5 Best Ways to Write a Program in Python to Verify Camel Case Strings and Split Them

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πŸ’‘ Problem Formulation: In many programming scenarios, software developers are faced with the task of handling camel case strings. A camel case string, such as ‘VerifyCamelCaseString’, needs to be verified and then split into its constituent words, ‘Verify’, ‘Camel’, ‘Case’, and ‘String’. This article provides Python solutions for verifying if a string is camel case and, if it is, splitting it into a series where each word is an element.

Method 1: Using Regular Expressions

Regular expressions provide a powerful way to detect patterns in strings. For camel case strings, a regex can match uppercase letters indicating the start of a new word. The re library is used for this purpose in Python. The function includes verification of the camel case and then splitting where the uppercase letters occur, saving the result in a list.

Here’s an example:

import re

def split_camel_case(input_string):
    return re.findall(r'[A-Z](?:[a-z]+|[A-Z]*(?=[A-Z]|$))', input_string)

# Test the function
camel_case_string = "VerifyCamelCaseString"
split_words = split_camel_case(camel_case_string)
print(split_words)

Output:

['Verify', 'Camel', 'Case', 'String']

This code snippet uses the findall method from Python’s re module to search for all occurrences of a pattern defined to match uppercase letters followed by any number of lowercase letters. This pattern effectively splits the camel case string at the beginning of each new word.

Method 2: Using List Comprehension and isupper()

List comprehension in Python can be used along with the isupper() method to identify the indexes where a new word starts in a camel case string. By slicing the string using these indexes, we can create the series of words.

Here’s an example:

def split_camel_case(input_string):
    indexes = [i for i in range(1, len(input_string)) if input_string[i].isupper()]
    return [input_string[i:j] for i, j in zip([0] + indexes, indexes + [None])]

# Test the function
camel_case_string = "VerifyCamelCaseString"
split_words = split_camel_case(camel_case_string)
print(split_words)

Output:

['Verify', 'Camel', 'Case', 'String']

The code uses list comprehension to locate the indices of uppercase characters, indicating the start of a new word in the camel case string. Another list comprehension then slices the string from the start of each word to the beginning of the next word, effectively splitting the camel case string into a list of words.

Method 3: Iterating and Building Substrings

This method involves iterating over each character in the camel case string and building a new word each time an uppercase letter is encountered (after the first word). This straightforward approach builds the resulting list of words without the use of regular expressions or list comprehensions.

Here’s an example:

def split_camel_case(input_string):
    words = []
    current_word = ''
    for char in input_string:
        if char.isupper() and current_word:
            words.append(current_word)
            current_word = ''
        current_word += char
    words.append(current_word)
    return words

# Test the function
camel_case_string = "VerifyCamelCaseString"
split_words = split_camel_case(camel_case_string)
print(split_words)

Output:

['Verify', 'Camel', 'Case', 'String']

This snippet loops through each character, checks if it’s uppercase and if a current word has already begun. If so, it appends the current word to the result list and starts a new word. In the end, the current word is appended to ensure the last word is included in the results.

Method 4: Using itertools.groupby()

The itertools.groupby() function can group characters into words based on whether each character is uppercase or lowercase. Using a lambda function as the key, it can distinguish the start of each new word and split the camel case accordingly.

Here’s an example:

from itertools import groupby

def split_camel_case(input_string):
    word = ''.join([' ' + char if char.isupper() else char for char in input_string]).strip()
    return word.split()

# Test the function
camel_case_string = "VerifyCamelCaseString"
split_words = split_camel_case(camel_case_string)
print(split_words)

Output:

['Verify', 'Camel', 'Case', 'String']

The code prepends a space before each uppercase character to separate the words, then trims and splits the string by whitespaces. The result is the camel case string split into a list of words.

Bonus One-Liner Method 5: Using re.split()

A concise one-liner can achieve the camel case splitting by leveraging the re.split() function from the re module in Python. This elegant solution splits the string right before each uppercase letter in a single line of code.

Here’s an example:

import re

camel_case_string = "VerifyCamelCaseString"
split_words = re.split(r'(?=[A-Z])', camel_case_string)[1:]
print(split_words)

Output:

['Verify', 'Camel', 'Case', 'String']

This one-liner utilizes a regular expression pattern with a positive lookahead assertion that matches positions just before an uppercase letter, splitting the camel case string efficiently. It excludes the first element of the split result to avoid an empty string at the start.

Summary/Discussion

  • Method 1: Regular Expressions. Robust and compact. Requires understanding of regex. May not be as readable for beginners.
  • Method 2: List Comprehension and isupper(). Elegant and Pythonic. The splitting logic is less explicit, which might be harder for maintenance.
  • Method 3: Iterating and Building Substrings. Straightforward and easy to understand. Can be less efficient due to repeated string concatenation.
  • Method 4: Using itertools.groupby(). Utilizes standard library functions. Could be overkill for simple scenarios and a bit tricky to get right.
  • Bonus Method 5: Using re.split() One-Liner. Extremely concise. Requires a good grasp of regular expressions and Python slicing.