| // Copyright (c) 2022, ETH Zurich and UNC Chapel Hill. | |
| // All rights reserved. | |
| // | |
| // Redistribution and use in source and binary forms, with or without | |
| // modification, are permitted provided that the following conditions are met: | |
| // | |
| // * Redistributions of source code must retain the above copyright | |
| // notice, this list of conditions and the following disclaimer. | |
| // | |
| // * Redistributions in binary form must reproduce the above copyright | |
| // notice, this list of conditions and the following disclaimer in the | |
| // documentation and/or other materials provided with the distribution. | |
| // | |
| // * Neither the name of ETH Zurich and UNC Chapel Hill nor the names of | |
| // its contributors may be used to endorse or promote products derived | |
| // from this software without specific prior written permission. | |
| // | |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
| // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
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| // | |
| // Author: Johannes L. Schoenberger (jsch-at-demuc-dot-de) | |
| namespace colmap { | |
| CombinationSampler::CombinationSampler(const size_t num_samples) | |
| : num_samples_(num_samples) {} | |
| void CombinationSampler::Initialize(const size_t total_num_samples) { | |
| CHECK_LE(num_samples_, total_num_samples); | |
| total_sample_idxs_.resize(total_num_samples); | |
| // Note that the samples must be in increasing order for `NextCombination`. | |
| std::iota(total_sample_idxs_.begin(), total_sample_idxs_.end(), 0); | |
| } | |
| size_t CombinationSampler::MaxNumSamples() { | |
| return NChooseK(total_sample_idxs_.size(), num_samples_); | |
| } | |
| std::vector<size_t> CombinationSampler::Sample() { | |
| std::vector<size_t> sampled_idxs(num_samples_); | |
| for (size_t i = 0; i < num_samples_; ++i) { | |
| sampled_idxs[i] = total_sample_idxs_[i]; | |
| } | |
| if (!NextCombination(total_sample_idxs_.begin(), | |
| total_sample_idxs_.begin() + num_samples_, | |
| total_sample_idxs_.end())) { | |
| // Reached all possible combinations, so reset to original state. | |
| // Note that the samples must be in increasing order for `NextCombination`. | |
| std::iota(total_sample_idxs_.begin(), total_sample_idxs_.end(), 0); | |
| } | |
| return sampled_idxs; | |
| } | |
| } // namespace colmap | |