#-------------------------------------------------------------
#
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# 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
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# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
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#-------------------------------------------------------------

# This builtin function takes the outputs of SliceLine and allows
#
#
# INPUT:
# ------------------------------------------------------------------------------
# X       Feature matrix in recoded/binned representation
# e       Error vector of trained model
# TK      top-k slices (k x ncol(X) if successful)
# TKC     score, total/max error, size of slices (k x 4)
# k2      fist k2 slices to extract with k2 <= k
# ------------------------------------------------------------------------------
#
# OUTPUT:
# ------------------------------------------------------------------------------
# Xtk     Selected rows from X which belong to k2 top slices
# etk     Selected rows from e which belong to k2 top slices
# ------------------------------------------------------------------------------

m_sliceLineExtract = function(Matrix[Double] X, Matrix[Double] e,
  Matrix[Double] TK, Matrix[Double] TKC, Integer k2 = -1)
  return(Matrix[Double] Xtk, Matrix[Double] etk, Matrix[Double] I)
{
  # check valid parameters
  if( k2 > nrow(TK) )
    stop("sliceLineExtract: invalid number of slices to extract: "+k2+" > "+nrow(TK)).
  if( k2 <= 0 )
    k2 = nrow(TK);

  # extract first k2 slices from X and e
  I = matrix(0, k2, nrow(X));
  parfor(i in 1:k2) {
    I[i,] = t(rowSums(X == TK[i,]) == sum(TK[i,] > 0))
  }
  I = t(colSums(I)); #union

  Xtk = removeEmpty(target=X, margin="rows", select=I);
  etk = removeEmpty(target=e, margin="rows", select=I);
}