R:查找并删除所有一到两个字母的单词 [英] R: Find and remove all one to two letter words

问题描述

我正在尝试从文本段落中清除任何一个或两个字母的单词.这是我的第一个想法

I am attempting to clean away any one or two letter words from a text passage. This was my first thought

gsub(" [a-zA-Z]{1,2} ", " ", "a ab abc B BB BBB")
[1] "a aaa BB BBBB"

我可以看到a"是如何不被替换的，因为它没有以空格开头，我可以看到BB"是如何不被替换的，因为它所引导的空格已经被B"占据了.

I can see how the "a" is not replaced as it does not lead with a space and I can see how the "BB" is not replaced as the space it leads with has already been grabbed by the " B ".

推荐答案

你可以利用\b 词边界和[[:alpha:]] 括号表达式使用 {1,2} 限制量词，然后修剪前导/尾随空格并将多个空格缩小为 1:

You can make use of \b word boundary and [[:alpha:]] bracket expression with {1,2} limiting quantifier, and then trim the leading/trailing spaces and shrink multiple spaces into 1:

tr <- "a ab abc B BB BBB f"
tr <- gsub(" *\\b[[:alpha:]]{1,2}\\b *", " ", tr) # Remove 1-2 letter words
gsub("^ +| +$|( ) +", "\\1", tr) # Remove excessive spacing

结果:

[1] "abc BBB"

参见 IDEONE 演示

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