for loop iterator python code example
Example 1: python defining the iterator protocol
class RangeTen:
def __init__(self, *args): pass # optional
def __iter__(self):
'''Initialize the iterator.'''
self.count = -1
return self
def __next__(self):
'''Called for each iteration. Raise StopIteration when done.'''
if self.count < 9:
self.count += 1
return self.count
raise StopIteration
for x in RangeTen():
print(x) # 0, 1, ..., 9
Example 2: iterator in python
# define a list
my_list = [4, 7, 0, 3]
# get an iterator using iter()
my_iter = iter(my_list)
# iterate through it using next()
# Output: 4
print(next(my_iter))
# Output: 7
print(next(my_iter))
# next(obj) is same as obj.__next__()
# Output: 0
print(my_iter.__next__())
# Output: 3
print(my_iter.__next__())
# This will raise error, no items left
next(my_iter)
Example 3: python iterator
pies = ["cherry", "apple", "pumpkin", "pecan"]
iterator = iter(pies)
print(next(iterator))
#prints "cherry" because it's the current one being iterated over
Example 4: how to use iteration in python
n = 5
while n > 0:
print n
n = n-1
print 'Blastoff!'
Example 5: python for loop iterator
import numpy as np
# With array cycling
arr = np.array([1,2,3,4,5,6,7,8,9])
for i in range(len(arr)):
# logic with iterator use (current logic replaces even numbers with zero)
if arr[i] % 2 == 0: arr[i] = 0
print(arr)
# Output: [1, 0, 3, 0, 5, 0, 7, 0 , 9]