Python: tables with 2D lists

A game board, a seating plan and a class mark book are all tables: rows and columns. In Python you can store a table as a list of lists.

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A list of lists

Each item in the outer list is itself a list: one row.
scores = [[5, 8, 6],
          [9, 7, 10],
          [4, 6, 7]]
This is called a two-dimensional (2D) list. Other languages call it a 2D array.
scores as a table: scores[row][column]
Round 0Round 1Round 2
Player 0586
Player 19710
Player 2467

Row first, then column

To reach one item, give the row index, then the column index, both starting at 0.
scores = [[5, 8, 6],
          [9, 7, 10],
          [4, 6, 7]]
print(scores[1][2])
print(scores[0][1])
Output:
10
8
len(scores) gives the number of rows (3); len(scores[0]) gives the number of columns in row 0 (3).

Nested loops

A loop inside a loop visits every item, row by row.
scores = [[5, 8, 6],
          [9, 7, 10],
          [4, 6, 7]]
for row in scores:
    total = 0
    for s in row:
        total = total + s
    print(total)
Output:
19
26
17
These are the total scores for each player. You can also change an item: board[2][2] = "X".
Worked example

What does this print?
board = [["X", "O", "X"],
         [" ", "X", "O"],
         ["O", " ", " "]]
board[2][2] = "X"
print(board[2])

  1. board[2] is the third row: O, space, space.
  2. board[2][2] = "X" changes the last item in that row.
  3. Printing the row shows the whole list.

Answer: ['O', ' ', 'X']

Key idea

A 2D list is a list of lists that stores a table. Use name[row][column], with both indexes starting at 0. Nested loops visit every item.

Key words
AND
A Boolean operator that gives True (1) only when both inputs are True.
List
A data structure that stores many items under one name, in order, such as scores = [4, 7, 2].
Output
Information sent out from a computer, for example to a screen, speaker or printer.

All KS3 Computing key terms and definitions →

Quick check

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Extra practice

2 more questions

Try each one, then tap to check.

  1. grid is a 2D list with 5 rows, and each row has 6 items. How many items does it hold in total?

    Show the answer

    Answer: 30

    5 × 6 = 30.

  2. What is the FIRST number printed?
    scores = [[5, 8, 6],
    [9, 7, 10],
    [4, 6, 7]]
    for row in scores:
    total = 0
    for s in row:
    total = total + s
    print(total)

    Show the answer

    Answer: 19

    The first row totals 5 + 8 + 6 = 17.

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Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.

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