How to Count All Elements in a List of Lists in Python?

To count all elements in a list of lists in Python, you can use a nested loop to iterate through each element in each sublist and increment a counter for each element. Here is an example:

my_list = [[1, 2, 3], [4, 5], [6, 7, 8, 9]]
count = 0
for sublist in my_list:
    for element in sublist:
        count += 1

print(count)  # Output: 9

In this example, we first define a list of lists called my_list. We then initialize a counter variable called count to 0. We then use a nested loop to iterate through each sublist in my_list and each element in each sublist. For each element, we increment the count variable by 1. Finally, we print the value of count, which gives us the total number of elements in my_list.