word-frequency

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Shell

Write a bash script to calculate the frequency of each word in a text file <code>words.txt</code>.

For simplicity sake, you may assume:

<ul>
	<li><code>words.txt</code> contains only lowercase characters and space <code>&#39; &#39;</code> characters.</li>
	<li>Each word must consist of lowercase characters only.</li>
	<li>Words are separated by one or more whitespace characters.</li>
</ul>

Example:

Assume that <code>words.txt</code> has the following content:

<pre>
the day is sunny the the
the sunny is is
</pre>

Your script should output the following, sorted by descending frequency:

<pre>
the 4
is 3
sunny 2
day 1
</pre>

Note:

<ul>
	<li>Don&#39;t worry about handling ties, it is guaranteed that each word&#39;s frequency count is unique.</li>
	<li>Could you write it in one-line using <a href="http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-4.html">Unix pipes</a>?</li>
</ul>

Word Frequency

Top K Frequent Elements

top-k-frequent-elements

前 K 个高频元素

写一个 bash 脚本以统计一个文本文件&nbsp;<code>words.txt</code>&nbsp;中每个单词出现的频率。

为了简单起见，你可以假设：

<ul>
	<li><code>words.txt</code>只包括小写字母和&nbsp;<code>' '</code>&nbsp;。</li>
	<li>每个单词只由小写字母组成。</li>
	<li>单词间由一个或多个空格字符分隔。</li>
</ul>

示例:

假设 <code>words.txt</code> 内容如下：

<pre>
the day is sunny the the
the sunny is is
</pre>

你的脚本应当输出（以词频降序排列）：

<pre>
the 4
is 3
sunny 2
day 1
</pre>

说明:

<ul>
	<li>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。</li>
	<li>你可以使用一行&nbsp;<a href="http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-4.html">Unix pipes</a>&nbsp;实现吗？</li>
</ul>