CODEWITHSUNDEEP
pythonpandas
user1507844
user1507844

Reputation: 6563

Apply function on cumulative values of pandas series

Is there an equivalent of rolling_apply in pandas that applies function to the cumulative values of a series rather than the rolling values? I realize cumsum, cumprod, cummax, and cummin exist, but I'd like to apply a custom function.

Upvotes: 18

Views: 7522

Answers (2)

Harshit Agarwal
Harshit Agarwal

Reputation: 27

[Follow up to @Ffisegydd's answer]

Update for pandas == 1.0.5

df['example'] = df['data'].expanding().apply(sum_)

Upvotes: 1

Ffisegydd
Ffisegydd

Reputation: 53698

You can use pd.expanding_apply. Below is a simple example which only really does a cumulative sum, but you could write whatever function you wanted for it.

import pandas as pd

df = pd.DataFrame({'data':[10*i for i in range(0,10)]})

def sum_(x):
    return sum(x)


df['example'] = pd.expanding_apply(df['data'], sum_)

print(df)

#   data  example
#0     0        0
#1    10       10
#2    20       30
#3    30       60
#4    40      100
#5    50      150
#6    60      210
#7    70      280
#8    80      360
#9    90      450

Upvotes: 32

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