Perl | Count the frequency of words in text

Last Updated : 12 Feb, 2019

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.

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