#-------------------------------------------------------------
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
#
#-------------------------------------------------------------

# Builtin function that implements difference operation on vectors
#
# INPUT:
# -------------------------------------------------------
# X     input vector
# Y     input vector
# -------------------------------------------------------
#
# OUTPUT:
# -----------------------------------------------------------------
# R     vector with all elements that are present in X but not in Y
# -----------------------------------------------------------------

m_setdiff = function(Matrix[double] X, Matrix[double] Y)
  return (matrix[double] R)
{
  common = intersect(X, Y);
  X = unique(X);
  combined = order(target=rbind(X,common), by=1, decreasing=FALSE, index.return=FALSE);
  temp = combined[1:nrow(combined)-1,] != combined[2:nrow(combined),];
  mask = rbind(temp, matrix(1, 1, 1))
       & rbind(matrix(1, 1, 1), temp);
  R = removeEmpty(target = combined, margin = "rows", select = mask);
}
