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List comprehension is an elegant way to define and create lists based on existing lists. List comprehension is generally more compact and faster than normal functions and loops for creating list. However, we should avoid writing very long list comprehensions in one line to ensure that code is user-friendly.
List comprehensions provide us with a simple way to create a list based on some sequence or another list that we can loop over. In python terminology, anything that we can loop over is called iterable. At its most basic level, list comprehension is a syntactic construct for creating lists from existing lists.
Some of the benefits are as follows: List Comprehensions are easy to understand and make code elegant. We can write the program with simple expressions. List comprehensions are way faster than for loop and other methods like a map.
Because of differences in how Python implements for loops and list comprehension, list comprehensions are almost always faster than for loops when performing operations.
Normally, list comprehensions are used to derive a new list from an existing list. Eg:
>>> a = [1, 2, 3, 4, 5]
>>> [i for i in a if i > 2]
[3, 4, 5]
Should we use them to perform other procedures? Eg:
>>> a = [1, 2, 3, 4, 5]
>>> b = []
>>> [b.append(i) for i in a]
[None, None, None, None, None]
>>> print b
[1, 2, 3, 4, 5]
or should I avoid the above and use the following instead?:
for i in a:
b.append(i)
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