Kissell, Robert [EQRE] <robert.kissell <at> citigroup.com> writes:
> I would like to learn how I can group the data on unique rows of A and also count the number of times the row > occurred. You have already provided the answer, unique(A), to the first part of your question. Here are two solutions to the second part: 1. Since each row can be regarded as the representation of a binary number: table(A%*%2^(0:3)) 2. Another possibility not dependent on the binary nature of the data is to define: "%+.*%" <- function(a,b)apply(b,2,function(x)apply(t(a) == x,2,all)) This function is the +.x of APL. It defines an infix function that does a matrix multiply of matrix a and matrix b except it replaces the usual inner product of two vectors x and y with all(x==y). In terms of this function, the answer is: colSums( A %+.*% t(unique(A)) ) ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
