将嵌套的for循环转换为列表理解

Question

I made for loop code like this:

all = []
for sen_list in sen_lists:
    te = []
    for ele in sen_list:
        boolean = ele == "."
        te.append(boolean)
    all.append(te)

sen_lists = [['a', 'b', 'c', 'd', '.', '.'], ['e', 'f', 'g', 'h']]

upper code works well... but I want to convert list comprehension code.

I try like this:

[ele == "." for sen_list in rawdf.TEXT[:10] for ele in sen_list]

but this code is doesn't work.

please let me know. thanks.

Answer 1

Consider a nested list comprehension. Or, in other words, a list comprehension of list comprehensions.

The inner one represents your inner for loop. The outer one represents your outer for loop.

sen_lists = [['a', 'b', 'c', 'd', '.', '.'], ['e', 'f', 'g', 'h']]

res = [[ele == "." for ele in sen_list] for sen_list in sen_lists]

# [[False, False, False, False, True, True], [False, False, False, False]]

Answer 2

You need to wrap you boolean logic in [ ] so that boolean = knows what it is supposed to equal.

boolean = [ele == '.']

I don't know the logic to do it all on one line, like you're trying to do at the end of your question.. would be cool though.