Example for assign Tuple result to two columns after .apply() in Pandas

pandas_apply_two_column_result.py

import pandas as pd
import random

def avg(a, b):
    return (a+b)/2

def diff(a, b):
    return abs(a-b)

def get_stats(a, b):
    return avg(a, b), diff(a, b)

rand_array = lambda i: [random.randint(0, 100) for i in range(0, i)]
df = pd.DataFrame({'i': range(0, 100),
                   'a': rand_array(100),
                   'b': rand_array(100)}).set_index('i')

df[['avg', 'diff']] = df.apply(lambda x: get_stats(x['a'],
                                                   x['b']),
                               axis=1,
                               result_type='expand')

df.to_csv('out.csv')