Initialize

API Definition

Status ScannInterface::Initialize(ConstSpan<float> dataset, DatapointIndex n_points, const std::string& config, int training_threads);

Function

Index construction (consistent with the open source algorithm).

Parameters

Parameter	Data Type	Description	Value Range
dataset	ConstSpan<float>	Base library vector.	The value cannot be null.
n_points	DatapointIndex	Number of vectors in the base library.	The length must be the same as that of dataset. dataset indicates the base library vector.
config	const std::string&	Configuration file required for creating the index, containing all configuration parameters.	-
training_threads	int	Number of threads during query construction.	≥ 1

config is generated by the create_config.py script in combination with the following parameters.

Parameter	Data Type	Description	Value Range
n_leaves	int	Total subspace number in the IVF partition.	≥ 1
nb	int32_t	Number of vectors in the base library.	The length must be the same as that of dataset. dataset indicates the base library vector.
metricType	std::string	Distance type of the vector.	dot_product or squared_l2.
dims_per_block	int	Number of dimensions combined by PQ.	[1,dim], where dim indicates the dimension of the base library vector.
avq_threshold	float	Asymmetric bucket parameter. This parameter takes effect only for the L2 (squared_l2) dataset.	[0, 1]
dim	int32_t	Dimensions of vectors in the base library.	The dimensions must be the same as those of dataset. dataset indicates the base library vector.
topK	int	Number of returned results.	≥ 1
soar_lambda	float	Controls orthogonality. This parameter takes effect only for the IP (dot product) dataset.	> 0. If the value is to -1, the function is disabled.
overretrieve_factor	float	Used together with soar_lambda to specify the over-retrieval factor. This parameter takes effect only for the IP (dot_product) dataset.	[1, 2]. If the value is to -1, the function is disabled.

config is generated by create_config.py. The command is as follows:

python create_config.py  + std::to_string(n_leaves) + " "
                         + std::to_string(nb) + " "
                         + metricType + " "
                         + std::to_string(dims_per_block) + " "
                         + std::to_string(avq_threshold) + " "
                         + std::to_string(dim) + " "
                         + std::to_string(topK) + " "
                         + std::to_string(soar_lambda) + " "
                         + std::to_string(overretrieve_factor)

Return Value

Data Type	Description
Status	Execution status of the method. You can determine whether the method is successfully executed by calling status.ok().

Parent topic: C++ APIs