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Added l1_distance function for sparsevec [skip ci]

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Andrew Kane
2024-04-14 22:59:28 -07:00
parent b70fb2b3f4
commit 4f6c4850d9
5 changed files with 80 additions and 0 deletions
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3
sql/vector--0.6.2--0.7.0.sql
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@@ -344,6 +344,9 @@ CREATE FUNCTION inner_product(sparsevec, sparsevec) RETURNS float8
CREATE FUNCTION cosine_distance(sparsevec, sparsevec) RETURNS float8
AS 'MODULE_PATHNAME', 'sparsevec_cosine_distance' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
CREATE FUNCTION l1_distance(sparsevec, sparsevec) RETURNS float8
AS 'MODULE_PATHNAME', 'sparsevec_l1_distance' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
CREATE FUNCTION l2_norm(sparsevec) RETURNS float8
AS 'MODULE_PATHNAME', 'sparsevec_l2_norm' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

3
sql/vector.sql
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@@ -653,6 +653,9 @@ CREATE FUNCTION inner_product(sparsevec, sparsevec) RETURNS float8
CREATE FUNCTION cosine_distance(sparsevec, sparsevec) RETURNS float8
AS 'MODULE_PATHNAME', 'sparsevec_cosine_distance' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
CREATE FUNCTION l1_distance(sparsevec, sparsevec) RETURNS float8
AS 'MODULE_PATHNAME', 'sparsevec_l1_distance' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
CREATE FUNCTION l2_norm(sparsevec) RETURNS float8
AS 'MODULE_PATHNAME', 'sparsevec_l2_norm' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

49
src/sparsevec.c
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@@ -781,6 +781,55 @@ sparsevec_cosine_distance(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT8(1.0 - similarity);
}
/*
* Get the L1 distance between two sparse vectors
*/
PGDLLEXPORT PG_FUNCTION_INFO_V1(sparsevec_l1_distance);
Datum
sparsevec_l1_distance(PG_FUNCTION_ARGS)
{
SparseVector *a = PG_GETARG_SPARSEVEC_P(0);
SparseVector *b = PG_GETARG_SPARSEVEC_P(1);
float *ax = SPARSEVEC_VALUES(a);
float *bx = SPARSEVEC_VALUES(b);
double distance = 0.0;
int bpos = 0;
CheckDims(a, b);
for (int i = 0; i < a->nnz; i++)
{
int ai = a->indices[i];
int bi = -1;
for (int j = bpos; j < b->nnz; j++)
{
bi = b->indices[j];
if (ai == bi)
distance += fabs(ax[i] - bx[j]);
else if (ai > bi)
distance += fabs(bx[j]);
/* Update start for next iteration */
if (ai >= bi)
bpos = j + 1;
/* Found or passed it */
if (bi >= ai)
break;
}
if (ai != bi)
distance += fabs(ax[i]);
}
for (int j = bpos; j < b->nnz; j++)
distance += fabs(bx[j]);
PG_RETURN_FLOAT8(distance);
}
/*
* Get the L2 norm of a sparse vector
*/

20
test/expected/sparsevec_functions.out
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@@ -198,3 +198,23 @@ SELECT cosine_distance('{}/1'::sparsevec, '{}/1');
SELECT cosine_distance('{1:2}/2'::sparsevec, '{1:1}/3');
ERROR: different sparsevec dimensions 2 and 3
SELECT l1_distance('{}/2'::sparsevec, '{1:3,2:4}/2');
l1_distance
-------------
7
(1 row)
SELECT l1_distance('{}/2'::sparsevec, '{2:1}/2');
l1_distance
-------------
1
(1 row)
SELECT l1_distance('{1:1,2:2}/2'::sparsevec, '{1:3}/1');
ERROR: different sparsevec dimensions 2 and 1
SELECT l1_distance('{1:3e38}/1'::sparsevec, '{1:-3e38}/1');
l1_distance
-------------
Infinity
(1 row)

5
test/sql/sparsevec_functions.sql
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@@ -37,3 +37,8 @@ SELECT cosine_distance('{1:1,2:1}/2'::sparsevec, '{1:-1,2:-1}/2');
SELECT cosine_distance('{1:2}/2'::sparsevec, '{2:2}/2');
SELECT cosine_distance('{}/1'::sparsevec, '{}/1');
SELECT cosine_distance('{1:2}/2'::sparsevec, '{1:1}/3');
SELECT l1_distance('{}/2'::sparsevec, '{1:3,2:4}/2');
SELECT l1_distance('{}/2'::sparsevec, '{2:1}/2');
SELECT l1_distance('{1:1,2:2}/2'::sparsevec, '{1:3}/1');
SELECT l1_distance('{1:3e38}/1'::sparsevec, '{1:-3e38}/1');