July 2017
Intermediate to advanced
398 pages
11h 54m
Chinese
Content preview from Python数据处理
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348
｜
附录
C
输入
exit
就可以退出
PowerShell
。提示符应该会变回
cmd
的标准提示符。输入
dir
Downloads\text_examples
，你应该会看到许多下载好的语料库文本文件。我们用
findstr
在这些文件中查找：
findstr "neat" Downloads\text_examples\*.txt
你应该会看到控制台中滚动输出了许多文本。它们是包含单词
neat
的文本文件中的匹配
行。
有时你想搜索特定的文件名，而不是文件中的字符串。你可以用
dir
命令加一个过滤器
（
filter
）来做到这一点：
dir -r -filter "*.txt"
这应该会找出主文件夹下所有子文件夹中的
.txt
文件。如果你需要继续在这些文件中搜索，
可以使用管道操作。
|
字符可以将第一个命令的输出通过管道传递给下一个命令。比如说，
我们可以用管道找到包含特定函数名的所有
Python
文件，或找到包含特定国家名称的所有
CSV
文件。我们试一下，将
findstr
的输出通过管道传递给
find
命令：
findstr /s "snake" *.txt | find /i "snake" /c
这段代码的作用是，首先找出包含单词
snake
的文本文件，然后利用
find
计算单词
snake
在这些文件中出现的次数。可以看出，学习更多
cmd
命令及其用法将有助于大大简化数据
处理人员和开发人员的很多任务，如搜索文件、运行代码、管理工作等。关于这一话题，
本附录介绍了一些内容，你可以在此基础上深入学习。
C.2.5
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.