列表理解以修改列表

Question

I'm trying to modify values in a list of list via list comprehension. I'm stuck on how to implement this though when creating the inner list (please see modify_word(j) line below).

#loop through each tweet
for i in all_data: 
    #loop through each word of each tweet
    for j in i: 
        #find the values we're interested in
        if j not in set(all_cities) and meets_criteria(j):
            #here is where I want to make a list of the modified word for each iteration of i (tweet)
            modify_word(j)

I failed miserably with this:

 new_data = [[modify_word(j) if (meets_criteria(j) and j not in set(all_cities)) for j in i] for i in all_data]

Anyone have an idea on how I might be able to do this? Thanks as always.

Answer 1

Why do you want to convert in the first place?

If there is a need then this should work

[j for i in all_data for j in i if j not in set(all_cities) and meets_criteria(j)]

The best way to remember this is that the order of for loop inside the list comprehension is based on the order in which they appear in traditional loop approach. Outer most loop comes first, and then the inner loops subsequently.