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Copy data from Ellpack to GHist. (#8215)

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This commit is contained in:
Jiaming Yuan
2022-09-06 23:05:49 +08:00
committed by GitHub
parent 7ee10e3dbd
commit 441ffc017a
16 changed files with 466 additions and 112 deletions
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35
src/common/hist_util.h
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@@ -22,6 +22,7 @@
#include "row_set.h"
#include "threading_utils.h"
#include "timer.h"
#include "algorithm.h" // SegmentId
namespace xgboost {
class GHistIndexMatrix;
@@ -130,19 +131,23 @@ class HistogramCuts {
/**
* \brief Search the bin index for categorical feature.
*/
bst_bin_t SearchCatBin(float value, bst_feature_t fidx) const {
auto const &ptrs = this->Ptrs();
auto const &vals = this->Values();
bst_bin_t SearchCatBin(float value, bst_feature_t fidx, std::vector<uint32_t> const& ptrs,
std::vector<float> const& vals) const {
auto end = ptrs.at(fidx + 1) + vals.cbegin();
auto beg = ptrs[fidx] + vals.cbegin();
// Truncates the value in case it's not perfectly rounded.
auto v = static_cast<float>(common::AsCat(value));
auto v = static_cast<float>(common::AsCat(value));
auto bin_idx = std::lower_bound(beg, end, v) - vals.cbegin();
if (bin_idx == ptrs.at(fidx + 1)) {
bin_idx -= 1;
}
return bin_idx;
}
bst_bin_t SearchCatBin(float value, bst_feature_t fidx) const {
auto const& ptrs = this->Ptrs();
auto const& vals = this->Values();
return this->SearchCatBin(value, fidx, ptrs, vals);
}
bst_bin_t SearchCatBin(Entry const& e) const { return SearchCatBin(e.fvalue, e.index); }
};
@@ -189,6 +194,28 @@ auto DispatchBinType(BinTypeSize type, Fn&& fn) {
* storage class.
*/
struct Index {
// Inside the compressor, bin_idx is the index for cut value across all features. By
// subtracting it with starting pointer of each feature, we can reduce it to smaller
// value and store it with smaller types. Usable only with dense data.
//
// For sparse input we have to store an addition feature index (similar to sparse matrix
// formats like CSR) for each bin in index field to choose the right offset.
template <typename T>
struct CompressBin {
uint32_t const* offsets;
template <typename Bin, typename Feat>
auto operator()(Bin bin_idx, Feat fidx) const {
return static_cast<T>(bin_idx - offsets[fidx]);
}
};
template <typename T>
CompressBin<T> MakeCompressor() const {
uint32_t const* offsets = this->Offset();
return CompressBin<T>{offsets};
}
Index() { SetBinTypeSize(binTypeSize_); }
Index(const Index& i) = delete;
Index& operator=(Index i) = delete;