截断R中某个字符的字符串

Question

我在R中有一个字符串列表,如下所示:

WDN.TO
WDR.N
WDS.AX
WEC.AX
WEC.N
WED.TO

我想从字符"."开始获取字符串的所有后缀,结果应如下所示:

.TO
.N
.AX
.AX
.N
.TO

有人有主意吗？

Answer 1

约书亚的解决方案很好.我会用sub而不是gsub.gsub用于替换字符串中多次出现的模式 - sub是一次出现的.模式也可以简化一下:

> x <- c("WDN.TO","WDR.N","WDS.AX","WEC.AX","WEC.N","WED.TO")
> sub("^[^.]*", "", x)
[1] ".TO" ".N"  ".AX" ".AX" ".N"  ".TO"

...但是如果字符串与问题中的字符串一样规则,那么简单地剥离前3个字符就足够了:

> x <- c("WDN.TO","WDR.N","WDS.AX","WEC.AX","WEC.N","WED.TO")
> substring(x, 4)
[1] ".TO" ".N"  ".AX" ".AX" ".N"  ".TO"

Answer 2

使用gsub:

x <- c("WDN.TO","WDS.N")
# replace everything from the start of the string to the "." with "."
gsub("^.*\\.",".",x)
# [1] ".TO" ".N" 

使用strsplit:

# strsplit returns a list; use sapply to get the 2nd obs of each list element
y <- sapply(strsplit(x,"\\."), `[`, 2)
# since we split on ".", we need to put it back
paste(".",y,sep="")
# [1] ".TO" ".N"