Multi-dimensional Arrays

In the previous section, we learned about arrays and their operations. Now, let's dive deeper into multi-dimensional arrays.

A multi-dimensional array is an array that contains other arrays. It can be visualized as a matrix with rows and columns. Each element in a multi-dimensional array is identified by its row index and column index.

Creating a 2D Array

To create a 2D array, you can define a list of lists. Each inner list represents a row in the 2D array. For example:

1# Creating a 2D array
2matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

In this example, matrix is a 2D array with 3 rows and 3 columns.

Accessing Elements

You can access elements in a 2D array by using the row and column indices. For example:

1# Accessing elements in a 2D array
2print(matrix[0][1])  # Output: 2

In this example, we access the element in the first row and second column.

Modifying Elements

Similar to accessing elements, you can modify elements in a 2D array by specifying the row and column indices. For example:

1# Modifying elements in a 2D array
2matrix[1][2] = 10
3print(matrix)  # Output: [[1, 2, 3], [4, 5, 10], [7, 8, 9]]

In this example, we modify the element in the second row and third column.

Finding the Length

To find the number of rows in a 2D array, you can use the len() function. To find the number of columns in a specific row, you can use the len() function on that row. For example:

1# Finding the length of a 2D array
2print(len(matrix))  # Output: 3
3print(len(matrix[0]))  # Output: 3

In this example, we find the length of matrix and the length of the first row.

Adding Elements

You can add a new row to a 2D array by using the append() method. The new row will be added at the end of the 2D array. For example:

1# Adding elements to a 2D array
2matrix.append([11, 12, 13])
3print(matrix)  # Output: [[1, 2, 3], [4, 5, 10], [7, 8, 9], [11, 12, 13]]

In this example, we add a new row with elements [11, 12, 13] to the matrix.

Removing Elements

To remove a row from a 2D array, you can use the pop() method and specify the index of the row to be removed. For example:

1# Removing elements from a 2D array
2matrix.pop(1)
3print(matrix)  # Output: [[1, 2, 3], [7, 8, 9], [11, 12, 13]]

In this example, we remove the second row from the matrix.

Multi-dimensional arrays are commonly used in image processing, robotics, and computer vision. They provide a way to represent and manipulate multi-dimensional data efficiently.

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# Creating a 2D array

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

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# Accessing elements in a 2D array

print(matrix[0][1])  # Output: 2

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# Modifying elements in a 2D array

matrix[1][2] = 10

print(matrix)  # Output: [[1, 2, 3], [4, 5, 10], [7, 8, 9]]

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# Finding the length of a 2D array

print(len(matrix))  # Output: 3

print(len(matrix[0]))  # Output: 3

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# Adding elements to a 2D array

matrix.append([11, 12, 13])

print(matrix)  # Output: [[1, 2, 3], [4, 5, 10], [7, 8, 9], [11, 12, 13]]

​

# Removing elements from a 2D array

matrix.pop(1)

print(matrix)  # Output: [[1, 2, 3], [7, 8, 9], [11, 12, 13]]