192. Word Frequency

Problem

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

Note:

• Don't worry about handling ties, it is guaranteed that each word's frequency count is unique.

• Could you write it in one-line using Unix pipes?

Solution

# Read from the file words.txt and output the word frequency list to stdout.
sed -e 's/ /\n/g' words.txt | sed -e '/^$/d' | sort | uniq -c | sort -r | awk '{print $2" "$1}'

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).