A look at itertools chain method

The python itertools module is a collection of tools for handling iterators. I want to make an honest effort to break the habit of repetitive standard patterns of basic python functionality. For example…

We have a list of tuples.

a = [(1, 2, 3), (4, 5, 6)]
a = [(1, 2, 3), (4, 5, 6)]
a = [(1, 2, 3), (4, 5, 6)]

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In order to iterate over the list and the tuples, we have a nested for loop.

for x in a:
  for y in x:
    print(y)
 # output 
1
2
3
4
5
6
for x in a:
  for y in x:
    print(y)

 # output 

1
2
3
4
5
6
for x in a:
  for y in x:
    print(y)

 # output 

1
2
3
4
5
6

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I have decided to challenge myself to start using all that itertools has to offer in my every day solutions. Today lets take a look at the chain method!

This first approach will only return the two tuples as as index 0 and 1. Instead of nesting another loop, lets apply the chain method.

from itertools import chain
a = [(1, 2, 3), (4, 5, 6)]
for _ in chain(a, b):
  print(_)
 # output 
 (1, 2, 3)
 (4, 5, 6)
from itertools import chain

a = [(1, 2, 3), (4, 5, 6)]

for _ in chain(a, b):
  print(_)

 # output 
 (1, 2, 3)
 (4, 5, 6)
from itertools import chain

a = [(1, 2, 3), (4, 5, 6)]

for _ in chain(a, b):
  print(_)

 # output 
 (1, 2, 3)
 (4, 5, 6)

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now we have access to iterate over the tuples without nesting another iteration with a for loop.

for _ in chain.from_iterable(a):
  print(_)
# output
1
2
3
4
5
6
for _ in chain.from_iterable(a):
  print(_)

# output

1
2
3
4
5
6
for _ in chain.from_iterable(a):
  print(_)

# output

1
2
3
4
5
6

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I think the chain method gives the flexibility to use this as a default choice for list iteration.

原文链接：A look at itertools chain method