How to create an array from the list of arrays in python
This post from stack overflow should give you what you want. The magic code boils down to the following.

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


You can also loop through the list of lists and merge them.

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

merged_list = []

for l in lists:
    merged_list += l

print(merged_list)
[1, 2, 3, 4, 5, 6, 7, 8, 9]