192. Word Frequency

Write a bash script to calculate the frequency of each word in a text file words.txt.

For simplicity sake, you may assume:

• words.txt contains only lowercase characters and space ’ ’ characters.
• Each word must consist of lowercase characters only.
• Words are separated by one or more whitespace characters.
   

Example:

Assume that words.txt has the following content:
the day is sunny the the
the sunny is is
Your script should output the following, sorted by descending frequency:
the 4
is 3
sunny 2
day 1

From: LeetCode
Link: 192. Word Frequency

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Solution:

Ideas:

1. cat words.txt reads the content of words.txt.
2. tr -s ’ ’ ‘\n’ replaces one or more spaces with a newline character, so each word is on a new line.
3. sort sorts the words alphabetically.
4. uniq -c counts the occurrences of each unique word.
5. sort -nr sorts the lines in numerical reverse order based on the count.
6. awk ‘{print $2, $1}’ reorders the output to show the word first and its frequency second.

Code:

cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -nr | awk '{print $2, $1}'