Find the most frequent character in a String in Python

# Table of Contents

1. Find the most frequent character in a String in Python
2. Find the most frequent character in a String using max()
3. Find the most frequent character in a String using statistics.mode()

# Find the most frequent character in a String in Python

To find the most frequent character in a string:

1. Use the collections.Counter() class to create a counter object.
2. Use the most_common() method to get the most frequent character in the string.

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from collections import Counter

string = 'aaabbc'


counter = Counter(string)

# ✅ Find the most frequent character in a string
most_frequent = counter.most_common(1)[0]
print(most_frequent)  # 👉️ ('a', 3)

print(most_frequent[0])  # 👉️ 'a'

# ✅ Find the N most frequent characters in a string

most_frequent_2 = counter.most_common(2)
print(most_frequent_2)  # 👉️ [('a', 3), ('b', 2)]

We used the collections.Counter class to count the occurrences of each character.

The Counter class from the collections module is a subclass of the dict class.

The class is basically a mapping of key-count pairs.

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from collections import Counter

string = 'aaabbc'


counter = Counter(string)
print(counter)  # 👉️ Counter({'a': 3, 'b': 2, 'c': 1})

Counter objects implement a most_common() method that returns a list of the N most common elements and their counts from the most common to the least.

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from collections import Counter

string = 'aaabbc'


counter = Counter(string)
print(counter)  # 👉️ Counter({'a': 3, 'b': 2, 'c': 1})

most_frequent = counter.most_common(1)[0]
print(most_frequent)  # 👉️ ('a', 3)

print(most_frequent[0])  # 👉️ 'a'

Python indexes are zero-based, so the first item in a list has an index of 0, and the last item has an index of -1 or len(my_list) - 1.

If no argument is provided to the most_common method, it lists all character counts.

You can also use this approach to get the most common N characters in a string.

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from collections import Counter

string = 'aaabbc'


counter = Counter(string)
print(counter)  # 👉️ Counter({'a': 3, 'b': 2, 'c': 1})

most_frequent_2 = counter.most_common(2)
print(most_frequent_2)  # 👉️ [('a', 3), ('b', 2)]

We passed 2 as an argument to the most_common() method, so it returned the most common 2 characters in the string.

Alternatively, you can use the max() function.

# Find the most frequent character in a String using max()

This is a four-step process:

1. Use the max() function.
2. Pass the key argument to the functions.
3. Use the str.count() method to count the occurrences of each character.
4. The max() function will return the most common character.

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string = 'aaabbc'

most_common = max(set(string), key=string.count)

print(most_common)  # 👉️ 'a'

We used the max() function to get the most common character in a string.

The max() function returns the largest item in an iterable or the largest of two or more arguments.

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my_list = [15, 45, 30]

result = max(my_list)

print(result)  # 👉️ 45

The max function also takes an optional key argument.

We used the set() class to convert the string to a set object to remove any duplicates.

You can imagine that:

1. The str.count() method gets called with each element in the set.
2. The method returns the number of times the character appears in the string.
3. The max() function returns the most common character.

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string = 'aaabbc'

most_common = max(set(string), key=string.count)

print(most_common)  # 👉️ 'a'

The str.count method returns the number of occurrences of a substring in a string.

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print('bobby'.count('b'))  # 👉️ 3
print('bobby'.count('x'))  # 👉️ 0

# Find the most frequent character in a String using statistics.mode()

Alternatively, you can use the statistics.mode() method.

The mode() method returns the single most common value in the provided iterable.

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from statistics import mode

string = 'aaabbc'

most_common = mode(string)

print(most_common)  # 👉️ 'a'

The statistics.mode() method takes an iterable and returns the most common value in the iterable.

If there are multiple values with the same frequency, the method returns the first encountered value.

If the provided iterable is empty, the method raises a StatisticsError exception.

Prior to Python v3.8, the statistics.mode() method raises a StatisticsError exception if there is no most common element in the iterable, e.g. if the top two have the same number of occurrences.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Find the indices of duplicate items in a List in Python
• Find Max and Min in List without max() and min() in Python
• Find Min and Max values in Tuple or List of Tuples in Python
• Find the most/least common element in a List in Python
• Find object(s) in a List of objects in Python
• Find second Smallest or Largest number in a List in Python