Generators
A generator is a special routine that can
be used to control the iteration behavior of a loop.A generator is similar
to a function returning an array. A generator has parameters, it can be called
and it generates a sequence of numbers. But unlike functions, which return
a whole array, a generator yields one value at a time.
This requires less memory.
Generators in Python
- Are defined with the def keyword.
- Use the yield keyword.
- May use several yield keywords.
- Return an iterator.
This is an example of generators used in a python program
def gen():
x, y = 1, 2
yield x, y
x += 1
yield x, y
it = gen()
print it.next()
print it.next()
try:
print it.next()
except StopIteration:
print "Iteration finished"
Representing infinite sequences
Generators present us with some fun ways to manipulate infinite sequences
from __future__ import generators
def foo():
i = 0
while 1:
yield i
i = i
Recursive Generators
Generator functions can call themselves recursively.
from __future__ import generators
def abc():
a = deff()
for i in a:
yield i
yield 'abc'
def deff():
a = ijk()
for i in a:
yield i
yield 'deff'
def ijk():
for i in (1,2,3):
yield i
yield 'ijk'
