Error in `*tmp*`[[j]] : subscript out of bounds

for(i in 1:dim(dataset)[1]){
  hitlist=trainmy2[trainmy2$VisitNumber==dataset[i,2],]
  dayofweek=names(hitlist)[3:9][hitlist[1,3:9]>0]
  dataset[i,dayofweek]=1
  hitlist2=Copy_Walmart[Copy_Walmart$VisitNumber==dataset[i,2],]
  agg=aggregate(ScanCount~DepartmentDescription,data=hitlist2,sum)
  sub1<-gsub("",".",paste0(names(agg)[1],".",agg[,1]))
  sub2<-gsub("-",".",sub1)
  sub3<-gsub("&",".",sub2)
  sub4<-gsub("/",".",sub3)
  sub5<-gsub(",",".",sub4)
  dataset[i,sub5]=agg[,2]
  print(i)
}