[R] how to add a column from another dataset with "merge"

[Pete Brecknock]

kiotoqq wrote
> I want to add a shorter column to my dataset with the function "merge", 
> it
> should be filled with NAs wo be as long as the other colums, like this:
> 
> id    age
> 9    46
> 8    56
> 6   52
> 5   NA
> 4   NA
> 3  NA
> 1  NA
> 
> i did this:
> pa1 <- merge(pa1, an1, by="mergeid")
> 
> and it says "'by' must specify uniquely valid column(s)"

how about ...

#Data
d1<-data.frame(id=c(9,8,6,4,4,3,1))
d2<-data.frame(id=c(9,8,6),age=c(46,56,52))

# Left Merge
d<-merge(d1,d2,all.x=TRUE)

# Reorder
d[order(d$id,decreasing=TRUE),]

HTH

Pete



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