Perl | Count the frequency of words in text

Counting frequency of all words of a string is a basic operation for any programming language. The frequency of each word of the text can be counted and stored in a hash for further use. In Perl, we can do this by firstly splitting the words of the string into an array. We use the function split / / which splits the string with ‘ ‘. However the blank spaces can be more than one in between two words, therefore /\s+/ is used. Here \s+ denotes one or more occurrence of ‘ ‘. Now we traverse the new array created by splitting of text into words. This time we increment the count of the word while traversing the array.

• Example: To demonstrate Count the frequency of words in string

  # Perl program for counting words in a string
  
  $actual_text = "GFG GeeksforGeeks GFG" ;
  
  # Creating words array by splitting the string
  @words= split / /, $actual_text;
  
  # Traversing the words array and
  # increasing count of each word by 1
  foreach $word(@words)
  {
      $count{$word}++;
  }
  
  # Printing the word and its actual count
  foreach $word (sort keys %count)
  {
      print $word, " ", $count{$word}, "\n";
  }

  Output:

  GFG 2
  GeeksforGeeks 1
  

Difference between /\s+/ and / /: The ‘\s+’ can be used for a delimiter with one or many space. However / / just separates words with 1 space. The following code represents the difference if the text has more than one space between two words.

• Example: To demonstrate the difference between /\s+/ and / /

  
  # Perl program for counting words in a string using / /
  
  # A text with two spaces rather than one
  $actual_text = "GeeksforGeeks  welcomes you to GeeksforGeeks portal" ;
  
  # splitting the word with / /
  @words= split / /, $actual_text;
  
  # Counting the occurrence of each word
  foreach $word (@words)
  {
      $count{$word}++;
  }
  
  foreach $word (sort keys %count)
  {
      print $word, " ", $count{$word}, "\n";
  }

  Output:

  1
  GeeksforGeeks 2
  portal 1
  to 1
  welcomes 1
  you 1
  

  Note: The extra ‘ ‘ is also counted as a word.

Using the command /\s+/ to split the words: Here space will not count as the separate word.

• Example:

  
  #Perl program for counting words in a string using /\s+/
  
  # Actual string with two spaces
  $actual_text = "GeeksforGeeks  welcomes you to GeeksforGeeks portal" ;
  
  #S plitting the text using /\s+/ command
  @words = split /\s+/, $actual_text;
  
  # counting the occurrence of each word
  foreach $word (@words)
  {
      $count{$word}++;
  }
  
  foreach $word (sort keys %count)
  {
      print $word, " ", $count{$word}, "\n";
  }

  Output:

  GeeksforGeeks 2
  portal 1
  to 1
  welcomes 1
  you 1
  

  Note: The extra ‘ ‘ is not counted as a word.