scripts/builtin/unique.dml

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

# Builtin function that implements unique operation on vectors
#
# INPUT:
# -------------------------------------------------------
# X     input vector
# -------------------------------------------------------
#
# OUTPUT:
# -------------------------------------------------------------------
# R     matrix with only unique rows
# -------------------------------------------------------------------

m_unique = function(matrix[double] X)
  return (matrix[double] R)
{
  R = X
  if(nrow(X) > 1) {
    # sort-based approach (a generic alternative would be transformencode)
    X_sorted = order(target=X, by=1, decreasing=FALSE, index.return=FALSE);
    temp = X_sorted[1:nrow(X_sorted)-1,] != X_sorted[2:nrow(X_sorted),];
    mask = rbind(matrix(1, 1, 1), temp);
    R = removeEmpty(target = X_sorted, margin = "rows", select = mask);
  }
}