Converting For Loops To List Comprehensions

Question

I was trying to understand List Comprehensions because I needed to improve performance on my project.

I believe this is how they work but please correct me if I am wrong.

To convert a for loop into a list comprehension the below for loop -

for A in B:
 if Condition:
  List.append(A)

would turn into

E = [A for A in B if Condition]

I didn't realize this was a duplicate. If the answers on this post were unsatisfactory, you can see the other post at the top of this one.

Answer 1

I'm not sure if I understand what you asked correctly, but generally if you have a for loop like this :

some_list = []
for A in B:
    if condition:
        some_list.append(A)

It's equivalent list comprehension is :

some_list = [A for A in B if condition]

If you have an else for your condition, it would be a little different. Consider the following example :

some_list = []
for A in B:
    if condition:
        some_list.append(value1)
    else :
        some_list.append(value2)

It would become like this :

some_list = [value1 if condition else value2 for A in B]