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 ?

First, array_length should be an integer and not a string:

array_length = len(array_dates)

Second, your for loop should be constructed using range:

for i in range(array_length):  # Use `xrange` for python 2.

Third, i will increment automatically, so delete the following line:

i += 1

---

Note, one could also just zip the two lists given that they have the same length:

import csv

dates = ['2020-01-01', '2020-01-02', '2020-01-03']
urls = ['www.abc.com', 'www.cnn.com', 'www.nbc.com']

csv_file_patch = '/path/to/filename.csv'

with open(csv_file_patch, 'w') as fout:
    csv_file = csv.writer(fout, delimiter=';', lineterminator='\n')
    result_array = zip(dates, urls)
    csv_file.writerows(result_array)

Follow up on Abdeali Chandanwala answer above (couldn't comment because rep<50) -

TL;DR: I was trying to iterate through a list of dictionaries incorrectly by focusing to iterate over the keys in the dictionary but instead had to iterate over the dictionaries themselves!

---

I came across the same error while having a structure like this:

{
   "Data":[
      {
         "RoomCode":"10",
         "Name":"Rohit",
         "Email":"[email protected]"
      },
      {
         "RoomCode":"20"
         "Name":"Karan",
         "Email":"[email protected]"
      }
   ]
}

And I was trying to append the names in a list like this-

Fixed it by-

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 I had to made sure that I only add dictionary objects to that list and list typed object into the list, this solved my issue as well.

In my case I was trying to change the value of a dict key but since my dict was there in a for loop and was getting changed to type list i was getting the same error.

for value in source_list:
    my_dict['my_key']=some_val
    dict=list(mydict)
    exctraction0 = dict[0]

i resolved it by making sure the type of dict remains the same by making a deepcopy and re-initializing after every iteration(that is what the use-case was all about).

copy_dict = copy.deepcopy(my_dict)
for value in source_list:
    my_dict =copy.deepcopy(copy_dict)
    my_dict['my_key']=some_val
    dict=list(mydict)
    exctraction0 = dict[0]

I received this error overloading a function in python where one function wrapped another:

def getsomething(build_datastruct_inputs : list[str]) -> int:
      # builds datastruct and calls getsomething
      return getsomething(buildit(build_datastruct_inputs))

def getsomething(datastruct : list[int]) -> int:
      # code
      # received this error on first use of 'datastruct'

Fix was to not overload and use unique method name.

def getsomething_build(build_datastruct_inputs : list[str]) -> int:
      # builds datastruct and calls getsomething
      return getsomething_ds(buildit(build_datastruct_inputs))

def getsomething_ds(datastruct : list[int]) -> int:
      # code
      # works fine again regardless of whether invoked directly/indirectly

Another fix could be to use python multipledispatch package which will let you overload and figures this out for you.

Was a bit confusing because where the error was occuring (nor message) corresponded to what cause was. I thought I had seen that python supported overloading natively but now I've learned it's implementation requires more work from the user.