R统计：如何精确地拼写一个单词 [英] R statistics: How to grep a word exactly

问题描述

我想在下面的字符向量中寻找氮，并且想要只返回含有氮的条目并且没有其他条目（例如固氮）：
：

I'd like to grep for "nitrogen" in the following character vector and want to get back only the entry which is containing "nitrogen" and nothing of the rest (e.g. nitrogen fixation):

varnames=c("nitrogen", "dissolved organic nitrogen", "nitrogen fixation", "total dissolved nitrogen", "total nitrogen")

我试过这样的事情：

grepl(pattern= "![[:space:]]nitrogen![[:space:]]", varnames)

但这不起作用。我希望有人可以帮助我完成这项任务。

But this doesn't work. I hope somebody can help me with this task.

推荐答案

要获得与氮完全相同的索引，您可以使用

To get the indices that are exactly equal to "nitrogen" you could use

which(varnames == "nitrogen")

根据你想要做什么，你可能甚至不需要'which'作为 varnames ==nitrogen给出逻辑向量TRUE / FALSE。如果你只是想用氧气来代替所有的氮气的出现，这应该就足够了

Depending on what you want to do you might not even need the 'which' as varnames == "nitrogen" gives a logical vector of TRUE/FALSE. If you just want to do something like replace all of the occurances of "nitrogen" with "oxygen" this should suffice

varnames[varnames == "nitrogen"] <- "oxygen"

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