X<-read.csv('e:/BH.csv',header=T)
Y<-read.csv('e:/SJ.csv',header=T)
Z<-matrix(, nrow=55,ncol=2)
for(i in 1:55)
{ID1<-X[i,2]
for(n in 1:5648){
ID2<-Y[n,1]
if(ID==DD){
Z[n,1]<-Y[n,2]
Z[n,2]<-Y[n,3]
}}}
write.csv(Z,file ='e:/jg.csv',row.names = F)

R报错错误于Ops.factor(ID1, ID2) : 因子的层次集不同，怎么回事，如何解决？？？
跪求！