[leetcode][bash] 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.

For 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.

Hint:

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

<span style="font-size:18px;">cat words.txt|tr -s ' ' '\n'|sort|uniq -c|sort -rn|awk '{print $2, $1}'</span>
           

这一题提示用管道命令，我们就成全他

第一道工序：先将原文件格式整理一下，将所有的空格替换为换行符。（这里有个小疑惑，多余的空格并不会造成多次换行）

<span style="font-size:18px;">tr -s ' ' '\n'</span>
           

第二道工序：这里来了很常见的一个用法 sort|uniq -c 先通过sort将重复的数据按首字母排序放在一起，然后用uniq进行计数，是不是很像消除游戏的过程^_^，随后再进行一次排序，注意这里sort的两个参数，-r按题意降序排列，-n使用纯数字进行排序(默认是以文字类型来排序的) 

<span style="font-size:18px;">sort | uniq -c | sort -rn</span>
           

第三道工序：无关紧要的格式问题

<span style="font-size:18px;">awk ‘{ print $2，$1}’</span>
           

至此，问题就解决了

小弟首发技术博客，水平有限，主要是为了理清自己的思路，有助于别人，实乃非分之想，请大神们轻喷