How to pass a Python pandas function as a variable/parameter in another function?

Question

import pandas as pd

def func_sum(df, cols, col):
    res = df[cols].groupby(col).sum()
    return res

def func_count(df, cols,col):
    res = df[cols].groupby(col).count()
    return res

def func_ave(df, cols, col):
    res = df[cols].groupby(col).mean()
    return res

The way I did to combine these three functions is like below, which is not very elegant.

def func(df, cols, col, method):
    if method == 'sum':
        return df[cols].groupby(col).sum()
    if method == 'count':
        return df[cols].groupby(col).count()
    if method == 'mean':
        return df[cols].groupby(col).mean()

I wonder if there is a better way to do this without using IF ELSE statement. How Can I Pass the function of (sum, count, or mean) as a variable and then let's the passed function variable to be called inside the main 'func' function.

I would greatly appreciate any suggestions.

Possible duplicate of Calling a function of a module by using its name (a string) — End genocide - save Gaza
– End genocide - save Gaza, Commented Apr 25, 2019 at 13:25

0x5453 · Accepted Answer · 2019-04-25 13:26:41Z

1

Use groupby.agg, which takes one or more functions by reference or by name.

For example:

def func(df, cols, col, method):
    return df[cols].groupby(col).agg(method)

func(df, cols, col, pd.Series.sum)
func(df, cols, col, 'count')
func(df, cols, col, np.mean)

answered Apr 25, 2019 at 13:26

0x5453

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1 Comment

Elsa Li Over a year ago

It is good to learn about pandas' agg function. Thanks a lot!

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