how to set assignement to fill subset by row - r

Question

While cleaning up a dataframe I found out that assignments into subsets works by columns and not by lines, an unfortunate result when doing dataset cleanup as you typically search cases of issues and then apply your correction across multiple lines.
# example table
releves <- structure(list(cult2015 = c("bp", "bp"), prec2015 = c("?", "?"
)), .Names = c("cult2015", "prec2015"), row.names = c(478L, 492L
), class = "data.frame")
# assignement to a subset
iBad2 <- which(releves$cult2015 == "bp" & releves$prec2015 == "?")
releves[iBad2,c("cult2015","prec2015")] <- c("b","p")
I understand that the "filling" of the matrices is done by columns and hence, the repetition of the provided vector is done on each column but is there any option to get: "b", "p" on each line and not:
> releves
cult2015 prec2015
478 b b
492 p p

Answer 1

I wrote the following function that does the job, at least in the cases I faced:
# allows to to assigment of newVals to a subset spanning over multiple rows
AssignToSubsetByRow <- function(dat,rows,cols,newVals){
if(is.null(dim(newVals))&length(rows)*length(cols)> length(newVals)){
fullRep <- rep(newVals,each=length(rows))
}else{
fullRep <- newVals
}
dat[rows,cols] <- fullRep
return(dat)
}
And doing the job fine:
releves <- AssignToSubsetByRow(releves,iBad2,c("cult2015","prec2015"),c("b","p"))
> releves
cult2015 prec2015
478 b p
492 b p