RASTER_summaryStats()

Datum RASTER_summaryStats

(

PG_FUNCTION_ARGS

)

Definition at line 73 of file rtpg_statistics.c.

{
        rt_pgraster *pgraster = NULL;
        rt_raster raster = NULL;
        rt_band band = NULL;
        int32_t bandindex = 1;
        bool exclude_nodata_value = TRUE;
        int num_bands = 0;
        double sample = 0;
        rt_bandstats stats = NULL;
 
        TupleDesc tupdesc;
        Datum values[VALUES_LENGTH];
        bool nulls[VALUES_LENGTH];
        HeapTuple tuple;
        Datum result;
 
        /* pgraster is null, return null */
        if (PG_ARGISNULL(0))
                PG_RETURN_NULL();
        pgraster = (rt_pgraster *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
 
        raster = rt_raster_deserialize(pgraster, FALSE);
        if (!raster) {
                PG_FREE_IF_COPY(pgraster, 0);
                elog(ERROR, "RASTER_summaryStats: Cannot deserialize raster");
                PG_RETURN_NULL();
        }
 
        /* band index is 1-based */
        if (!PG_ARGISNULL(1))
                bandindex = PG_GETARG_INT32(1);
        num_bands = rt_raster_get_num_bands(raster);
        if (bandindex < 1 || bandindex > num_bands) {
                elog(NOTICE, "Invalid band index (must use 1-based). Returning NULL");
                rt_raster_destroy(raster);
                PG_FREE_IF_COPY(pgraster, 0);
                PG_RETURN_NULL();
        }
 
        /* exclude_nodata_value flag */
        if (!PG_ARGISNULL(2))
                exclude_nodata_value = PG_GETARG_BOOL(2);
 
        /* sample % */
        if (!PG_ARGISNULL(3)) {
                sample = PG_GETARG_FLOAT8(3);
                if (sample < 0 || sample > 1) {
                        elog(NOTICE, "Invalid sample percentage (must be between 0 and 1). Returning NULL");
                        rt_raster_destroy(raster);
                        PG_FREE_IF_COPY(pgraster, 0);
                        PG_RETURN_NULL();
                }
                else if (FLT_EQ(sample, 0.0))
                        sample = 1;
        }
        else
                sample = 1;
 
        /* get band */
        band = rt_raster_get_band(raster, bandindex - 1);
        if (!band) {
                elog(NOTICE, "Cannot find band at index %d. Returning NULL", bandindex);
                rt_raster_destroy(raster);
                PG_FREE_IF_COPY(pgraster, 0);
                PG_RETURN_NULL();
        }
 
        /* we don't need the raw values, hence the zero parameter */
        stats = rt_band_get_summary_stats(band, (int) exclude_nodata_value, sample, 0, NULL, NULL, NULL);
        rt_band_destroy(band);
        rt_raster_destroy(raster);
        PG_FREE_IF_COPY(pgraster, 0);
        if (NULL == stats) {
                elog(NOTICE, "Cannot compute summary statistics for band at index %d. Returning NULL", bandindex);
                PG_RETURN_NULL();
        }
 
        /* Build a tuple descriptor for our result type */
        if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) {
                ereport(ERROR, (
                        errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                        errmsg(
                                "function returning record called in context "
                                "that cannot accept type record"
                        )
                ));
        }
 
        BlessTupleDesc(tupdesc);
 
        memset(nulls, FALSE, sizeof(bool) * VALUES_LENGTH);
 
        values[0] = Int64GetDatum(stats->count);
        if (stats->count > 0) {
                values[1] = Float8GetDatum(stats->sum);
                values[2] = Float8GetDatum(stats->mean);
                values[3] = Float8GetDatum(stats->stddev);
                values[4] = Float8GetDatum(stats->min);
                values[5] = Float8GetDatum(stats->max);
        }
        else {
                nulls[1] = TRUE;
                nulls[2] = TRUE;
                nulls[3] = TRUE;
                nulls[4] = TRUE;
                nulls[5] = TRUE;
        }
 
        /* build a tuple */
        tuple = heap_form_tuple(tupdesc, values, nulls);
 
        /* make the tuple into a datum */
        result = HeapTupleGetDatum(tuple);
 
        /* clean up */
        pfree(stats);
 
        PG_RETURN_DATUM(result);
}

References rt_bandstats_t::count, FALSE, FLT_EQ, rt_bandstats_t::max, rt_bandstats_t::mean, rt_bandstats_t::min, rt_band_destroy(), rt_band_get_summary_stats(), rt_raster_deserialize(), rt_raster_destroy(), rt_raster_get_band(), rt_raster_get_num_bands(), rt_bandstats_t::stddev, rt_bandstats_t::sum, TRUE, and VALUES_LENGTH.

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