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Python | Frequency of each character in String
  • Difficulty Level : Medium
  • Last Updated : 22 Nov, 2018

Given a string, the task is to find the frequencies of all the characters in that string and return a dictionary with key as the character and its value as its frequency in the given string.

Method #1 : Naive method

Simply iterate through the string and form a key in dictionary of newly occurred element or if element is already occurred, increase its value by 1.




# Python3 code to demonstrate 
# each occurrence frequency using 
# naive method 
  
# initializing string 
test_str = "GeeksforGeeks"
  
# using naive method to get count 
# of each element in string 
all_freq = {}
  
for i in test_str:
    if i in all_freq:
        all_freq[i] += 1
    else:
        all_freq[i] = 1
  
# printing result 
print ("Count of all characters in GeeksforGeeks is :\n "
                                        +  str(all_freq))

Output :

Count of all characters in GeeksforGeeks is :
 {'r': 1, 'e': 4, 'k': 2, 'G': 2, 's': 2, 'f': 1, 'o': 1}

 



Method #2 : Using collections.Counter()

The most suggested method that could be used to find all occurrences is this method, this actually gets all element frequency and could also be used to print single element frequency if required.




# Python3 code to demonstrate 
# each occurrence frequency using 
# collections.Counter()
from collections import Counter
  
# initializing string 
test_str = "GeeksforGeeks"
  
# using collections.Counter() to get 
# count of each element in string 
res = Counter(test_str)
  
# printing result 
print ("Count of all characters in GeeksforGeeks is :\n "
                                           +  str(res))

Output :

Count of all characters in GeeksforGeeks is : 
Counter({'e': 4, 's': 2, 'k': 2, 'G': 2, 'o': 1, 'r': 1, 'f': 1})

 

Method #3 : Using dict.get()

get() method is used to check the previously occurring character in string, if its new, it assigns 0 as initial and appends 1 to it, else appends 1 to previously holded value of that element in dictionary.




# Python3 code to demonstrate 
# each occurrence frequency using 
# dict.get()
  
# initializing string 
test_str = "GeeksforGeeks"
  
# using dict.get() to get count 
# of each element in string 
res = {}
  
for keys in test_str:
    res[keys] = res.get(keys, 0) + 1
  
# printing result 
print ("Count of all characters in GeeksforGeeks is : \n"
                                             +  str(res))

Output :

Count of all characters in GeeksforGeeks is :
 {'k': 2, 'e': 4, 's': 2, 'G': 2, 'f': 1, 'r': 1, 'o': 1}

 

Method #4 : Using set() + count()

count() coupled with set() can also achieve this task, in this we just iterate over the set converted string and get the count of each character in original string and assign that element with that value counted using count().




# Python3 code to demonstrate 
# each occurrence frequency using 
# set() + count()
  
# initializing string 
test_str = "GeeksforGeeks"
  
# using set() + count() to get count 
# of each element in string 
res = {i : test_str.count(i) for i in set(test_str)}
  
# printing result 
print ("The count of all characters in GeeksforGeeks is :\n "
                                               +  str(res))

Output :

Count of all characters in GeeksforGeeks is :
 {'G': 2, 's': 2, 'k': 2, 'e': 4, 'o': 1, 'r': 1, 'f': 1}

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