Find frequency of each word in a string in Python

31 Mar, 2020
Write a python code to find the frequency of each word in a given string.
Examples:
Input :  str[] = "Apple Mango Orange Mango Guava Guava Mango" 
Output : frequency of Apple is : 1
         frequency of Mango is : 3
         frequency of Orange is : 1
         frequency of Guava is : 2

Input :  str = "Train Bus Bus Train Taxi Aeroplane Taxi Bus"
Output : frequency of Train is : 2
         frequency of Bus is : 3
         frequency of Taxi is : 2
         frequency of Aeroplane is : 1

Approach 1 using list():1. Split the string into a list containing the words by using split function (i.e. string.split()) in python with delimiter space.
Note:
string_name.split(separator) method is used to split the string 
by specified separator(delimiter) into the list.
If delimiter is not provided then white space is a separator. 

For example:
CODE   : str='This is my book'
         str.split()
OUTPUT : ['This', 'is', 'my', 'book']

2. Initialize a new empty list.3. Now append the word to the new list from previous string if that word is not present in the new list.4. Iterate over the new list and use count function (i.e. string.count(newstring[iteration])) to find the frequency of word at each iteration.
Note:
string_name.count(substring) is used to find no. of occurrence of 
substring in a given string.

For example:
CODE   : str='Apple Mango Apple'
         str.count('Apple')
         str2='Apple'
         str.count(str2)
OUTPUT : 2
         2

Python3
# Python code to find frequency of each worddef freq(str):      # break the string into list of words     str = str.split()             str2 = []      # loop till string values present in list str    for i in str:                       # checking for the duplicacy        if i not in str2:              # insert value in str2            str2.append(i)                   for i in range(0, len(str2)):          # count the frequency of each word(present         # in str2) in str and print        print('Frequency of', str2[i], 'is :', str.count(str2[i]))      def main():    str ='apple mango apple orange orange apple guava mango mango'    freq(str)                      if __name__=="__main__":    main()             # call main function
Output:
Frequency of  apple  is :  3
Frequency of  mango  is :  3
Frequency of  orange  is :  2
Frequency of  guava  is :  1

Approach 2 using set():1. Split the string into a list containing the words by using split function (i.e. string.split()) in python with delimiter space.2. Use set() method to remove a duplicate and to give a set of unique words3. Iterate over the set and use count function (i.e. string.count(newstring[iteration])) to find the frequency of word at each iteration.
Python3
# Python3 code to find frequency of each word# function for calculating the frequencydef freq(str):      # break the string into list of words    str_list = str.split()      # gives set of unique words    unique_words = set(str_list)          for words in unique_words :        print('Frequency of ', words , 'is :', str_list.count(words))  # driver codeif __name__ == "__main__":          str ='apple mango apple orange orange apple guava mango mango'          # calling the freq function    freq(str)
Output:
Frequency of  apple  is :  3
Frequency of  mango  is :  3
Frequency of  orange  is :  2
Frequency of  guava  is :  1

Approach 3 (Using Dictionary)
# Find frequency of each word in a string in Python# using dictionary.   def count(elements):    # check if each word has '.' at its last. If so then ignore '.'    if elements[-1] == '.':        elements = elements[0:len(elements) - 1]       # if there exists a key as "elements" then simply    # increase its value.    if elements in dictionary:        dictionary[elements] += 1       # if the dictionary does not have the key as "elements"     # then create a key "elements" and assign its value to 1.    else:        dictionary.update({elements: 1})      # driver input to check the program.   Sentence = "Apple Mango Orange Mango Guava Guava Mango"   # Declare a dictionarydictionary = {}   # split all the word of the string.lst = Sentence.split()   # take each word from lst and pass it to the method count.for elements in lst:    count(elements)   # print the keys and its corresponding values.for allKeys in dictionary:    print ("Frequency of ", allKeys, end = " ")    print (":", end = " ")    print (dictionary[allKeys], end = " ")    print()    # This code is contributed by Ronit Shrivastava.
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