如何拆分包含相等大小的字符串且值之间有空格的字符串向量，然后仅提取R中的几个值？
字符串向量可以包含任何值，包括空格。有时，也会读取带有一些空格的字符串向量，而我们想分割向量然后提取一些值。例如，如果一个字符串具有“ABC123”，那么我们可能要提取数字123，以便我们可以在分析中使用它。如果字符串向量具有相等大小的字符串，则可以在substr函数的帮助下轻松完成此操作。
例子
> x1<-c("1 00","1 01","1 02","1 03","1 03","1 04")
> x1
[1] "1 00" "1 01" "1 02" "1 03" "1 03" "1 04"
> Numeric_Last_two_x1<-substr(x1,start=4,stop=5)
> Numeric_Last_two_x1
[1] "00" "01" "02" "03" "03" "04"
> Numeric_Last_first_x1<-substr(x1,start=4,stop=4)
> Numeric_Last_first_x1
[1] "0" "0" "0" "0" "0" "0"
> Numeric_Last_last_x1<-substr(x1,start=5,stop=5)
> Numeric_Last_last_x1
[1] "0" "1" "2" "3" "3" "4"
> x2<-c("1 0","1 1","1 2","1 3","1 4","1 5")
> x2
[1] "1 0" "1 1" "1 2" "1 3" "1 4" "1 5"
> Last_value_x2<-substr(x2,start=4,stop=4)
> Last_value_x2
[1] "0" "1" "2" "3" "4" "5"
> First_value_x2<-substr(x2,start=1,stop=1)
> First_value_x2
[1] "1" "1" "1" "1" "1" "1"
> x3<-c("A 0","B 1","C 2","D 3","E 4","F 5")
> x3
[1] "A 0" "B 1" "C 2" "D 3" "E 4" "F 5"
> Last_value_x3<-substr(x3,start=4,stop=4)
> Last_value_x3
[1] "0" "1" "2" "3" "4" "5"
> x4<-c("A 1151","B 1152","C 1153","D 1154","E 1155","F 1156")
> x4
[1] "A 1151" "B 1152" "C 1153" "D 1154" "E 1155" "F 1156"
> Last_value_x4<-substr(x4,start=7,stop=7)
> Last_value_x4
[1] "1" "2" "3" "4" "5" "6"
> Last_three_value_x4<-substr(x4,start=5,stop=7)
> Last_three_value_x4
[1] "151" "152" "153" "154" "155" "156"
> Last_two_value_x4<-substr(x4,start=6,stop=7)
> Last_two_value_x4
[1] "51" "52" "53" "54" "55" "56"
> Last_numeric_value_x4<-substr(x4,start=4,stop=7)
> Last_numeric_value_x4
[1] "1151" "1152" "1153" "1154" "1155" "1156"
> x5<-c("System-1 191","System-2 352","System-3 498","System-4 154","System-5
327","System-6 456")
> x5
[1] "System-1 191" "System-2 352" "System-3 498" "System-4 154"
[5] "System-5 327" "System-6 456"
> Last_numeric_value_x5<-substr(x5,start=11,stop=13)
> Last_numeric_value_x5
[1] "191" "352" "498" "154" "327" "456"
> Last_digit_x5<-substr(x5,start=13,stop=13)
> Last_digit_x5
[1] "1" "2" "8" "4" "7" "6"
> Last_two_digits_x5<-substr(x5,start=12,stop=13)
> Last_two_digits_x5
[1] "91" "52" "98" "54" "27" "56"
> Digits_in_System_x5<-substr(x5,start=8,stop=8)
> Digits_in_System_x5
[1] "1" "2" "3" "4" "5" "6"