2 Dimensional Arrays

A 2 dimensional (2D) array is like a grid or table with rows and columns. In Python, 2D arrays can be created using lists of lists. Each inner list represents a row.

Example of creating a 2D array with 3 rows and 3 columns:

array_2d = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

This creates a 3x3 grid where you can store and organize data in rows and columns.

To access elements in a 2D array, use two indices: the first for the row and the second for the column. Indexing starts at 0.

For example, to get the element in the 2nd row and 3rd column:

value = array_2d[1][2]

This retrieves the number 6 from the example array:

array_2d = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

Remember, the first index selects the row, and the second selects the column within that row.

To modify an element in a 2D array, you assign a new value to a specific position using its row and column indices.

For example, to change the element in the 1st row and 2nd column:

array_2d[0][1] = 10

This updates the value at that position.

Example:

array_2d = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

array_2d[0][1] = 10  # Changes 2 to 10

print(array_2d)
# Output:
# [[1, 10, 3],
#  [4, 5, 6],
#  [7, 8, 9]]

Modifying elements this way allows you to update data stored in the 2D array.

To process or examine all elements in a 2D array, you use loops to iterate through each row and each column within that row.

A common method is to use nested for loops: the outer loop goes through each row, and the inner loop goes through each element in that row.

array_2d = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

for row in array_2d:
    for element in row:
        print(element, end=' ')
    print()

This code prints each element in the 2D array in a grid format. Iterating like this helps you read, modify, or analyze all values systematically.