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70 lines
1.3 KiB
C
70 lines
1.3 KiB
C
#include "postgres.h"
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#include "bitutils.h"
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#include "bitvec.h"
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#include "utils/varbit.h"
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#include "vector.h"
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#if PG_VERSION_NUM >= 160000
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#include "varatt.h"
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#endif
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/*
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* Allocate and initialize a new bit vector
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*/
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VarBit *
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InitBitVector(int dim)
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{
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VarBit *result;
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int size;
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size = VARBITTOTALLEN(dim);
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result = (VarBit *) palloc0(size);
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SET_VARSIZE(result, size);
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VARBITLEN(result) = dim;
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return result;
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}
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/*
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* Ensure same dimensions
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*/
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static inline void
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CheckDims(VarBit *a, VarBit *b)
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{
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if (VARBITLEN(a) != VARBITLEN(b))
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ereport(ERROR,
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(errcode(ERRCODE_DATA_EXCEPTION),
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errmsg("different bit lengths %u and %u", VARBITLEN(a), VARBITLEN(b))));
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}
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/*
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* Get the Hamming distance between two bit vectors
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*/
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FUNCTION_PREFIX PG_FUNCTION_INFO_V1(hamming_distance);
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Datum
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hamming_distance(PG_FUNCTION_ARGS)
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{
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VarBit *a = PG_GETARG_VARBIT_P(0);
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VarBit *b = PG_GETARG_VARBIT_P(1);
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CheckDims(a, b);
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PG_RETURN_FLOAT8((double) BitHammingDistance(VARBITBYTES(a), VARBITS(a), VARBITS(b), 0));
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}
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/*
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* Get the Jaccard distance between two bit vectors
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*/
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FUNCTION_PREFIX PG_FUNCTION_INFO_V1(jaccard_distance);
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Datum
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jaccard_distance(PG_FUNCTION_ARGS)
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{
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VarBit *a = PG_GETARG_VARBIT_P(0);
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VarBit *b = PG_GETARG_VARBIT_P(1);
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CheckDims(a, b);
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PG_RETURN_FLOAT8(BitJaccardDistance(VARBITBYTES(a), VARBITS(a), VARBITS(b), 0, 0, 0));
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}
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