在 Python 中的列表列表中查找值是否存在

Question

I have a list of lists like this:

my_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

I now want to find if a value exists in my_list , and I need to do this in the most efficient way. I will use it in the following way:

if my_value in my_list:
    # do something

I have tried 2 versions as below.

# 1
if any(my_value in sublist for sublist in my_list)

# 2
for sublist in my_list:
    if my_value in sublist:
        return True

I find version 1 easier to read and doesn't require a separate function call. But does the any() function stop when it finds the value, or does it loop through the entire list? And is there a better, or more pythonic, way of doing this lookup?

Answer 1

The difference seems to be negligible with the second version only slightly faster.

my_list = [np.random.randint(1, 10000, 1000) for v in range(1000)]
my_value = np.random.randint(1, 10000, 1)[0]
def v1(my_list):
    if any(my_value in sublist for sublist in my_list):
        return True
    return False

def v2(my_list):
    for sublist in my_list:
        if my_value in sublist:
            return True
    return False

print(my_value)
%timeit v1(my_list)
%timeit v2(my_list)

>> 3012
>> 56.9 µs ± 3.1 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
>> 51.2 µs ± 383 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)