# example data
df = pd.DataFrame(np.triu(np.random.rand(4,4)),columns=['a','b','c','d'])
df[df==0]=np.nan

      a     b     c     d
0  0.99  0.40  0.85  0.90
1   NaN  0.06  0.97  0.11
2   NaN   NaN  0.30  0.31
3   NaN   NaN   NaN  0.12

# divide by diagonal, row-wise
diagonal = df.to_numpy().diagonal()
df_norm = df.divide(diagonal, axis=0)

     a    b      c     d
0  1.0  0.4   0.86  0.91
1  NaN  1.0  16.17  1.83
2  NaN  NaN   1.00  1.03
3  NaN  NaN    NaN  1.00

Answered By: evces

Divide each row of pandas DataFrame by the value in the main diagonal

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