| Python: Iterators, Iteration, Iterator, Iterable

Computers are often used to automate repetitive tasks. Repeating identical or similar tasks without making errors is something that computers do well and people do poorly.

Iteration is a general term for taking each item of something, one after another. Any time you use a loop, explicit or implicit, to go over a group of items, that is iteration.

Loopings:

#looping over a list

for i in 'Big Data':

print(i)

#looping over characters

for i in range(0,3):

print(i)

#looping over a dictionary

for i in {'Y':1, 'o':2}:

print(i)

In Python, iterable and iterator have specific meanings.

An ITERABLE is:

-anything that can be looped over (i.e. you can loop over a string or file) or

-anything that can appear on the right-side of a for-loop: for x in iterable: ... or

-anything you can call with iter() that will return an ITERATOR: iter(obj) or

-an object that defines __iter__ that returns a fresh ITERATOR, or it may have a __getitem__ method -suitable for indexed lookup.

An ITERATOR is an object:

-with state that remembers where it is during iteration,

-with a __next__ method that:

-returns the next value in the iteration

-updates the state to point at the next value

-signals when it is done by raising StopIteration

-and that is self-iterable (meaning that it has an __iter__ method that returns self).

The best way to learn new things is to take a practical approach of the things you want to learn. Here is a fragment of code that demonstrates how to build a Iteration statement in Python:

ƒ python command

num = [1, 2, 5, 10]

abc = ['python', 'big data']

for i in num:

print(i)

for k in abc:

print(k)

√ output

5
10

python

big data