recursion in generator

Question

Is there some special behaviors when using recursion in generator?

I can print 0,1,2,3,4 by following code:

def generator_recursion(n):
    if n < 0:
        return
    else:
        generator_recursion(n-1)
        print(n)
    
generator_recursion(4)

But when I change to generator like below code, It only print 4. I don't know why. please help.

def generator_recursion(n):
    if n < 0:
        return
    else:
        generator_recursion(n-1)
        yield n
    
gr = generator_recursion(4)
for k in gr:
   print(k)

Answer 1

You need to yield from the recursion.

def generator_recursion(n):
    if n < 0:
        return
    else:
        yield from generator_recursion(n-1)
        yield n
    
gr = generator_recursion(4)
for k in gr:
    print(k)

This prints:

0
1
2
3
4

​