[Bash]LeetCode192. 统计词频 | Word Frequency

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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?

---

写一个 bash 脚本以统计一个文本文件 words.txt 中每一个单词出现的频率。

为了简单起见，你能够假设：

• words.txt只包括小写字母和 ' ' 。
• 每一个单词只由小写字母组成。
• 单词间由一个或多个空格字符分隔。

示例:

假设 words.txt 内容以下：

the day is sunny the the
the sunny is is

你的脚本应当输出（以词频降序排列）：

the 4
is 3
sunny 2
day 1

说明:

• 不要担忧词频相同的单词的排序问题，每一个单词出现的频率都是惟一的。
• 你能够使用一行 Unix pipes 实现吗？

---

4ms

1 # Read from the file words.txt and output the word frequency list to stdout.
2 cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r | awk '{ print $2, $1 }'

---

8ms

1 # Read from the file words.txt and output the word frequency list to stdout.
2 awk '{
3     for (i = 1; i <= NF; ++i) ++s[$i];
4 } END {
5     for (i in s) print i, s[i];
6 }' words.txt | sort -nr -k 2

---

16ms

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