Added avg aggregate for vector - closes #51

src/vector.c

@@ -23,6 +23,9 @@
 #define TYPALIGN_INT 'i'
 #endif
 
+#define STATE_DIMS(x) (ARR_DIMS(x)[0] - 1)
+#define CreateStateDatums(dim) palloc(sizeof(Datum) * (dim + 1))
+
 PG_MODULE_MAGIC;
 
 /*
@@ -82,6 +85,20 @@ CheckElement(float value)
 				 errmsg("infinite value not allowed in vector")));
 }
 
+/*
+ * Check state array
+ */
+static float8 *
+CheckStateArray(ArrayType *statearray, const char *caller)
+{
+	if (ARR_NDIM(statearray) != 1 ||
+		ARR_DIMS(statearray)[0] < 1 ||
+		ARR_HASNULL(statearray) ||
+		ARR_ELEMTYPE(statearray) != FLOAT8OID)
+		elog(ERROR, "%s: expected state array", caller);
+	return (float8 *) ARR_DATA_PTR(statearray);
+}
+
 /*
  * Print vector - useful for debugging
  */
@@ -758,3 +775,167 @@ vector_cmp(PG_FUNCTION_ARGS)
 
 	PG_RETURN_INT32(vector_cmp_internal(a, b));
 }
+
+/*
+ * Accumulate vectors
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(vector_accum);
+Datum
+vector_accum(PG_FUNCTION_ARGS)
+{
+	ArrayType  *statearray = PG_GETARG_ARRAYTYPE_P(0);
+	Vector	   *newval = PG_GETARG_VECTOR_P(1);
+	float8	   *statevalues;
+	int16		dim;
+	bool		newarr;
+	float8		n;
+	Datum	   *statedatums;
+	float	   *x = newval->x;
+	ArrayType  *result;
+
+	/* Check array before using */
+	statevalues = CheckStateArray(statearray, "vector_accum");
+	dim = STATE_DIMS(statearray);
+	newarr = dim == 0;
+
+	if (newarr)
+		dim = newval->dim;
+	else
+		CheckExpectedDim(dim, newval->dim);
+
+	n = statevalues[0] + 1.0;
+
+	statedatums = CreateStateDatums(dim);
+	statedatums[0] = Float8GetDatumFast(n);
+
+	if (newarr)
+	{
+		for (int i = 0; i < dim; i++)
+			statedatums[i + 1] = Float8GetDatumFast(x[i]);
+	}
+	else
+	{
+		for (int i = 0; i < dim; i++)
+		{
+			double		v = statevalues[i + 1] + x[i];
+
+			if (isinf(v))
+				float_overflow_error();
+
+			statedatums[i + 1] = Float8GetDatumFast(v);
+		}
+	}
+
+	/* Use float8 array like float4_accum */
+	result = construct_array(statedatums, dim + 1,
+							 FLOAT8OID,
+							 sizeof(float8), FLOAT8PASSBYVAL, TYPALIGN_DOUBLE);
+
+	pfree(statedatums);
+
+	PG_RETURN_ARRAYTYPE_P(result);
+}
+
+/*
+ * Combine vectors
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(vector_combine);
+Datum
+vector_combine(PG_FUNCTION_ARGS)
+{
+	ArrayType  *statearray1 = PG_GETARG_ARRAYTYPE_P(0);
+	ArrayType  *statearray2 = PG_GETARG_ARRAYTYPE_P(1);
+	float8	   *statevalues1;
+	float8	   *statevalues2;
+	float8		n;
+	float8		n1;
+	float8		n2;
+	int16		dim;
+	Datum	   *statedatums;
+	ArrayType  *result;
+
+	/* Check arrays before using */
+	statevalues1 = CheckStateArray(statearray1, "vector_combine");
+	statevalues2 = CheckStateArray(statearray2, "vector_combine");
+
+	n1 = statevalues1[0];
+	n2 = statevalues2[0];
+
+	if (n1 == 0.0)
+	{
+		n = n2;
+		dim = STATE_DIMS(statearray2);
+		statedatums = CreateStateDatums(dim);
+		for (int i = 1; i <= dim; i++)
+			statedatums[i] = Float8GetDatumFast(statevalues2[i]);
+	}
+	else if (n2 == 0.0)
+	{
+		n = n1;
+		dim = STATE_DIMS(statearray1);
+		statedatums = CreateStateDatums(dim);
+		for (int i = 1; i <= dim; i++)
+			statedatums[i] = Float8GetDatumFast(statevalues1[i]);
+	}
+	else
+	{
+		n = n1 + n2;
+		dim = STATE_DIMS(statearray1);
+		CheckExpectedDim(dim, STATE_DIMS(statearray2));
+		statedatums = CreateStateDatums(dim);
+		for (int i = 1; i <= dim; i++)
+		{
+			double		v = statevalues1[i] + statevalues2[i];
+
+			if (isinf(v))
+				float_overflow_error();
+
+			statedatums[i] = Float8GetDatumFast(v);
+		}
+	}
+
+	statedatums[0] = Float8GetDatumFast(n);
+
+	result = construct_array(statedatums, dim + 1,
+							 FLOAT8OID,
+							 sizeof(float8), FLOAT8PASSBYVAL, TYPALIGN_DOUBLE);
+
+	pfree(statedatums);
+
+	PG_RETURN_ARRAYTYPE_P(result);
+}
+
+/*
+ * Average vectors
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(vector_avg);
+Datum
+vector_avg(PG_FUNCTION_ARGS)
+{
+	ArrayType  *statearray = PG_GETARG_ARRAYTYPE_P(0);
+	float8	   *statevalues;
+	float8		n;
+	uint16		dim;
+	Vector	   *result;
+	float		v;
+
+	/* Check array before using */
+	statevalues = CheckStateArray(statearray, "vector_avg");
+	n = statevalues[0];
+
+	/* SQL defines AVG of no values to be NULL */
+	if (n == 0.0)
+		PG_RETURN_NULL();
+
+	/* Create vector */
+	dim = STATE_DIMS(statearray);
+	result = InitVector(dim);
+	for (int i = 0; i < dim; i++)
+	{
+		v = statevalues[i + 1] / n;
+		CheckElement(v);
+		result->x[i] = v;
+	}
+
+	PG_RETURN_POINTER(result);
+}