用R取得逗号前的字符串

问题描述

我是R的初学者.现在，我在这样的data.frame中有一个向量

I am a beginner with R. Now, I have a vector in a data.frame like this

city
Kirkland,
Bethesda,
Wellington,
La Jolla,
Berkeley,
Costa, Evie KW172NJ
Miami,
Plano,
Sacramento,
Middletown,
Webster,
Houston,
Denver,
Kirkland,
Pinecrest,
Tarzana,
Boulder,
Westfield,
Fair Haven,
Royal Palm Beach, Fl
Westport,
Encino,
Oak Ridge,

我要清洁它.我要的是逗号前的所有城市名称.如何在R中得到结果?谢谢！

I want to clean it. What I want is all the city names before the comma. How can I get the result in R? Thanks!

推荐答案

您可以将gsub与regexp一起使用:

You can use gsub with a bit of regexp :

cities <- gsub("^(.*?),.*", "\\1", df$city)

这也是可行的:

cities <- gsub(",.*$", "", df$city)

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