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

有人有什么想法吗？

Answer 1

约书亚的解决方案很好。我会使用sub代替gsub。 gsub用于替换字符串中多次出现的模式 - sub用于一次出现。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"

...但如果字符串与问题中的字符串一样规则，那么只需剥离前3个字符即可：

> 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"

Answer 3

Strsplit可能会这样做，但如果数据集太大，则会显示错误下标超出范围

x <- c("WDN.TO","WDR.N","WDS.AX","WEC.AX","WEC.N","WED.TO")
y <- strsplit(x,".")[,2]
#output y= TO N AX AX N TO

截断R中某个字符的字符串

3 个答案: