Reduce over DataFrames with the same index

reduce_df.py

import numpy.random as npr
import pandas as pd
from functools import reduce

def get_dfs():
    for i in range(10):
        yield pd.DataFrame(index=npr.permutation(10), data={f'c_{i}': npr.rand(10)})

def reducer(acc, x):
    merged = acc.merge(x, left_index=True, right_index=True, indicator=True, how='outer')
    assert 0 == merged[merged['_merge'] != 'both'].shape[0]
    return merged.drop('_merge', axis=1)

reduce(reducer, get_dfs())