将表转变为扁平格式（即去列联化）
table2flat<-function(mytable){
df<-as.data.frame(mytable)
rows<-dim(df)[1]
cols<-dim(df)[2]
x<-NULL
for(i in 1:rows){
for (j in 1:df$Freq[i]) {
row<-df[i,c(1:(cols-1))]
x<-rbind(x,row)
}
}
row.names(x)<-c(1:dim(x)[1])
return(x)
}
treatment<-rep(c('placebo','treated'),times=3)
improved<-rep(c('None','Some','Marked'),each=2)
Freq<-c(29,13,7,17,7,21)
mytable<-as.data.frame(cbind(treatment,improved,Freq))
mydata<-table2flat(mytable)
