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armadillo-code/include/armadillo_bits/glue_intersect_meat.hpp
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// 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 glue_intersect
//! @{
template<typename T1, typename T2>
inline
void
glue_intersect::apply(Mat<typename T1::elem_type>& out, const Glue<T1,T2,glue_intersect>& X)
{
arma_debug_sigprint();
uvec iA;
uvec iB;
glue_intersect::apply(out, iA, iB, X.A, X.B, false);
}
template<typename T1, typename T2>
inline
void
glue_intersect::apply(Mat<typename T1::elem_type>& out, uvec& iA, uvec& iB, const Base<typename T1::elem_type,T1>& A_expr, const Base<typename T1::elem_type,T2>& B_expr, const bool calc_indx)
{
arma_debug_sigprint();
typedef typename T1::elem_type eT;
const quasi_unwrap<T1> UA(A_expr.get_ref());
const quasi_unwrap<T2> UB(B_expr.get_ref());
if(UA.M.is_empty() || UB.M.is_empty())
{
out.reset();
iA.reset();
iB.reset();
return;
}
uvec A_uniq_indx;
uvec B_uniq_indx;
Mat<eT> A_uniq;
Mat<eT> B_uniq;
if(calc_indx)
{
A_uniq_indx = find_unique(UA.M);
B_uniq_indx = find_unique(UB.M);
A_uniq = UA.M.elem(A_uniq_indx);
B_uniq = UB.M.elem(B_uniq_indx);
}
else
{
A_uniq = unique(UA.M);
B_uniq = unique(UB.M);
}
const uword C_n_elem = A_uniq.n_elem + B_uniq.n_elem;
Col<eT> C(C_n_elem, arma_nozeros_indicator());
arrayops::copy(C.memptr(), A_uniq.memptr(), A_uniq.n_elem);
arrayops::copy(C.memptr() + A_uniq.n_elem, B_uniq.memptr(), B_uniq.n_elem);
uvec C_sorted_indx;
Col<eT> C_sorted;
if(calc_indx)
{
C_sorted_indx = stable_sort_index(C);
C_sorted = C.elem(C_sorted_indx);
}
else
{
C_sorted = sort(C);
}
const eT* C_sorted_mem = C_sorted.memptr();
uvec jj(C_n_elem, arma_nozeros_indicator()); // worst case length
uword* jj_mem = jj.memptr();
uword jj_count = 0;
for(uword i=0; i < (C_n_elem-1); ++i)
{
if( C_sorted_mem[i] == C_sorted_mem[i+1] )
{
jj_mem[jj_count] = i;
++jj_count;
}
}
if(jj_count == 0)
{
out.reset();
iA.reset();
iB.reset();
return;
}
const uvec ii(jj.memptr(), jj_count, false);
if(UA.M.is_rowvec() && UB.M.is_rowvec())
{
out.set_size(1, ii.n_elem);
Mat<eT> out_alias(out.memptr(), ii.n_elem, 1, false, true);
// NOTE: this relies on .elem() not changing the size of the output and not reallocating memory for the output
out_alias = C_sorted.elem(ii);
}
else
{
out = C_sorted.elem(ii);
}
if(calc_indx)
{
iA = A_uniq_indx.elem(C_sorted_indx.elem(ii ) );
iB = B_uniq_indx.elem(C_sorted_indx.elem(ii+1) - A_uniq.n_elem);
}
}
//! @}