[python] TypeError: list indices must be integers or slices, not str

I've got two lists that I want to merge into a single array and finally put it in a csv file. I'm a newbie with Python arrays and I don't understand how I can avoid this error :

def fill_csv(self, array_urls, array_dates, csv_file_path):
    result_array = []
    array_length = str(len(array_dates))

    # We fill the CSV file
    file = open(csv_file_path, "w")
    csv_file = csv.writer(file, delimiter=';', lineterminator='\n')

    # We merge the two arrays in one

    for i in array_length:
        result_array[i][0].append(array_urls[i])
        result_array[i][1].append(array_dates[i])
        i += 1

    csv_file.writerows(result_array)

And got :

  File "C:\Users\--\gcscan.py", line 63, in fill_csv
    result_array[i][0].append(array_urls[i])
TypeError: list indices must be integers or slices, not str

How can my count work ?

I had same error and the mistake was that I had added list and dictionary into the same list (object) and when I used to iterate over the list of dictionaries and use to hit a list (type) object then I used to get this error.

Its was a code error and made sure that I only added dictionary objects to that list and list typed object into the list, this solved my issue as well.