scripts/builtin/setdiff.dml

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#-------------------------------------------------------------

# 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);
}