

   RRooww IInnddeexxeess

        row(x, as.factor=FALSE)

   AArrgguummeennttss::

          x: a matrix.

   as.factor: a logical value indicating whether the value
             should be returned as a factor rather than as
             numeric.

   VVaalluuee::

        An integer matrix with the same dimensions as `x' and
        whose `ij'-th element is equal to `i'.

   SSeeee AAllssoo::

        `col' to get columns.

   EExxaammpplleess::

        x <- matrix(1:12, 3, 4)
        # extract the diagonal of a matrix
        dx <- x[row(x)==col(x)]
        dx

        # create an identity 5-by-5 matrix
        x <- matrix(0,nr=5,nc=5)
        x[row(x)==col(x)] <- 1
        x

