使用正则表达式在折叠的单词之间插入空格 [英] Use regex to insert space between collapsed words

问题描述

我正在研究R中的一个弦乐，需要能够将状态名称与match.map()进行匹配.我正在使用的数据集将多个单词的名称放在一起，例如NorthDakota和DistrictOfColumbia.

I'm working on a choropleth in R and need to be able to match state names with match.map(). The dataset I'm using sticks multi-word names together, like NorthDakota and DistrictOfColumbia.

如何使用正则表达式在上下字母序列之间插入空格?我已经成功添加了一个空格，但是无法保留表示该空格的字母.

How can I use regular expressions to insert a space between lower-upper letter sequences? I've successfully added a space but haven't been able to preserve the letters that indicate where the space goes.

places = c("NorthDakota", "DistrictOfColumbia")
gsub("[[:lower:]][[:upper:]]", " ", places)
[1] "Nort akota"       "Distric  olumbia"

推荐答案

使用括号捕获匹配的表达式，然后使用\n(R中的\\n)检索它们:

Use parentheses to capture the matched expressions, then \n (\\n in R) to retrieve them:

places = c("NorthDakota", "DistrictOfColumbia")
gsub("([[:lower:]])([[:upper:]])", "\\1 \\2", places)
## [1] "North Dakota"         "District Of Columbia"

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