Question

I have a data set that looks like this

Code   Product
1      A|B
2      A|B|C
3      A|B|C|D|E

When I split the column Product using colsplit function, duplication occurs. The output of colsplit function looks like this:

Code  Product.1   Product.2  Product.3  Product.4  Product.5
1     A           B          A          B          A
2     A           B          C          A          B
3     A           B          C          D          E

This happens because one of the cells had five elements. Is there any way to avoid this duplication?

Thanks and regards
Jayaram

Answer 1

Update (21 Oct 2013)

The concepts below have been rolled into a family of functions called concat.split.* in my “splitstackshape” package. Here is a very straightforward solution using concat.split.multiple:

library(splitstackshape)
concat.split.multiple(temp, "Product", "|", "long")
#    Code time Product
# 1     1    1       A
# 2     2    1       A
# 3     3    1       A
# 4     1    2       B
# 5     2    2       B
# 6     3    2       B
# 7     1    3    <NA>
# 8     2    3       C
# 9     3    3       C
# 10    1    4    <NA>
# 11    2    4    <NA>
# 12    3    4       D
# 13    1    5    <NA>
# 14    2    5    <NA>
# 15    3    5       E

Remove the "long" argument if you want the wide format, but your comments indicated that ultimately you wanted a long format for your output.

---

Original answer (17 Dec 2012)

You can do this with strsplit and sapply as follows:

# Your data
temp <- structure(list(Code = 1:3, Product = c("A|B", "A|B|C", "A|B|C|D|E"
)), .Names = c("Code", "Product"), class = "data.frame", row.names = c(NA, -3L))

temp1 <- strsplit(temp$Product, "\\|") # Split the product cell
temp1 <- data.frame(Code = temp$Code, 
                    t(sapply(temp1, 
                           function(x) { 
                               temp <- matrix(NA, 
                                              nrow = max(sapply(temp1, length)));
                               temp[1:length(x)] <- x; temp})))
temp1
#   Code X1 X2   X3   X4   X5
# 1    1  A  B <NA> <NA> <NA>
# 2    2  A  B    C <NA> <NA>
# 3    3  A  B    C    D    E

---

Or… use rbind.fill from the “plyr” package, after making each of your rows into a single column data.frame:

temp1 <- strsplit(temp$Product, "\\|")
library(plyr)
data.frame(Code = temp$Code, 
           rbind.fill(lapply(temp1, function(x) data.frame(t(x)))))
#   Code X1 X2   X3   X4   X5
# 1    1  A  B <NA> <NA> <NA>
# 2    2  A  B    C <NA> <NA>
# 3    3  A  B    C    D    E

---

Or… inspired by @DWin’s great answer here, re-read the second column as a data.frame in itself.

newcols <- max(sapply(strsplit(temp$Product, "\\|"), length))
temp2 <- data.frame(Code = temp$Code,
                    read.table(text = as.character(temp$Product), 
                               sep="|", fill=TRUE, 
                               col.names=paste("Product", seq(newcols))))
temp2
#   Code Product.1 Product.2 Product.3 Product.4 Product.5
# 1    1         A         B                              
# 2    2         A         B         C                    
# 3    3         A         B         C         D         E