armadillo-code/include/armadillo_bits/op_sort_meat.hpp

// SPDX-License-Identifier: Apache-2.0
// 
// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
// 
// Licensed 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.
// ------------------------------------------------------------------------


//! \addtogroup op_sort
//! @{



template<typename eT>
inline 
void
op_sort::direct_sort(eT* X, const uword n_elem, const uword sort_type)
  {
  arma_extra_debug_sigprint();
  
  if(sort_type == 0)
    {
    arma_lt_comparator<eT> comparator;
    
    std::sort(&X[0], &X[n_elem], comparator);
    }
  else
    {
    arma_gt_comparator<eT> comparator;
    
    std::sort(&X[0], &X[n_elem], comparator);
    }
  }



template<typename eT>
inline 
void
op_sort::direct_sort_ascending(eT* X, const uword n_elem)
  {
  arma_extra_debug_sigprint();
  
  arma_lt_comparator<eT> comparator;
    
  std::sort(&X[0], &X[n_elem], comparator);
  }



template<typename eT>
inline 
void
op_sort::copy_row(eT* X, const Mat<eT>& A, const uword row)
  {
  const uword N = A.n_cols;
  
  uword i,j;
  
  for(i=0, j=1; j<N; i+=2, j+=2)
    {
    X[i] = A.at(row,i);
    X[j] = A.at(row,j);
    }
  
  if(i < N)
    {
    X[i] = A.at(row,i);
    }
  }



template<typename eT>
inline 
void
op_sort::copy_row(Mat<eT>& A, const eT* X, const uword row)
  {
  const uword N = A.n_cols;
  
  uword i,j;
  
  for(i=0, j=1; j<N; i+=2, j+=2)
    {
    A.at(row,i) = X[i]; 
    A.at(row,j) = X[j];
    }
  
  if(i < N)
    {
    A.at(row,i) = X[i];
    }
  }



template<typename eT>
inline
void
op_sort::apply_noalias(Mat<eT>& out, const Mat<eT>& X, const uword sort_type, const uword dim)
  {
  arma_extra_debug_sigprint();
  
  if((X.n_rows * X.n_cols) <= 1)  { out = X; return; }
  
  if(dim == 0)  // sort the contents of each column
    {
    arma_extra_debug_print("op_sort::apply(): dim = 0");
    
    out = X;
    
    const uword n_rows = out.n_rows;
    const uword n_cols = out.n_cols;
      
    for(uword col=0; col < n_cols; ++col)
      {
      op_sort::direct_sort( out.colptr(col), n_rows, sort_type );
      }
    }
  else
  if(dim == 1)  // sort the contents of each row
    {
    if(X.n_rows == 1)  // a row vector
      {
      arma_extra_debug_print("op_sort::apply(): dim = 1, vector specific");
      
      out = X;
      op_sort::direct_sort(out.memptr(), out.n_elem, sort_type);
      }
    else  // not a row vector
      {
      arma_extra_debug_print("op_sort::apply(): dim = 1, generic");
      
      out.copy_size(X);
      
      const uword n_rows = out.n_rows;
      const uword n_cols = out.n_cols;
      
      podarray<eT> tmp_array(n_cols);
      
      for(uword row=0; row < n_rows; ++row)
        {
        op_sort::copy_row(tmp_array.memptr(), X, row);
        
        op_sort::direct_sort( tmp_array.memptr(), n_cols, sort_type );
        
        op_sort::copy_row(out, tmp_array.memptr(), row);
        }
      }
    }
  }



template<typename T1>
inline
void
op_sort::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_sort>& in)
  {
  arma_extra_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const quasi_unwrap<T1> U(in.m);
  const Mat<eT>&     X = U.M;
  
  const uword sort_type = in.aux_uword_a;
  const uword dim       = in.aux_uword_b;
  
  arma_debug_check( (sort_type > 1), "sort(): parameter 'sort_type' must be 0 or 1" );
  arma_debug_check( (dim > 1),       "sort(): parameter 'dim' must be 0 or 1"       );
  arma_debug_check( (X.has_nan()),   "sort(): detected NaN"                         );
  
  if(U.is_alias(out))
    {
    Mat<eT> tmp;
    
    op_sort::apply_noalias(tmp, X, sort_type, dim);
    
    out.steal_mem(tmp);
    }
  else
    {
    op_sort::apply_noalias(out, X, sort_type, dim);
    }
  }



template<typename T1>
inline
void
op_sort_vec::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_sort_vec>& in)
  {
  arma_extra_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const unwrap<T1>   U(in.m);  // not using quasi_unwrap, to ensure there is no aliasing with subviews
  const Mat<eT>& X = U.M;
  
  const uword sort_type = in.aux_uword_a;
  
  arma_debug_check( (sort_type > 1), "sort(): parameter 'sort_type' must be 0 or 1" );
  arma_debug_check( (X.has_nan()),   "sort(): detected NaN"                         );
  
  out = X;  // not checking for aliasing, to allow inplace sorting of vectors
  
  if(out.n_elem <= 1)  { return; }
  
  eT* out_mem = out.memptr();
  
  eT* start_ptr =  out_mem;
  eT* endp1_ptr = &out_mem[out.n_elem];
  
  if(sort_type == 0)
    {
    arma_lt_comparator<eT> comparator;
    
    std::sort(start_ptr, endp1_ptr, comparator);
    }
  else
    {
    arma_gt_comparator<eT> comparator;
    
    std::sort(start_ptr, endp1_ptr, comparator);
    }
  }



//! @}