5 Best Ways to Check if Max Occurring Character of One String Appears Same Number of Times in Another in Python

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πŸ’‘ Problem Formulation: This article explores how to determine whether the most frequently occurring character in one string appears an equal number of times in another string, using Python. For example, in the string “apple,” the max occurring character ‘p’ appears twice. If we have another string, say “receipt,” we want to find out if ‘p’ also appears twice in this second string.

Method 1: Use Collections Counter

Python’s collections module provides a Counter class that can be used to count the occurrence of elements in an iterable. In this method, we create two Counter objects for both strings and then compare the count of the most frequent character from the first string with its count in the second string.

Here’s an example:

from collections import Counter

def check_max_char(s1, s2):
    counter1 = Counter(s1)
    counter2 = Counter(s2)
    max_char = max(counter1, key=counter1.get)
    return counter1[max_char] == counter2[max_char]

print(check_max_char("apple", "receipt"))

Output:

True

This code defines a function check_max_char() that takes two strings as input. It counts the occurrence of each character in both strings and then determines if the most frequent character from the first string has the same count in the second string. The output ‘True’ indicates that the character does indeed appear the same number of times.

Method 2: Using Dictionary Comprehension

This method leverages dictionary comprehension and the built-in max() function to find the maximum occurring character in the first string. It then compares its count with the second string’s count for the same character.

Here’s an example:

def check_max_char(s1, s2):
    count1 = {char: s1.count(char) for char in set(s1)}
    max_char = max(count1, key=count1.get)
    return count1[max_char] == s2.count(max_char)

print(check_max_char("balloon", "catalog"))

Output:

False

The function check_max_char() in this code creates a dictionary for the first string where each character is a key, and their respective counts as values. It then checks the max occurring character’s count against the second string using the count() method.

Method 3: Using Lambda and Map Functions

In this technique, we apply Python’s map() and lambda functions to map the count of each character from the first string to the second string and compare the maximum values.

Here’s an example:

def check_max_char(s1, s2):
    max_count = max(map(s1.count, s1))
    max_char = list(filter(lambda x: s1.count(x) == max_count, s1))[0]
    return s2.count(max_char) == max_count

print(check_max_char("programming", "gathering"))

Output:

False

The function check_max_char() employs map() to count the occurrences of characters in the first string, finds the maximum occurrence value, and filters out the character with this max value. It then compares the count of this max character in the second string.

Method 4: Without Using Extra Space

This method finds the maximum occurring character of the first string by iterating through it and maintaining a frequency count. It then checks the occurrence of that character in the second string.

Here’s an example:

def check_max_char(s1, s2):
    max_char, max_count = None, 0
    for char in set(s1):
        count = s1.count(char)
        if count > max_count:
            max_count, max_char = count, char
    return max_count == s2.count(max_char)

print(check_max_char("intuition", "tuition"))

Output:

True

The function check_max_char() determines the max occurring character by iterating through a set of unique characters in the first string. This approach doesn’t use any additional space for counters or dictionaries.

Bonus One-Liner Method 5: Using Max with Key Argument

This concise method finds the character with the max occurrence in the first string and compares its count to the occurrence in the second string, all in one line.

Here’s an example:

check_max_char = lambda s1, s2: s2.count(max(s1, key=s1.count)) == s1.count(max(s1, key=s1.count))
print(check_max_char("xylophone", "phenotype"))

Output:

True

The one-liner uses a lambda function to find the max occurring character in the first string and immediately checks its count in the second string.

Summary/Discussion

  • Method 1: Using Collections Counter. It’s very Pythonic and efficient for large strings. However, importing a module might be overkill for small tasks.
  • Method 2: Using Dictionary Comprehension. Clear and readable, but multiple count calls can be inefficient for longer strings.
  • Method 3: Using Lambda and Map Functions. Functional programming style, but may be less readable to those unfamiliar with these constructs.
  • Method 4: Without Using Extra Space. Space-efficient and doesn’t rely on additional data structures; however, it might be slower due to multiple count operations.
  • Method 5: One-Liner Using Max with Key Argument. Extremely concise, but not necessarily the most readable or efficient due to repeated count operations.