Question
Formatted question description: https://leetcode.ca/all/192.html
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
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?
Process
NAME
tr
– translate characters
cat words.txt
the day is sunny the the
the sunny is is
cat words.txt | tr -s ' ' '\n'
the
day
is
sunny
the
the
the
sunny
is
is
words.txt | tr -s ' ' '\n' | sort
day
is
is
is
sunny
sunny
the
the
the
the
cat words.txt | tr -s ' ' '\n' | sort | uniq -c
1 day
3 is
2 sunny
4 the
cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r
4 the
3 is
2 sunny
1 day
cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r | awk '{ print $2, $1 }'
the 4
is 3
sunny 2
day 1
Wrong answer, if missing 1st sort
cat words.txt | tr -s ' ' '\n' | uniq -c | sort -r | awk '{ print $2, $1 }'
the 3
is 2
the 1
sunny 1
sunny 1
is 1
day 1
Code
Shell
# solution-1
# tr command is mainly used for character replacement or case replacement
# -s parameter means that if consecutive characters are found, reduce them to 1
# ‘ ’ And ‘\n’ are spaces and carriage returns, which means to replace all spaces with '\n'
cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r | awk '{ print $2, $1 }'
# solution-2
# grep -e is strictly the flag for indicating the pattern you want to match against.
# grep -E controls whether you need to escape certain special characters.
# grep -o means: Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line.
# sort -n, --numeric-sort, --sort=numeric
# sort -r, --reverse
grep -oE '[a-z]+' words.txt | sort | uniq -c | sort -nr | awk '{print $2" "$1}'