How to join two generators in Python?

Question

I want to change the following code

for directory, dirs, files in os.walk(directory_1):
    do_something()

for directory, dirs, files in os.walk(directory_2):
    do_something()

to this code:

for directory, dirs, files in os.walk(directory_1) + os.walk(directory_2):
    do_something()

I get the error:

unsupported operand type(s) for +: 'generator' and 'generator'

How to join two generators in Python?

Answer 1

itertools.chain() should do it.

It takes a list of iterables and yields from each one by one

def chain(*iterables):
    for it in iterables:
        for element in it:
            yield element

Usage example:

from itertools import chain
generator = chain('ABC', 'DEF')

for item in generator:
    print(item)

Output:

A
B
C
D
E
F