/*
* Copyright 2009-2020 The VOTCA Development Team
* (http://www.votca.org)
*
* 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.
*
*/
// Local VOTCA includes
#include "votca/xtp/statefilter_base.h"
namespace votca {
namespace xtp {
template <bool larger>
std::vector<Index> StateFilter_base::ReduceAndSortIndeces(
const Eigen::VectorXd& overlap, Index offset, double threshold) const {
std::vector<Index> index = std::vector<Index>(overlap.size());
std::iota(index.begin(), index.end(), offset);
std::stable_sort(index.begin(), index.end(), [&overlap](Index i1, Index i2) {
if (larger) {
return overlap[i1] > overlap[i2];
} else {
return overlap[i1] < overlap[i2];
}
});
Index validelements;
if (larger) {
validelements = (overlap.array() > threshold).sum();
} else {
validelements = (overlap.array() < threshold).sum();
}
std::vector<Index> indexes(validelements);
std::copy_n(index.begin(), validelements, indexes.begin());
return indexes;
}
std::vector<Index> StateFilter_base::ReduceAndSortIndecesUp(
const Eigen::VectorXd& overlap, Index offset, double threshold) const {
return ReduceAndSortIndeces<true>(overlap, offset, threshold);
}
std::vector<Index> StateFilter_base::ReduceAndSortIndecesDown(
const Eigen::VectorXd& overlap, Index offset, double threshold) const {
return ReduceAndSortIndeces<false>(overlap, offset, threshold);
}
} // namespace xtp
} // namespace votca