计算元组列表中某个值的出现次数

Question

I have a list that looks like this :

fruit_list = [
    ['fruit1', ('banana',  '1234'), ('pear', '3456'), ('banana', '4578')],
    ['fruit2', ('apple',  '5474'), ('mango', '7854')],
    ['fruit3', ('Pineapple',  '4534'), ('apple', '5456'), ('apple', '4458')],
] 

What I would like to know is given a particular fruit and a particular list within that list, if that fruit appears more than once.

Something like fruit_list[0].count('banana') > 1 , but I don't think that will work because of the tuples.

Answer 1

You could use the sum() function with a generator expression to count matching tuples:

sum(t[0] == 'banana' for t in fruit_list[0]) > 1

This works because python booleans ( False and True ) are a subclass of int and False == 0 and True == 1 . Summing those gives you the count of matches:

>>> fruit_list = [
...     ['fruit1', ('banana',  '1234'), ('pear', '3456'), ('banana', '4578')],
...     ['fruit2', ('apple',  '5474'), ('mango', '7854')],
...     ['fruit3', ('Pineapple',  '4534'), ('apple', '5456'), ('apple', '4458')],
... ]
>>> sum(t[0] == 'banana' for t in fruit_list[0])
2
>>> sum(t[0] == 'banana' for t in fruit_list[0]) > 1
True