How to Find ndim of Array in NumPy: Simple Guide

To find the number of dimensions of a NumPy array, use the ndarray.ndim attribute. It returns an integer representing how many axes or dimensions the array has.

Syntax

The syntax to find the number of dimensions of a NumPy array is simple:

• array.ndim: Returns the number of dimensions (an integer).

Here, array is any NumPy array object.

python

import numpy as np

array = np.array([[1, 2], [3, 4]])
number_of_dimensions = array.ndim
print(number_of_dimensions)

Output

2

Example

This example shows how to create arrays with different dimensions and find their ndim values.

python

import numpy as np

# 1D array
array_1d = np.array([1, 2, 3])
print('1D array ndim:', array_1d.ndim)

# 2D array
array_2d = np.array([[1, 2, 3], [4, 5, 6]])
print('2D array ndim:', array_2d.ndim)

# 3D array
array_3d = np.array([[[1], [2]], [[3], [4]]])
print('3D array ndim:', array_3d.ndim)

Output

1D array ndim: 1
2D array ndim: 2
3D array ndim: 3

Common Pitfalls

Some common mistakes when checking the number of dimensions in NumPy arrays include:

• Trying to call ndim as a function like array.ndim() instead of accessing it as an attribute array.ndim.
• Confusing ndim with shape, which returns the size of each dimension, not the count of dimensions.

python

import numpy as np

array = np.array([1, 2, 3])

# Wrong: calling ndim as a function
try:
    print(array.ndim())
except TypeError as e:
    print('Error:', e)

# Right: access ndim as attribute
print('Correct ndim:', array.ndim)

Output

Error: 'int' object is not callable
Correct ndim: 1

Quick Reference

Property	Description	Example
ndim	Number of dimensions of the array	array.ndim
shape	Size of each dimension	array.shape
size	Total number of elements	array.size

Key Takeaways

Use the attribute array.ndim to get the number of dimensions of a NumPy array.

ndim returns an integer representing how many axes the array has.

Do not call ndim as a function; it is an attribute, not a method.

Remember that shape gives the size of each dimension, not the count of dimensions.

Arrays can have 1 or more dimensions, and ndim helps identify this quickly.