Compute or check the structure of a cost matrix
costMatrix(y, C = c("0/1", "linear"))
a factor representing the labels of the instances
either a cost matrix to check for consistency with labels in y, or a character string defining the standard matrix to compute. If a character string the accepted values are "0/1" for a 0-1 cost matrix or "linear" for linear cost.
the cost matrix object
nrbm, ordinalRegressionLoss