Difference between a list comprehension and a for loop

Question

n=input()
y=n.split()
a=([int(x) for x in y])
print(a)

output

python .\\input_into_list.py
1 2 3
[1, 2, 3]

The above

Answer 1

The first example is what you call a list comprehension. It creates a list based on your values in a sequence and in this case your input y. List comprehensions are encouraged because of its simplicity and explicit purpose which returns you a list.

a = [int(x) for x in y]

Your second example is a for loop, loops, unlike the list comprehension, can be used for iterating through your sequence and perform multiple complex tasks. However, in your example variable a constantly gets updated with the latest value in y.

for i in y:
    print(i)
    a = [i]

To achieve the same result as a list comprehension:

a = []
for i in y:
    print(i)
    a.append(i)

To keep it short, if you are planning to return a list, do it with a list comprehension when possible. For Python as for any language, there is no hard-and-fast rule, so use your discretion with keeping efficiency and readability in mind.