grepl 一段“."在R? [英] grepl for a period "." in R?

问题描述

假设我有一个字符串Hello".我想看看这个字符串是否包含句点:

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

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

这将返回结果为 TRUE，但如果文本是 "Hello" 没有句点，它也会返回结果.

This returns results as TRUE, but it would return that as well if text is "Hello" without the period.

我很困惑，我在文档中找不到任何关于此的信息，而且它仅在此期间执行此操作.

I'm confused, I can't find anything about this in the documentation and it only does this for the period.

有什么想法吗?

推荐答案

查看与这些示例的不同之处

See the differences with these examples

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

. 表示 SimonO101 指出的任何内容，如果您想查找显式的 . 那么您必须使用 \\ 跳过它. 表示寻找 .

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 文档在正则表达式方面非常广泛，您也可以查看此链接以了解其用法点.

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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