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         


        

Answer 1

2020 update: Work in both python 3 and python 2

import itertools

iterA = range(10,15)
iterB = range(15,20)
iterC = range(20,25)

### first option

for i in itertools.chain(iterA, iterB, iterC):
    print(i)

# 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

### alternative option, introduced in python 2.6

for i in itertools.chain.from_iterable( [iterA, iterB, iterC] ):
    print(i)

# 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

itertools.chain() is the basic.

itertools.chain.from_iterables is handy if you have an iterable of iterables. For example a list of files per subdirectory like [ ["src/server.py", "src/readme.txt"], ["test/test.py"] ].