Python:NumPy .item()

The .item() method in Numpy copies an element of a NumPy array (ndarray) to a standard Python scalar (like int, float, bool) and returns it. The .item() method is handy for extracting a single value from an array, especially a 0-dimensional (scalar) array, into a native Python type.

Syntax

element = array.item(*args)

Parameters:

• array is an instance of ndarray.
• *args : int, optional
  • If no arguments are provided, the array must have only one element (i.e., array.size == 1), and that single element is returned.
  • If a single integer is provided, it is interpreted as a flat index into the array (like indexing array.ravel()[i]).
  • If a tuple of integers is provided, it is interpreted as a multi-dimensional index (e.g., arr.item((0, 1)) for a 2D array).

Return Value:

Returns a standard Python scalar (e.g., int, float, bool) corresponding to the selected element.

Example: Retrieving elements using item()

The following example shows how to extract elements using item():

import numpy as np

# 1D array
arr_1d = np.array([10, 20, 30])
element_1d = arr_1d.item(1) # Get element at index 1
print(f"Element from 1D array: {element_1d}, Type: {type(element_1d)}")

# 2D array
arr_2d = np.array([[1, 2], [3, 4]])
element_2d = arr_2d.item(0, 1) # Get element at row 0, column 1
print(f"Element from 2D array: {element_2d}, Type: {type(element_2d)}")

# 0D (scalar) array
arr_0d = np.array(99)
scalar_val = arr_0d.item() # No index needed for 0D array
print(f"Value from 0D array: {scalar_val}, Type: {type(scalar_val)}")

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Output of the above example:

Element from 1D array: 20, Type: <class 'int'>
Element from 2D array: 2, Type: <class 'int'>
Value from 0D array: 99, Type: <class 'int'>

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Codebyte Example

This example demonstrates the working of item(). It retrieves elements from different-shaped arrays using item():

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