reshape dataframe based on a string split in one column in R

Question

I have the following data structure

ID  Type  Values
1   A     5; 7; 8
2   A     6
3   B     2; 3

and I would like to reshape it to the fol

Answer 1

The answers so far are great. Here's yet another.

# The data
DF <- data.frame(ID=1:3,
                 Type=c('A','A','B'), 
                 Values=c(' 5; 7; 8', '6', ' 2;3'))

This solution uses the colsplit() function from the "reshape2" package. One downside is that it expects you to know the number of resulting columns needed.

require(reshape2)
DF2 <- data.frame(DF[-3], colsplit(DF$Values, ";", c("V.1", "V.2", "V.3")))
na.omit(melt(DF2, id.vars=c("ID", "Type")))
#   ID Type variable value
# 1  1    A      V.1     5
# 2  2    A      V.1     6
# 3  3    B      V.1     2
# 4  1    A      V.2     7
# 6  3    B      V.2     3
# 7  1    A      V.3     8

From here you can sort and drop columns as required to get your final desired output.