Source: 📖 Effective Python item 33

Use yield from when looping through a generator to create another generator

Instead of looping through a generator using for and manually yielding results, the yield from expression is faster and improves readability.

def my_gen(num):
	for i in range(num):
		yield i

def multiple_gen(multiple, num):
	for _ in range(multiple):
		for i in my_gen(num):
			yield i						# noisy, hard to follow
			
---

def multiple_gen(multiple, num):
	for _ in range(multiple):
		yield from my_gen(num)			# much clearer, and runs faster

This can be employed when using a sub-generator within an enclosing generator.

See also:

• Generator expressions explained
• Using generators