192 Word Frequency 统计词频
Description:
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?
题目描述:
写一个 bash 脚本以统计一个文本文件 words.txt 中每个单词出现的频率。
为了简单起见，你可以假设：
words.txt只包括小写字母和 ' ' 。
每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 内容如下：
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:
不要担心词频相同的单词的排序问题，每个单词出现的频率都是唯一的。
你可以使用一行 Unix pipes 实现吗？
思路:
cat ——浏览文件
tr -s ——替换字符串（空格换为换行）保证了一行一个单词
sort ——默认ASCII值排序，排序号后还会有重复
uniq —— 去重，-c再输出重复次数。结果就是 ”4 abc“ abc出现了4次
sort -r —— 反向排序，也就是从大到小。得到按频率高低的结果
awk ——格式化输出，规定输出是先字符串再重复次数，所以先1，中间空格分隔
代码:
Bash:
# Read from the file words.txt and output the word frequency list to stdout.
cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r | awk '{print $2" "$1}'
