Dear friends,
 my question is how to aggregate dataset  and the inverse manipulation.
e.g.My dataset
data structure1:
x
 1
1
2
3
3
data structure2:
x  freq
1  2
2  1
3  2
Then how to generate dataset2 from dataset1 and generate dataset1 from
dataset2?

e.g. dataset2 from dataset1 :
x<-c(1,1,2,3,3)
a<-tab(x)
as.data.frame(a)

*But i can't do the inverse manipulation:generate dataset1 from dataset2*,
anybody can help me on the two different manipulations?

Thanks a lot!





-- 
Kind Regards,
Zhi Jie,Zhang ,PHD
Department of Epidemiology
School of Public Health
Fudan University
Tel:86-21-54237149

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