scripts/builtin/raSelection.dml

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

# This raSelection-function takes a matrix data set as input from where it performs
# relational operations : selection
#
# INPUT:
# ------------------------------------------------------------------------------
# X         Matrix of input data [shape: N x M]
# col       Integer indicating the column index to execute selection command
# op        String specifying the comparison operator (e.g., ">", "<", "==").
# val       Constant value to compare the column values "with col op val"
# ------------------------------------------------------------------------------
#
# OUTPUT:
# ------------------------------------------------------------------------------
# Y         Matrix of selected data [shape N' x M] with N' <= N
# ------------------------------------------------------------------------------

m_raSelection = function (Matrix[Double] X, Integer col, String op, Double val)
  return (Matrix[Double] Y)
{
  # Determine the operators
  I = ifelse(op == "==", X[,col] == val,
        ifelse(op == "!=", X[,col] != val,
        ifelse(op == "<",  X[,col] <  val,
        ifelse(op == ">",  X[,col] >  val,
        ifelse(op == "<=", X[,col] <= val,
        X[,col] >= val)))))

  # Perform actual selection
  Y = removeEmpty(target=X, margin="rows", select=I);
}