[R] Splitting up rows in a data frame

[Tom Wenseleers]

Dear all,
I have the following data frame
goannot=read.table(file="c:\ApisGOannot.txt",colClasses="character",header=TRUE,sep="\t") 

         GB_nr           evidence                            GO_list
1       GB18414-RA     apis                             0001507, 
0003990, 0004104
2       GB10293-RA     apis                             0003676
3       GB12644-RA     apis                             0003677, 
0000786, 0006334, 0005634
4       GB17142-RA     apis                             0003677, 
0003899, 0006350
5       GB15064-RA     apis                             0003677, 0005515

and I would like to split up each row in the data frame based on the 
", " delimiter in the GO_list column. I.e. I would like to obtain
         GB_nr           evidence                            GO_list
1       GB18414-RA     apis                             0001507
2       GB18414-RA     apis                             0003990
3       GB18414-RA     apis                             0004104
4       GB10293-RA     apis                             0003676
5       GB12644-RA     apis                             0003677
6       GB12644-RA     apis                             0000786
7       GB12644-RA     apis                             0006334
8       GB12644-RA     apis                             0005634
...

I started to try to do this using strsplit, but I was thinking there 
might be more elegant ways to do this?
Any advice would be much appreciated (I am new to R)!

cheers,
Tom


Dr. T. Wenseleers
Dept. of Biology
Zoological Institute
K.U.Leuven
Naamsestraat 59
B-3000 Leuven
Belgium
tel. +32 (0)16 32 39 64
mobile +32 (0)472 40 45 96
e-mail tom.wenseleers at bio.kuleuven.be
web http://bio.kuleuven.be/ento/wenseleers/twenseleers.htm