151 lines
3.1 KiB
C++
151 lines
3.1 KiB
C++
// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
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// Copyright 2008-2016 National ICT Australia (NICTA)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// ------------------------------------------------------------------------
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//! \addtogroup fn_randperm
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//! @{
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template<typename obj_type>
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inline
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void
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internal_randperm_helper(obj_type& x, const uword N, const uword N_keep)
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{
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arma_extra_debug_sigprint();
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typedef typename obj_type::elem_type eT;
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// see op_sort_index_bones.hpp for the definition of arma_sort_index_packet
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typedef arma_sort_index_packet<int> packet;
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std::vector<packet> packet_vec(N);
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for(uword i=0; i < N; ++i)
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{
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packet_vec[i].val = int(arma_rng::randi<int>());
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packet_vec[i].index = i;
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}
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arma_sort_index_helper_ascend<int> comparator;
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if(N >= 2)
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{
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if(N_keep < N)
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{
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typename std::vector<packet>::iterator first = packet_vec.begin();
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typename std::vector<packet>::iterator nth = first + N_keep;
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typename std::vector<packet>::iterator pastlast = packet_vec.end();
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std::partial_sort(first, nth, pastlast, comparator);
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}
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else
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{
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std::sort( packet_vec.begin(), packet_vec.end(), comparator );
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}
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}
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if(is_Row<obj_type>::value)
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{
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x.set_size(1,N_keep);
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}
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else
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{
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x.set_size(N_keep,1);
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}
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eT* x_mem = x.memptr();
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for(uword i=0; i < N_keep; ++i)
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{
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x_mem[i] = eT( packet_vec[i].index );
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}
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}
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template<typename obj_type>
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arma_warn_unused
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inline
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typename enable_if2< is_Mat<obj_type>::value, obj_type >::result
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randperm(const uword N)
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{
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arma_extra_debug_sigprint();
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obj_type x;
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if(N > 0) { internal_randperm_helper(x, N, N); }
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return x;
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}
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arma_warn_unused
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inline
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uvec
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randperm(const uword N)
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{
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arma_extra_debug_sigprint();
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uvec x;
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if(N > 0) { internal_randperm_helper(x, N, N); }
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return x;
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}
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template<typename obj_type>
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arma_warn_unused
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inline
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typename enable_if2< is_Mat<obj_type>::value, obj_type >::result
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randperm(const uword N, const uword M)
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{
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arma_extra_debug_sigprint();
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arma_debug_check( (M > N), "randperm(): 'M' must be less than or equal to 'N'" );
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obj_type x;
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if( (N > 0) && (M > 0) ) { internal_randperm_helper(x, N, M); }
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return x;
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}
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arma_warn_unused
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inline
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uvec
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randperm(const uword N, const uword M)
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{
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arma_extra_debug_sigprint();
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arma_debug_check( (M > N), "randperm(): 'M' must be less than or equal to 'N'" );
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uvec x;
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if( (N > 0) && (M > 0) ) { internal_randperm_helper(x, N, M); }
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return x;
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}
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//! @}
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