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faiss::IndexIVFScalarQuantizer Struct Reference

`#include <IndexScalarQuantizer.h>`

Inheritance diagram for faiss::IndexIVFScalarQuantizer:

## Public Member Functions
| IndexIVFScalarQuantizer (Index *quantizer, size_t d, size_t nlist, ScalarQuantizer::QuantizerType qtype, MetricType metric=METRIC_L2)
void | train_residual (idx_t n, const float *x) override
void | add_with_ids (idx_t n, const float *x, const long *xids) override
void | search_preassigned (idx_t n, const float *x, idx_t k, const idx_t *assign, const float *centroid_dis, float *distances, idx_t *labels, bool store_pairs) const override
void | reconstruct_from_offset (long list_no, long offset, float *recons) const override
Public Member Functions inherited from faiss::IndexIVF
| IndexIVF (Index *quantizer, size_t d, size_t nlist, MetricType metric=METRIC_L2)
void | reset () override
| removes all elements from the database.
void | train (idx_t n, const float *x) override
| Trains the quantizer and calls train_residual to train sub-quantizers.
void | add (idx_t n, const float *x) override
| Quantizes x and calls add_with_key.
virtual void | search (idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const override
void | reconstruct (idx_t key, float *recons) const override
void | reconstruct_n (idx_t i0, idx_t ni, float *recons) const override
void | search_and_reconstruct (idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, float *recons) const override
long | remove_ids (const IDSelector &sel) override
| Dataset manipulation functions.
virtual void | merge_from (IndexIVF &other, idx_t add_id)
virtual void | copy_subset_to (IndexIVF &other, int subset_type, long a1, long a2) const
size_t | get_list_size (size_t list_no) const
void | make_direct_map (bool new_maintain_direct_map=true)
double | imbalance_factor () const
| 1= perfectly balanced, >1: imbalanced
void | print_stats () const
| display some stats about the inverted lists
Public Member Functions inherited from faiss::Index
| Index (idx_t d=0, MetricType metric=METRIC_L2)
virtual void | range_search (idx_t n, const float *x, float radius, RangeSearchResult *result) const
void | assign (idx_t n, const float *x, idx_t *labels, idx_t k=1)
void | compute_residual (const float *x, float *residual, idx_t key) const
void | display () const
Public Member Functions inherited from faiss::Level1Quantizer
void | train_q1 (size_t n, const float *x, bool verbose, MetricType metric_type)
| Trains the quantizer and calls train_residual to train sub-quantizers.
| Level1Quantizer (Index *quantizer, size_t nlist)

## Public Attributes
ScalarQuantizer | sq
Public Attributes inherited from faiss::IndexIVF
size_t | nprobe
| number of probes at query time
size_t | max_codes
| max nb of codes to visit to do a query
std::vector< std::vector< long > > | ids
| Inverted lists for indexes.
size_t | code_size
| code size per vector in bytes
std::vector< std::vector < uint8_t > > | codes
bool | maintain_direct_map
| map for direct access to the elements. Enables reconstruct().
std::vector< long > | direct_map
Public Attributes inherited from faiss::Index
int | d
| vector dimension
idx_t | ntotal
| total nb of indexed vectors
bool | verbose
| verbosity level
bool | is_trained
| set if the Index does not require training, or if training is done already
MetricType | metric_type
| type of metric this index uses for search
Public Attributes inherited from faiss::Level1Quantizer
Index * | quantizer
| quantizer that maps vectors to inverted lists
size_t | nlist
| number of possible key values
char | quantizer_trains_alone
bool | own_fields
| whether object owns the quantizer
ClusteringParameters | cp
| to override default clustering params
Index * | clustering_index
| to override index used during clustering

## Additional Inherited Members
Public Types inherited from faiss::Index
typedef long | idx_t
| all indices are this type

## Detailed Description

An IVF implementation where the components of the residuals are encoded with a scalar uniform quantizer. All distance computations are asymmetric, so the encoded vectors are decoded and approximate distances are computed.

Definition at line 146 of file IndexScalarQuantizer.h.

## Member Function Documentation

void faiss::IndexIVFScalarQuantizer::add_with_ids | ( | idx_t | n,
|  | const float * | x,
|  | const long * | xids
| ) |  |
| override virtual

Same as add, but stores xids instead of sequential ids.

The default implementation fails with an assertion, as it is not supported by all indexes.

Parameters

  xids | if non-null, ids to store for the vectors (size n)

Reimplemented from faiss::Index.

Definition at line 944 of file IndexScalarQuantizer.cpp.

void faiss::IndexIVFScalarQuantizer::reconstruct_from_offset | ( | long | list_no,
|  | long | offset,
|  | float * | recons
| ) |  | const
| override virtual

Reconstruct a vector given the location in terms of (inv list index + inv list offset) instead of the id.

Useful for reconstructing when the direct_map is not maintained and the inv list offset is computed by search_preassigned() with `store_pairs` set.

Reimplemented from faiss::IndexIVF.

Definition at line 1113 of file IndexScalarQuantizer.cpp.

void faiss::IndexIVFScalarQuantizer::search_preassigned | ( | idx_t | n,
|  | const float * | x,
|  | idx_t | k,
|  | const idx_t * | assign,
|  | const float * | centroid_dis,
|  | float * | distances,
|  | idx_t * | labels,
|  | bool | store_pairs
| ) |  | const
| override virtual

search a set of vectors, that are pre-quantized by the IVF quantizer. Fill in the corresponding heaps with the query results. search() calls this.

Parameters

  n | nb of vectors to query
  x | query vectors, size nx * d
  assign | coarse quantization indices, size nx * nprobe
  centroid_dis | distances to coarse centroids, size nx * nprobe
  distance | output distances, size n * k
  labels | output labels, size n * k
  store_pairs | store inv list index + inv list offset instead in upper/lower 32 bit of result, instead of ids (used for reranking).

Implements faiss::IndexIVF.

Definition at line 1073 of file IndexScalarQuantizer.cpp.

void faiss::IndexIVFScalarQuantizer::train_residual | ( | idx_t | n,
|  | const float * | x
| ) |  |
| override virtual

Sub-classes that encode the residuals can train their encoders here does nothing by default

Reimplemented from faiss::IndexIVF.

Definition at line 925 of file IndexScalarQuantizer.cpp.

The documentation for this struct was generated from the following files:

- /data/users/matthijs/github_faiss/faiss/IndexScalarQuantizer.h
- /data/users/matthijs/github_faiss/faiss/IndexScalarQuantizer.cpp