Search with A Hash Index

We provide here the codes for search with a hash index (and a kNN graph). The codes are used in our paper A Revisit of Hashing Algorithms for Approximate Nearest Neighbor Search.

You need a hash index and a kmeans partition for search. Please use the matlab codes of various hashing algorithms to generate the hash index and a kmeans partition.

Benchmark data set

SIFT1M and GIST1M

The performance was tested without parallelism.

ANN search using hash index (quantization hamming ranking approach)

How To Complie

Go to the root directory of hashingSearch and make.

cd hashingSearch/
make

How To Use

You need a hash index and a kmeans partition for search. Please use the matlab codes of various hashing algorithms to generate the hash index and a kmeans partition.

ANN search with a hash index using quantization hamming ranking approach
```
  cd samples/
  ./ikhamming_search  data_file BaseCodeFile query_file QueryCodeFile partitionFile result_file codelen initsz nPartition querNN
```
Meaning of the parameters(from left to right):

data_file -- database points
BaseCodeFile -- e.g. LSHtableSIFT32b. (The actual binary code file is LSHtableSIFT32b_1, LSHtableSIFT32b_2, ..., the program will automatically load the required number of bits specified by the codelen parameter)
query_file -- sift query points
QueryCodeFile -- e.g. LSHquerySIFT32b. (The actual binary code file is LSHquerySIFT32b_1, LSHquerySIFT32b_2, ..., the program will automatically load the required number of bits specified by the codelen parameter)
partitionFile -- a partition of the dataset, can be generated by kmeans (please see our matlab code for the format)
result_file -- path to save ANN search results of given query
codelen -- code length of the binary codes. (A long code will be split as multiple 32-bits tables for convenience)
initsz -- initial pool size, the parameter L in the paper
nPartition -- specify the number of nearest partitions to be examined. (these two parameters "initsz" and "nPartition" should grow at the same time. Actually, there is an optimal mapping between them)
querNN -- required number of returned neighbors (i.e. k of k-NN)
ANN search with a hash index using hamming ranking approach
```
  cd samples/
  ./hamming_search  data_file BaseCodeFile query_file QueryCodeFile result_file codelen initsz querNN
```
Meaning of the parameters(from left to right):

data_file -- database points
BaseCodeFile -- e.g. LSHtableSIFT32b. (The actual binary code file is LSHtableSIFT32b_1, LSHtableSIFT32b_2, ..., the program will automatically load the required number of bits specified by the codelen parameter)
query_file -- sift query points
QueryCodeFile -- e.g. LSHquerySIFT32b. (The actual binary code file is LSHquerySIFT32b_1, LSHquerySIFT32b_2, ..., the program will automatically load the required number of bits specified by the codelen parameter)
result_file -- path to save ANN search results of given query
codelen -- code length of the binary codes. (A long code will be split as multiple 32-bits tables for convenience)
initsz -- initial pool size, the parameter L in the paper
querNN -- required number of returned neighbors (i.e. k of k-NN)
ANN search with a hash index using hash bucket search approach
```
  cd samples/
  ./hashing_search data_file BaseCodeFile query_file QueryCodeFile result_file tablelen codelen initsz querNN 
```
Meaning of the parameters(from left to right):

data_file -- database points
BaseCodeFile -- e.g. LSHtableSIFT32b. (The actual binary code file is LSHtableSIFT32b_1, LSHtableSIFT32b_2, ..., the program will automatically load the required number of bits specified by the codelen parameter)
query_file -- sift query points
QueryCodeFile -- e.g. LSHquerySIFT32b. (The actual binary code file is LSHquerySIFT32b_1, LSHquerySIFT32b_2, ..., the program will automatically load the required number of bits specified by the codelen parameter)
result_file -- path to save ANN search results of given query
tablelen -- table length. (A long code will be stored in multiple tables for effeciency. Please see our paper for details. ) The maximum tablelen is 64.
codelen -- code length of the binary codes. (A long code will be split as multiple 32-bits tables for convenience)
initsz -- initial pool size, the parameter L in the paper
querNN -- required number of returned neighbors (i.e. k of k-NN)

Output and Input format

Same as that of EFANNA

nicoledjy / hashingSearch