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我有这样一个文件的名称:name1.csv我想提取这个字符串的两个子串.一个存储name1一个变量,另一个存储扩展csv,而不存在另一个变量中的点.

我一直在寻找是否有类似indexOfJava 的功能允许进行那种操作,但我还没有找到任何东西.

有帮助吗？

I have some data that looks like this:

    country agdp apop
1        US  100  100
2 Australia   50   50

The variable names are agdp and apop, but I would like them to be gdp and pop. My real data has many, many variables that all need that transformation.

And this is what my desired outcome:

 country gdp pop
1        US  100  100
2 Australia   50   50

Reproducible code below:

df <- data.frame(stringsAsFactors=FALSE,
     country = c("US", "Australia"),
        agdp = …