NumPy ndarray.item() Method

NumPy ndarray.item()

The numpy.ndarray.item() method is used to extract a scalar value from an array. It allows retrieving a single element by specifying its index. This method is useful when working with small arrays and needing direct access to a single element.

Syntax

ndarray.item(*args)

Parameters

Parameter	Type	Description
*args	int or tuple of ints, optional	Specifies the index of the element to be retrieved. It can be a single integer (for 1D arrays) or a tuple of integers (for multi-dimensional arrays).

Return Value

Returns a scalar value that corresponds to the specified index in the array.

---

Examples

1. Extracting an Element from a 1D Array

In this example, we create a one-dimensional NumPy array and extract an element using the item() method.

import numpy as np

# Creating a 1D NumPy array
arr = np.array([10, 20, 30, 40, 50])

# Extracting an element at index 2 (third element)
result = arr.item(2)
print(result)  # Output: 30

Output:

30

The element at index 2 (third position) is extracted, which is 30.

2. Extracting an Element from a 2D Array

Here, we extract an element from a two-dimensional array using a tuple index.

import numpy as np

# Creating a 2D NumPy array
arr = np.array([[1, 2, 3],
                [4, 5, 6]])

# Extracting an element at row index 1, column index 2
result = arr.item((1, 2))
print(result)  # Output: 6

Output:

6

The element at row index 1 and column index 2 is extracted, which is 6.

3. Extracting the First and Last Elements from an Array

We demonstrate how to retrieve the first and last elements from a 1D array.

import numpy as np

# Creating a NumPy array
arr = np.array([5, 15, 25, 35, 45])

# Extracting the first element (index 0)
first_element = arr.item(0)

# Extracting the last element (index -1)
last_element = arr.item(-1)

print(first_element)  # Output: 5
print(last_element)   # Output: 45

Output:

5
45

Using index 0 retrieves the first element, and index -1 retrieves the last element of the array.

4. Using item() on a Multi-Dimensional Array

We extract an element from a 3D array using a tuple of indices.

import numpy as np

# Creating a 3D NumPy array
arr = np.array([[[10, 20], [30, 40]],
                [[50, 60], [70, 80]]])

# Extracting the element at depth index 1, row index 0, column index 1
result = arr.item((1, 0, 1))
print(result)  # Output: 60

Output:

60

The element at depth index 1, row index 0, and column index 1 is retrieved, which is 60.