PYTHON ITERATORS

I
TERATORS
mytuple = ("apple", "banana", "cherry")
myit = iter(mytuple)
print(next(myit))

apple

print(next(myit))

banana

print(next(myit))

cherry

print(type(myit))

<class 'tuple_iterator'>

The for loop actually creates an iterator object and executes the next() method for each loop.
for x in mytuple:
  print(x)

apple
banana
cherry

mystr = "banana"
for x in mystr:
  print(x)

b
a
n
a
n
a

class MyNumbers:
  def __iter__(self):
    self.a = 1
    return self
  def __next__(self):
    x = self.a
    self.a += 1
    return x
myclass = MyNumbers()
myiter = iter(myclass)
print(next(myiter))

1

print(next(myiter))

2

print(next(myiter))

3

print(next(myiter))

4

print(next(myiter))

5

To prevent the iteration to go on forever, we can use the StopIteration statement.
class MyNumbers:
  def __iter__(self):
    self.a = 1
    return self
  def __next__(self):
    if self.a <= 20:
      x = self.a
      self.a += 1
      return x
     else:
      raise StopIteration
myclass = MyNumbers()
myiter = iter(myclass)
for x in myiter:
  print(x)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20