search for: rowmatch

Dear R help I was hoping you might be able to show me how to write a loop function take would ccomplish this task. library(prob) { a <- sample ( 1:20, 100, replace=T) b<-sample(5:24,100,replace=T) } dd <- data.frame(a,b) dd # code piece I am looking for if(subset(dd,c(1,23,ordered=F))is found))( print subset) else( continue evaluating subsets) subset(dd,isin(dd,c(1,23), ordered =

Hello I am trying to compare a vector with a Matrix's rows.The vector has the same length as the number of columns of the matrix, and I would like to find the row numbers where the matrix's row us the same as the given vector. What I am doing at the moment is using apply as follows: apply(Matrix,1,function(x)all(x%in%LHS)) but this isn't too fast actually. I would like to know if

I am looking for a fast way to count the number of rows in a matrix are identical to a pattern vector. For example, if I am interested in counting the number of row vectors in a matrix that are identical to (1,2,3) what would I do? I have tried the identical statement in a loop but this is far too slow. I have a very large matrix and need to avoid loops at all costs. Thanks for any help.