Python Numpy - Get Array Shape or Dimensions

NumPy - Array Shape or Dimensions

To get the shape or dimensions of a NumPy Array, use ndarray.shape, where ndarray is the name of the NumPy array you are interested in. The ndarray.shape property returns a tuple with the size of the array along each axis.

Examples

1. Get shape of multi-dimensional NumPy array

In the following example, we initialize a multi-dimensional numpy array. We will use the ndarray.shape property to get the shape of the array programmatically.

Python Program

import numpy as np

#initialize an array
arr = np.array([[[11, 11, 9, 9],
                  [11, 0, 2, 0]],
                 [[10, 14, 9, 14],
                  [0, 1, 11, 11]]])
# get array shape
shape = arr.shape
print(shape)

Explanation:

  1. The array is a 3D array with two 2x4 matrices.
  2. The arr.shape returns a tuple of the form (2, 2, 4), representing the dimensions of the array: 2 matrices, 2 rows per matrix, and 4 columns per row.

Output

(2, 2, 4)

2. Get shape of 2D NumPy array

In the following example, we create a 2D numpy array with 2 rows and 4 columns. We will then use ndarray.shape to get the shape.

Python Program

import numpy as np

#initialize an array
arr = np.array([[11, 11, 9, 9],
                  [11, 0, 2, 0]])
# get array shape
shape = arr.shape
print(shape)

Explanation:

  1. The array has 2 rows and 4 columns.
  2. The shape will be represented as a tuple (2, 4).

Output

(2, 4)

3. Get shape of 1-Dimensional NumPy array

In this example, we take a one-dimensional numpy array with 4 elements and find its shape using ndarray.shape.

Python Program

import numpy as np

#initialize an array
arr = np.array([11, 11, 9, 9])
# get array shape
shape = arr.shape
print(shape)

Explanation:

  1. The array has 4 elements, so its shape will be (4,), indicating it's a 1D array with 4 elements.

Output

(4,)

4. Get shape of higher-dimensional NumPy array

In this example, we create a 4D numpy array. Let's see how the shape of such an array looks when analyzed.

Python Program

import numpy as np

#initialize a 4D array
arr = np.array([[[[11, 12, 13], [14, 15, 16]], [[17, 18, 19], [20, 21, 22]]],
                 [[[23, 24, 25], [26, 27, 28]], [[29, 30, 31], [32, 33, 34]]]])
# get array shape
shape = arr.shape
print(shape)

Explanation:

  1. This array is 4-dimensional with the shape (2, 2, 2, 3):
  2. 2 blocks (depth), each containing 2 matrices, each of size 2x3 (2 rows and 3 columns).

Output

(2, 2, 2, 3)

Summary

In this Numpy Tutorial, we learned how to get the shape of a given numpy array using the ndarray.shape property. This method works for arrays of any dimension, whether 1D, 2D, or higher-dimensional arrays. We covered several examples to demonstrate the use of this function across different array types.

Python Libraries