Python 2D Array list indices must be integers or slices, not tuple

Question

I am trying to learn Python 2D arrays and I am trying to add to an empty one but am getting the error list indices must be integers or slices, not tuple

I wrote what I wanted to do in Java and am trying to translate it over to Python

My Java code:

Object[][] memoryArray = new Object[256][17];

        int memoryRow, memoryCol;
        int MBR = 12;
        int addr = MBR;
        memoryRow = addr / 16;
        memoryCol = addr % 16 + 1;
        memoryArray[memoryRow][memoryCol] = " "+Integer.toString(MBR);
        for (Object element: memoryArray) {
            System.out.println(element);
     }

My Python Code:

memArray = [[None], [None]]
MBR = 55
address = MBR 
memR = (address / 16)
memC = (address % 16 + 1)
memArray[[memR], [memC]] = " " + str(MBR)

If anyone could lead me to any pointers on how I should correctly implement this logic in Python? I am not sure what the error is trying to indicate.

I also was wondering if I would be better off using Numpy Arrays?

Does this answer your question? [How to define a two-dimensional array?](https://stackoverflow.com/questions/6667201/how-to-define-a-two-dimensional-array) — Amin Rashidbeigi, Nov 05 '20 at 21:05
Yes! I was confused by the range keyword. @QuangHoang also gave a excellent answer with one-line — HotWheels, Nov 05 '20 at 21:19

Quang Hoang · Accepted Answer · 2020-11-05T21:15:53.240

2

Java newbies here as well, but let's try translate together:

memArray = [[None], [None]]

is not a Python equivalence for

Object[][] memoryArray = new Object[256][17];

Instead:

memArray = [[None for _ in range(17)] for _ in range(256)]

And

# Java
memoryArray[memoryRow][memoryCol] = " "+Integer.toString(MBR);

translate directly to:

memArray[memR][memC] = " " + str(MBR)

And lastly, while Numpy array might help with advanced indexing over Python's list, if you are working with strings/objects, you wouldn't see much improvement in computing efficiency.

edited Nov 05 '20 at 21:15

answered Nov 05 '20 at 21:07

Quang Hoang

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Your suggestion for ```memArray = [[None for _ in 17] for _ in 256]``` gives me an error ```TypeError: 'int' object is not iterable``` – HotWheels Nov 05 '20 at 21:15
1

@HotWheels (Blushed icon) Sorry, sometimes I made that silly mistake. See updated answer. – Quang Hoang Nov 05 '20 at 21:16
this is a great answer, I did not realize the importance of the ```range``` keyword in Python. – HotWheels Nov 05 '20 at 21:20

score 0 · Answer 2 · answered Nov 05 '20 at 21:10

0

I think what you want is memArray[memR][memC] = " " + str(MBR) but the way it is it will not work because 1) you have to ensure memR is integer and 2) because your list is empty

answered Nov 05 '20 at 21:10

Flavio Moraes

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Isn't memR ensured as an integer because it takes an integer address/16 and stores it? I assume it does this because there are no type declarations in Python, at least to my knowledge. – HotWheels Nov 05 '20 at 21:16
in python 2 if address is integer, memR will be integer, but in python 3 it will be a float unless you use int(address / 16) – Flavio Moraes Nov 05 '20 at 22:32

Python 2D Array list indices must be integers or slices, not tuple

2 Answers2