“unpacking” a factor list from a data.frame

Question

I\'m new to R / having the option to easily re-organize data, and have hunted around for a solution but can\'t find exactly what I\'d like to do. Reshape2\'s melt/cast doesn

Answer 1

Another base R possibility using by:

do.call(rbind,
by(mydf,
   mydf$ID,
   function(x) {
     data.frame(
                ID=x$ID,
                category_list = unlist(strsplit(x$category_list,",")),
                xval=x$xval,
                yval=x$yval
               ) 
   }
  )
)

Result:

       ID category_list  xval  yval
ID1.1 ID1          cat1 xnum1 ynum1
ID1.2 ID1          cat2 xnum1 ynum1
ID1.3 ID1          cat3 xnum1 ynum1
ID2.1 ID2          cat2 xnum2 ynum2
ID2.2 ID2          cat3 xnum2 ynum2
ID3   ID3          cat1 xnum3 ynum3