I have a list assigned to the variable my_list.
my_list = [[(1, 2)], [(4, 8), (2, 3)], [(1, 6), (6,7), (8,9)]].
I need to find the length of my_list, but len(my_list) only returns 3.
I want it to return 6. I am new to python. Is there any Python function that will return the full length of my_list including the nested lists?
There's no built in function like that, but you can get it easily with a generator expression:
length = sum(len(inner_list) for inner_list in my_list)
You can use itertools.chain.from_iterable.
my_list = [[(1, 2)], [(4, 8), (2, 3)], [(1, 6), (6,7), (8,9)]]
length = len(list(itertools.chain.from_iterable(my_list)))
print(length)
# >>> 6
Edit: If you have to do this a lot, and don't want to type len(list(itertools.chain.... each time, you can create your own function.
def my_len(arr):
return len(list(itertools.chain.from_iterable(arr)))
Then call my_len on any list of lists you need the length of.
my_list = [[(1, 2)], [(4, 8), (2, 3)], [(1, 6), (6,7), (8,9)]]
print(my_len(my_list))
# > 6
Flatten the list:
my_list = [[(1, 2)], [(4, 8), (2, 3)], [(1, 6), (6,7), (8,9)]];
flat = [item for sublist in my_list for item in sublist];
print (len(flat));
this should work:
sum(len(x) for x in mylist)
basically its doing a little
loop over the elements of "mylist". len(mylist) gives 3 because obviously there are 3 elements in this "outer" list
. The lists nested inside each have their own number of elements, the sum function is just an easy way to run a counter over these elements.
sorry for my very blasphemous explanation, I am not a by programmer by training.
edit: i see someone has already posted this above
