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

A data.table approach for coding elegance

library(data.table)
DT <- data.table(dat)
DT[, list(Value = unlist(strsplit(as.character(Values), '; '))), by = list(ID, Type)]