[R] dot products

Alexander Shenkin ashenkin at ufl.edu
Wed Mar 7 21:14:05 CET 2012


I need to take a dot product of each row of a dataframe and a vector.
The number of columns will be dynamic.  The way I've been doing it so
far is contorted.  Is there a better way?

    dotproduct <- function(dataf, v2) {
        apply(t(t(as.matrix(a)) * v2),1,sum) #contorted!

    df = data.frame(a=c(1,2,3),b=c(4,5,6))
    vec = c(4,5)
    dotproduct(df, vec)


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