I have a data frame `A` in which I want to search for a value `300` in `A$product_id`. I have `b<-300`. Now I use `ifelse(A$product_id%in%b,print("Yes"),print(""))` but I get a lot of "" as output when `A$product_id!=300` instead of blank space. I only want it to print yes when `A$product_id==300` otherwise do nothing.