Grepl在R期间？ [英] Grepl for period in R?

问题描述

可以说我有一个字符串你好。我想看看这个字符串是否包含句点：

  text<  - Hello。 
 results<  -  grepl（。，text）
  

结果为TRUE ，但如果文本是你好，它也会返回。我非常困惑，在文档中我找不到任何关于这个的内容，它只在这段时间内做到这一点。

有什么想法？

谢谢！

解决方案

 > grepl（\\。，Hello。）
 [1] TRUE 
> grepl（\\。，Hello）
 [1] FALSE 
  

。表示SimonO101指出的任何内容，如果您想查找明确的。，那么您必须使用 \\。来表示查找。

R文档在正则表达式上很广泛，您还可以查看此链接以了解点的用法。

Lets say I have a string "Hello." I want to see if this string contains a period:

text <- "Hello."
results <- grepl(".",text)

This returns results as TRUE, but it would return that as well if text is "Hello". I'm extremely confused, I can't find anything about this in the documentation and it only does this for the period.

Any ideas?

Thanks!

解决方案

See the differences with these examples

 > grepl("\\.", "Hello.")
[1] TRUE
> grepl("\\.", "Hello")
[1] FALSE

the . means anything as pointed out by SimonO101, if you want to look for an explicit . then you have to skip it by using \\. which means look for a .

R documentation is extensive on regular expressions, you can also take a look at this link to understand the use of the dot.

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