how to concatenate list of lists into 1 list python code example

Example 1: python concatenate lists

a = [1, 2, 3]
b = [4, 5]

# method 1:
c = a + b # forms a new list with all elements
print(c) # [1, 2, 3, 4, 5]

# method 2:
a.extend(b) # adds the elements of b into list a
print(a) # [1, 2, 3, 4, 5]

Example 2: python merge list of lists

flat_list = [item for sublist in t for item in sublist]