count elements = “” in tuples inside a list of lists

Question

I have a list of lists of tuples:

[[("AA","AA"),("QQ","")],[("CC",""),("QQ","")],...]

I am trying to count the number of empty values "" in the second value of the tuples. In the case above it would be:

I needed the answer in a list with the sum of occurrences for each nested list (in the example above it would be [1,2,...].

I was trying something like that

with open(file, 'r') as f:
    obj = pickle.load(f)
    count=Counter(elem for elem in el for el in obj if elem[0]=="")

Is it possible to somehow use 2 "for" for nested lists?

Answer 1

Use a list comprehension with sum() and a generator expression:

[sum(1 for t in tups if t[1] == '') for tups in obj]

Demo:

>>> obj = [[("AA", "AA"), ("QQ", "")], [("CC", ""), ("QQ", "")]]
>>> [sum(1 for t in tups if t[1] == '') for tups in obj]
[1, 2]

Answer 2

[sum(0 if x[1] else 1 for x in sub_lst) for sub_lst in big_list]