How to separate a string of digits and letters of various length into different columns in R?

Question

I have a column called 'WFBS' that has over a million rows of strings of different lengths that look like this:

WFBS <- c("M010203", "S01020304", "N104509")

and I need an output that looks like this:

WFBS1 <- c("M01", "S01", "N10")
WFBS2 <- c("02", "02", "45")
WFBS3 <- c("03", "03", "09")
WFBS4 <- c(NA, "04", NA)

So I need to separate each string in: first column: 3 characters (ie the letter followed by 2 digits) rest of the columns: 2 characters per column until I have no characters left

I tried using the function strsplit, but it says that my variables are not characters, so then I created a vector x as follows:

x <- as.character(WFBS)

but then I don't know how to separate the string into columns with the function strsplit.

Answer 1

An option with base R bu creating a delimiter , using sub , read with read.csv to create a 4 column data.frame

read.csv(text = sub("^(...)(..)(..)(.*)", "\\1,\\2,\\3,\\4", WFBS), 
  header = FALSE, colClasses = rep("character", 4), na.strings = "",
        col.names =paste0("WFBS", 1:4), stringsAsFactors = FALSE)
#    WFBS1 WFBS2 WFBS3 WFBS4
#1   M01    02    03  <NA>
#2   S01    02    03    04
#3   N10    45    09  <NA>

Answer 2

This might be a useful starting point:

library(tidyr)
df <- data.frame(WFBS = c("M010203", "S01020304", "N104509"),
                 stringsAsFactors = FALSE)
> df %>% separate(col = WFBS,
                  into = c("WFBS1","WFBS2","WFBS3","WFBS4"),
                  sep = c(3,5,7))
  WFBS1 WFBS2 WFBS3 WFBS4
1   M01    02    03      
2   S01    02    03    04
3   N10    45    09      

This leaves you with empty strings rather than NAs in the remainder spots, which you'd have to convert.