NumPy: Capitalize the first letter, lowercase, uppercase, swapcase, title-case of all the elements of a given array

Last update on April 29 2025 12:55:26 (UTC/GMT +8 hours)

3. String Case Transformations

Write a NumPy program to capitalize the first letter, lowercase, uppercase, swapcase, title-case of all the elements of a given array.

Sample Solution:-

Python Code:

# Importing the necessary library
import numpy as np

# Creating a NumPy array containing strings
x = np.array(['python', 'PHP', 'java', 'C++'], dtype=np.str)

# Displaying the original array
print("Original Array:")
print(x)

# Applying various string manipulation functions from np.char module
# Capitalizing the first character of each string
capitalized_case = np.char.capitalize(x)

# Converting all characters to lowercase
lowered_case = np.char.lower(x)

# Converting all characters to uppercase
uppered_case = np.char.upper(x)

# Swapping the case of characters (lowercase to uppercase and vice versa)
swapcased_case = np.char.swapcase(x)

# Capitalizing the first character of each word in the string
titlecased_case = np.char.title(x)

# Displaying the modified arrays after applying string manipulation functions
print("\nCapitalized: ", capitalized_case)
print("Lowered: ", lowered_case)
print("Uppered: ", uppered_case)
print("Swapcased: ", swapcased_case)
print("Titlecased: ", titlecased_case) 

Sample Input:

(['python', 'PHP', 'java', 'C++'], dtype=np.str)

Sample Output:

Original Array:
['python' 'PHP' 'java' 'C++']

Capitalized:  ['Python' 'Php' 'Java' 'C++']
Lowered:  ['python' 'php' 'java' 'c++']
Uppered:  ['PYTHON' 'PHP' 'JAVA' 'C++']
Swapcased:  ['PYTHON' 'php' 'JAVA' 'c++']
Titlecased:  ['Python' 'Php' 'Java' 'C++']

Explanation:

In the above exercise –

x1 = np.array(['python', 'PHP', 'java', 'C++'], dtype=np.str): This line creates a 1-dimensional numpy array x1 with 4 elements of string data type. The elements are 'python', 'PHP', 'Java', and 'C++'.

• np.char.capitalize(x) returns a copy of the input array x with the first character of each element capitalized.
• np.char.lower(x) returns a copy of the input array x with all characters in each element converted to lowercase.
• np.char.upper(x) returns a copy of the input array x with all characters in each element converted to uppercase.
• np.char.swapcase(x) returns a copy of the input array x with all uppercase characters converted to lowercase and vice versa.
• np.char.title(x) returns a copy of the input array x with the first character of each word in each element capitalized.

Pictorial Presentation:

For more Practice: Solve these Related Problems:

• Create a function that converts an array of strings to capitalized, lower, upper, swapcase, and title-case forms simultaneously.
• Apply different case transformations on an array and then concatenate the results into a single string per element.
• Implement a solution that conditionally applies uppercase if the string length is even, and lowercase if odd.
• Transform the array elements to title-case and then compare them with a manually formatted version for verification.

Go to:

• NumPy String Exercises Home ↩
• NumPy Exercises Home ↩

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