Wrap new row based on condition from column

Question

I have a dataset that has following format:

id1 a1 b2 x1;x2;x3
id2 a2 b3 x4;x5
id3 a4 b5 x6
id4 a7 b7 x7;x8

First 3 columns (id, a, b) only have 1 instance, but the last column has multiple instances, separated by ;. How can I "wrap" these into new columns? Such as:

id1 a1 b2 x1
id1 a1 b2 x2
id1 a1 b2 x3
id2 a2 b3 x4
id2 a2 b3 x5
id3 a4 b5 x6
id4 a7 b7 x7
id4 a7 b7 x8

Answer 1

We can use cSplit

library(splitstackshape)
cSplit(df1, "v4", ";", "long")
#    v1 v2 v3 v4
#1: id1 a1 b2 x1
#2: id1 a1 b2 x2
#3: id1 a1 b2 x3
#4: id2 a2 b3 x4
#5: id2 a2 b3 x5
#6: id3 a4 b5 x6
#7: id4 a7 b7 x7
#8: id4 a7 b7 x8

data

df1 <- structure(list(v1 = c("id1", "id2", "id3", "id4"), v2 = c("a1", 
"a2", "a4", "a7"), v3 = c("b2", "b3", "b5", "b7"), v4 = c("x1;x2;x3", 
"x4;x5", "x6", "x7;x8")), .Names = c("v1", "v2", "v3", "v4"), 
 class = "data.frame", row.names = c(NA, -4L))