R/my_groupMeans.R

In nclSLR: The nclSLR package.

my_groupMeans <-
  function(X, g)
  {
    # X: matrix of explanatory variables
    # g: factor with group memberships

    # how many groups
    ng = nlevels(g)
    # matrix with group means
    Means = matrix(0, ng, ncol(X))
    for (j in 1:ncol(X))
    {
      Means[,j] = tapply(X[,j], g, FUN=mean)
    }
    # add names
    rownames(Means) = levels(g)
    colnames(Means) = colnames(X)
    # results
    Means
  }