swapcase() function - NumPy Last Updated : 27 Sep, 2025 Comments Improve Suggest changes Like Article Like Report The numpy.char.swapcase() function is used to convert uppercase characters to lowercase and lowercase characters to uppercase in each string element of a NumPy array. It works element-wise and returns a new array with the modified strings.For Example: This example demonstrates how np.char.swapcase() swaps the case of each character in a single string array. Python import numpy as np arr = np.array(['Hello World']) res = np.char.swapcase(arr) print(res) Output['hELLO wORLD'] Syntaxnumpy.char.swapcase(arr)Parameters: arr array_like -> Input array of strings.Return Value: ndarray -> New array with uppercase converted to lowercase and vice versa.ExamplesExample 1: In this example, we apply swapcase() on a string array containing alphanumeric values. Python import numpy as np arr = np.array(['P4Q R', '4q Rp', 'Q Rp4', 'rp4q']) res = np.char.swapcase(arr) print("Array:", arr) print("Result:", res) OutputArray: ['P4Q R' '4q Rp' 'Q Rp4' 'rp4q'] Result: ['p4q r' '4Q rP' 'q rP4' 'RP4Q'] Example 2: In this example, we use swapcase() on an array of words. Python import numpy as np arr = np.array(['Geeks', 'For', 'Geeks']) res = np.char.swapcase(arr) print("Array:", arr) print("Result:", res) OutputArray: ['Geeks' 'For' 'Geeks'] Result: ['gEEKS' 'fOR' 'gEEKS'] Example 3: Here, swapcase() is applied to sentences with mixed cases. Python import numpy as np arr = np.array(['NumPy Is Powerful', 'PYTHON is Fun']) res = np.char.swapcase(arr) print("Array:", arr) print("Result:", res) OutputArray: ['NumPy Is Powerful' 'PYTHON is Fun'] Result: ['nUMpY iS pOWERFUL' 'python IS fUN'] Create Quiz Comment J jana_sayantan Follow 0 Improve J jana_sayantan Follow 0 Improve Article Tags : Python Python-numpy Python numpy-String Operation Explore Python FundamentalsPython Introduction 2 min read Input and Output in Python 4 min read Python Variables 4 min read Python Operators 4 min read Python Keywords 2 min read Python Data Types 8 min read Conditional Statements in Python 3 min read Loops in Python - For, While and Nested Loops 5 min read Python Functions 5 min read Recursion in Python 4 min read Python Lambda Functions 5 min read Python Data StructuresPython String 5 min read Python Lists 4 min read Python Tuples 4 min read Python Dictionary 3 min read Python Sets 6 min read Python Arrays 7 min read List Comprehension in Python 4 min read Advanced PythonPython OOP Concepts 11 min read Python Exception Handling 5 min read File Handling in Python 4 min read Python Database Tutorial 4 min read Python MongoDB Tutorial 3 min read Python MySQL 9 min read Python Packages 10 min read Python Modules 3 min read Python DSA Libraries 15 min read List of Python GUI Library and Packages 3 min read Data Science with PythonNumPy Tutorial - Python Library 3 min read Pandas Tutorial 4 min read Matplotlib Tutorial 5 min read Python Seaborn Tutorial 3 min read StatsModel Library - Tutorial 3 min read Learning Model Building in Scikit-learn 6 min read TensorFlow Tutorial 2 min read PyTorch Tutorial 6 min read Web Development with PythonFlask Tutorial 8 min read Django Tutorial | Learn Django Framework 7 min read Django ORM - Inserting, Updating & Deleting Data 4 min read Templating With Jinja2 in Flask 6 min read Django Templates 5 min read Build a REST API using Flask - Python 3 min read Building a Simple API with Django REST Framework 3 min read Python PracticePython Quiz 1 min read Python Coding Practice 1 min read Python Interview Questions and Answers 15+ min read Like