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udf_weightedavg.cc
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udf_weightedavg.cc
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/*
returns the weighted average of values
input parameters:
data (real)
weight (real)
number of decimals in result (int, optional)
output:
weighted of the values (real)
registering the function:
CREATE AGGREGATE FUNCTION weightedavg RETURNS REAL SONAME 'udf_weightedavg.so';
getting rid of the function:
DROP FUNCTION weightedavg;
*/
#ifdef STANDARD
#include <stdio.h>
#include <string.h>
#ifdef __WIN__
typedef unsigned __int64 ulonglong;
typedef __int64 longlong;
#else
typedef unsigned long long ulonglong;
typedef long long longlong;
#endif /*__WIN__*/
#else
#include <my_global.h>
#include <my_sys.h>
#endif
#include <mysql.h>
#include <m_ctype.h>
#include <m_string.h>
#ifdef HAVE_DLOPEN
extern "C" {
my_bool weightedavg_init( UDF_INIT* initid, UDF_ARGS* args, char* message );
void weightedavg_deinit( UDF_INIT* initid );
void weightedavg_clear( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char* is_error );
void weightedavg_reset( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
void weightedavg_add( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
double weightedavg( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
}
struct weightedavg_data
{
unsigned long count;
double datasum;
double weightsum;
};
my_bool weightedavg_init( UDF_INIT* initid, UDF_ARGS* args, char* message )
{
if (args->arg_count < 2 || args->arg_count>3)
{
strcpy(message,"wrong number of arguments: weightedavg() requires two or three arguments");
return 1;
}
if (args->arg_type[0]!=REAL_RESULT)
{
strcpy(message,"weightedavg() requires a real as parameter 1");
return 1;
}
if (args->arg_type[1]!=REAL_RESULT)
{
strcpy(message,"weightedavg() requires a real as parameter 2");
return 1;
}
if (args->arg_count>2 && (args->arg_type[3]!=INT_RESULT))
{
strcpy(message,"weightedavg() requires an int as parameter 3");
return 1;
}
initid->decimals=2;
if (args->arg_count==3 && (*((ulong*)args->args[2])<=16))
{
initid->decimals=*((ulong*)args->args[2]);
}
weightedavg_data *buffer = new weightedavg_data;
buffer->count = 0;
buffer->datasum = 0;
buffer->weightsum = 0;
initid->maybe_null = 1;
initid->max_length = 32;
initid->ptr = (char*)buffer;
return 0;
}
void weightedavg_deinit( UDF_INIT* initid )
{
delete initid->ptr;
}
void weightedavg_clear( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char* is_error )
{
weightedavg_data *buffer = (weightedavg_data*)initid->ptr;
buffer->count = 0;
buffer->datasum = 0;
buffer->weightsum = 0;
*is_null = 0;
*is_error = 0;
}
void weightedavg_reset( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char* is_error )
{
weightedavg_clear( initid, args, is_null, is_error );
weightedavg_add( initid, args, is_null, is_error );
}
void weightedavg_add( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char* is_error )
{
if (args->args[0]!=NULL && args->args[1]!=NULL)
{
weightedavg_data *buffer = (weightedavg_data*)initid->ptr;
buffer->datasum+=(double) *((double*) args->args[0])*(double) *((double*) args->args[1]);
buffer->weightsum+=(double) *((double*) args->args[1]);
buffer->count++;
}
}
double weightedavg( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char* is_error )
{
weightedavg_data* buffer = (weightedavg_data*)initid->ptr;
if (buffer->count==0 || buffer->weightsum==0.0 || *is_error!=0)
{
*is_null = 1;
return 0.0;
}
*is_null=0;
return (double) buffer->datasum/buffer->weightsum;
}
#endif