split string at first number

Question

I would like to split strings between the last letter and first number:

dat <- read.table(text = "
        x         y    
        a1        0.1
        a2        0.2
        a3        0.3
        a4        0.4
        df1       0.1
        df2       0.2
        df13      0.3
        df24      0.4
        fcs111    0.1
        fcs912    0.2
        fcs113    0.3
        fcsb8114  0.4", 
 header=TRUE, stringsAsFactors=FALSE)

desired.result <- read.table(text = "
        x1    x2     y    
        a     1      0.1
        a     2      0.2
        a     3      0.3
        a     4      0.4
        df    1      0.1
        df    2      0.2
        df    13     0.3
        df    24     0.4
        fcs   111    0.1
        fcs   912    0.2
        fcs   113    0.3
        fcsb  8114   0.4", 
 header=TRUE, stringsAsFactors=FALSE)

There are a number of similar questions on StackOverflow, but I cannot find this exact situation. I know this must be a basic question. If I put a couple of hours into it I could probably figure it out. Sorry. Thank you for any suggestions. I prefer base R. If this is a duplicate I can delete it.

Answer 1

You can use lookarounds:

(?<=[a-zA-Z])(?=[0-9])

Answer 2

You can use strsplit function and provide regex pattern for split argument

cbind(dat, do.call(rbind, strsplit(dat$x, split = "(?<=[a-zA-Z])(?=[0-9])", perl = T)))
##           x   y    1    2
## 1        a1 0.1    a    1
## 2        a2 0.2    a    2
## 3        a3 0.3    a    3
## 4        a4 0.4    a    4
## 5       df1 0.1   df    1
## 6       df2 0.2   df    2
## 7      df13 0.3   df   13
## 8      df24 0.4   df   24
## 9    fcs111 0.1  fcs  111
## 10   fcs912 0.2  fcs  912
## 11   fcs113 0.3  fcs  113
## 12 fcsb8114 0.4 fcsb 8114