# Faiss: faiss::IndexIVFFlat Struct Reference

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faiss::IndexIVFFlat Struct Reference

`#include <IndexIVFFlat.h>`

Inheritance diagram for faiss::IndexIVFFlat:

## Public Member Functions

| IndexIVFFlat (Index *quantizer, size_t d, size_t nlist_, MetricType=METRIC_L2)
virtual void | add_core (idx_t n, const float *x, const long *xids, const long *precomputed_idx)
| same as add_with_ids, with precomputed coarse quantizer
void | add_with_ids (idx_t n, const float *x, const long *xids) override
| implemented for all IndexIVF* classes
void | encode_vectors (idx_t n, const float *x, const idx_t *list_nos, uint8_t *codes) const override
InvertedListScanner * | get_InvertedListScanner (bool store_pairs) const override
| get a scanner for this index (store_pairs means ignore labels)
void | range_search (idx_t n, const float *x, float radius, RangeSearchResult *result) const override
virtual void | update_vectors (int nv, idx_t *idx, const float *v)
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, size_t code_size, 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
| Calls add_with_ids with NULL ids.
virtual void | train_residual (idx_t n, const float *x)
virtual 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 IVFSearchParameters *params=nullptr) const
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.
void | check_compatible_for_merge (const IndexIVF &other) const
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
void | replace_invlists (InvertedLists *il, bool own=false)
| replace the inverted lists, old one is deallocated if own_invlists
Public Member Functions inherited from faiss::Index
| Index (idx_t d=0, MetricType metric=METRIC_L2)
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)

## Additional Inherited Members

Public Types inherited from faiss::Index
typedef long | idx_t
| all indices are this type
Public Attributes inherited from faiss::IndexIVF
InvertedLists * | invlists
| Acess to the actual data.
bool | own_invlists
size_t | code_size
| code size per vector in bytes
size_t | nprobe
| number of probes at query time
size_t | max_codes
| max nb of codes to visit to do a query
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

## Detailed Description

Inverted file with stored vectors. Here the inverted file pre-selects the vectors to be searched, but they are not otherwise encoded, the code array just contains the raw float entries.

Definition at line 25 of file IndexIVFFlat.h.

## Member Function Documentation

void faiss::IndexIVFFlat::encode_vectors | ( | idx_t | n,
|  | const float * | x,
|  | const idx_t * | list_nos,
|  | uint8_t * | codes
| ) |  | const

overridevirtual

Encodes a set of vectors as they would appear in the inverted lists

Parameters

  list_nos | inverted list ids as returned by the quantizer (size n). -1s are ignored.
  codes | output codes, size n * code_size

Implements faiss::IndexIVF.

Definition at line 83 of file IndexIVFFlat.cpp.

void faiss::IndexIVFFlat::range_search | ( | idx_t | n,
|  | const float * | x,
|  | float | radius,
|  | RangeSearchResult * | result
| ) |  | const

overridevirtual

query n vectors of dimension d to the index.

return all vectors with distance < radius. Note that many indexes do not implement the range_search (only the k-NN search is mandatory).

Parameters

  x | input vectors to search, size n * d
  radius | search radius
  result | result table

Reimplemented from faiss::Index.

Reimplemented in faiss::IndexIVFFlatDedup.

Definition at line 171 of file IndexIVFFlat.cpp.

void faiss::IndexIVFFlat::reconstruct_from_offset | ( | long | list_no,
|  | long | offset,
|  | float * | recons
| ) |  | const

overridevirtual

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.

Reimplemented in faiss::IndexIVFFlatDedup.

Definition at line 259 of file IndexIVFFlat.cpp.

void faiss::IndexIVFFlat::update_vectors | ( | int | nv,
|  | idx_t * | idx,
|  | const float * | v
| ) |  |

virtual

Update a subset of vectors.

The index must have a direct_map

Parameters

  nv | nb of vectors to update
  idx | vector indices to update, size nv
  v | vectors of new values, size nv*d

Reimplemented in faiss::IndexIVFFlatDedup.

Definition at line 223 of file IndexIVFFlat.cpp.

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

- /tmp/faiss/IndexIVFFlat.h
- /tmp/faiss/IndexIVFFlat.cpp