id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc 935,[raster] ST_Quantile and ST_ApproxQuantile,Bborie Park,Bborie Park,"In addition to determining the histogram of a raster, providing the ability to compute quantiles permits a user to reference a value in the context of the sample or population. Thus, a value could be examined to be at the raster's 25%, 50%, 75% percentile. http://en.wikipedia.org/wiki/Quantile ST_Quantile variations: 1. ST_Quantile(rast raster, nband int, hasnodata boolean, quantiles double precision[]) -> set of records nband: index of band to process on hasnodata: if FALSE, any pixel who's value is nodata is ignored. quantiles: array of percentages to compute values for {{{ ST_Quantile(rast, 1, FALSE, ARRAY[0.1, 0.3, 0.7]) ST_Quantile(rast, 1, TRUE, ARRAY[0.2]) ST_Quantile(rast, 1, FALSE, ARRAY[0, 1]) }}} 2. ST_Quantile(rast raster, nband int, quantiles double precision[]) -> set of records ""hasnodata"" is assumed to be FALSE {{{ ST_Quantile(rast, 1, ARRAY[0.1, 0.3, 0.7]) }}} 3. ST_Quantile(rast raster, nband int, hasnodata boolean) -> set of records ""quantiles"" assumed to be ARRAY[0, 0.25, 0.5, 0.75, 1] 4. ST_Quantile(rast raster, nband int) -> set of records ""hasnodata"" is assumed to be FALSE and ""quantiles"" assumed to be ARRAY[0, 0.25, 0.5, 0.75, 1] 5. ST_Quantile(rast raster, quantiles double precision[]) -> set of records ""nband"" is assumed to be 1 and ""hasnodata"" is FALSE 6. ST_Quantile(rast raster, nband int, quantile double precision) -> record quantile: the single percentile to compute 7. ST_Quantile(rast raster, quantile double precision) -> record ""nband"" is assumed to be 1 8. ST_Quantile(rast raster) -> set of records ""nband"" is assumed to be 1 and ""quantiles"" assumed to be ARRAY[0, 0.25, 0.5, 0.75, 1] ST_ApproxQuantile adds a ""sample_percent"" indicating the percentage of the raster to sample 1. ST_ApproxQuantile(rast raster, nband int, hasnodata boolean, sample_percent double precision, quantiles double precision[]) -> set of records nband: index of band to process on hasnodata: if FALSE, any pixel who's value is nodata is ignored sample_percent: a value between 0 and 1 indicating the percentage of the raster band's pixels to consider when computing the quantiles quantiles: array of percentages to compute values for {{{ ST_ApproxQuantile(rast, 1, FALSE, 0.1, ARRAY[0.1, 0.3, 0.7]) ST_ApproxQuantile(rast, 1, TRUE, .2, ARRAY[0.2]) ST_ApproxQuantile(rast, 1, FALSE, 0.3, ARRAY[0, 1]) }}} 2. ST_ApproxQuantile(rast raster, nband int, sample_percent double precision, quantiles double precision[]) -> set of records ""hasnodata"" is assumed to be FALSE {{{ ST_ApproxQuantile(rast, 1, .05, ARRAY[0.1, 0.3, 0.7]) }}} 3. ST_ApproxQuantile(rast raster, nband int, sample_percent double precision) -> set of records ""hasnodata"" is assumed to be FALSE and ""quantiles"" assumed to be ARRAY[0, 0.25, 0.5, 0.75, 1] 4. ST_ApproxQuantile(rast raster, sample_percent double precision, quantiles double precision[]) -> set of records ""nband"" is assumed to be 1 5. ST_ApproxQuantile(rast raster, nband int, sample_percent double precision, quantile double precision) -> record quantile: the single percentile to compute 6. ST_ApproxQuantile(rast raster, sample_percent double precision, quantile double precision) -> record ""nband"" is assumed to be 2 7. ST_ApproxQuantile(rast raster, sample_percent double precision) -> set of records ""nband"" is assumed to be 1 and ""quantiles"" assumed to be ARRAY[0, 0.25, 0.5, 0.75, 1] 8. ST_ApproxQuantile(rast raster, nband int, quantile double precision) -> record ""sample_percent"" assumed to be 0.1 9. ST_ApproxQuantile(rast raster, quantiles double precision[]) -> set of records ""nband"" is assumed to be 1 and ""sample_percent"" assumed to be 0.1 10. ST_ApproxQuantile(rast raster, quantile double precision) -> record ""nband"" assumed to be 1 and ""sample_percent"" assumed to be 0.1 11. ST_ApproxQuantile(rast raster, nband int) -> set of records ""quantiles"" assumed to be ARRAY[0, 0.25, 0.5, 0.75, 1] and ""sample_percent"" assumed to be 0.1 12. ST_ApproxQuantile(rast raster) -> set of records ""nband"" is assumed to be 1, ""quantiles"" assumed to be ARRAY[0, 0.25, 0.5, 0.75, 1] and ""sample_percent"" assumed to be 0.1",task,closed,medium,PostGIS 2.0.0,raster,master,fixed,history,