使用strsplit:

R> strsplit("name1.csv", "\.")[[1]]
[1] "name1" "csv"  
R> 

请注意，您 a) 需要对点进行转义(因为它是正则表达式的元字符)并且 b) 处理 strsplit() 返回一个通常只有第一个列表的事实元素很有趣.

Note that you a) need to escape the dot (as it is a metacharacter for regular expressions) and b) deal with the fact that strsplit() returns a list of which typically only the first element is of interest.

更通用的解决方案涉及正则表达式，您可以在其中提取匹配项.

A more general solution involves regular expressions where you can extract the matches.

对于文件名的特殊情况，您还有:

For the special case of filenames you also have:

R> library(tools)   # unless already loaded, comes with base R
R> file_ext("name1.csv")
[1] "csv"
R> 

和

R> file_path_sans_ext("name1.csv")
[1] "name1"
R> 

因为这些是很常见的任务(参见 shell 中的 basename 等).

as these are such a common tasks (cf basename in shell etc).