id summary reporter owner description type status priority milestone component version resolution keywords cc 930 [raster] ST_SummaryStats Bborie Park Bborie Park "Like how ST_AsGDALRaster is the backend to ST_AsTIFF, ST_AsJPEG and ST_AsPNG, ST_SummaryStats is the backend for several summary stats: 1. Count of the population/sample included in the stats 2. Mean (ST_Mean or is ST_Average better?) 3. Standard Deviation (ST_StdDev) 4. !Min/Max (ST_MinMax) The proposed variations are: 1. ST_SummaryStats(rast raster, nband int, ignore_nodata boolean) -> record returns one record of five columns (count, mean, stddev, min, max) nband: index of band to process on ignore_nodata: if TRUE, any pixel who's value is nodata is ignored. {{{ ST_SummaryStats(rast, 2, TRUE) }}} 2. ST_SummaryStats(rast raster, nband int) -> record assumes ignore_nodata = TRUE {{{ ST_SummaryStats(rast, 2) }}} 3. ST_SummaryStats(rast raster, ignore_nodata boolean) -> record assumes band index = 1 {{{ ST_SummaryStats(rast, FALSE) }}} 4. ST_SummaryStats(rast raster) -> record assumes band index = 1 and ignore_nodata = TRUE {{{ ST_SummaryStats(rast) }}} Four approximation functions are also proposed sacrificing some accuracy for speed, especially on large rasters (10000 x 10000). 1. ST_SummaryStats(rast raster, nband int, ignore_nodata boolean, sample_percent double precision) -> record sample_percent: a value between 0 and 1 indicating the percentage of the raster band's pixels to consider when determining the min/max pair. {{{ ST_SummaryStats(rast, 3, FALSE, 0.1) ST_SummaryStats(rast, 1, TRUE, 0.5) }}} 2. ST_SummaryStats(rast raster, ignore_nodata boolean, sample_percent double precision) -> record assumes that nband = 1 {{{ ST_SummaryStats(rast, FALSE, 0.01) ST_SummaryStats(rast, TRUE, 0.025) }}} 3. ST_SummaryStats(rast raster, sample_percent double precision) -> record assumes that nband = 1 and ignore_nodata = TRUE {{{ ST_SummaryStats(rast, 0.25) }}} 4. ST_SummaryStats(rast raster) -> record assumes that nband = 1, ignore_nodata = TRUE and sample_percent = 0.1 {{{ ST_SummaryStats(rast) }}} New tickets for ST_Mean and ST_StdDev will be posted next. Functions that can depend upon the basic stats (ST_Histogram and ST_Quantile) will be proposed later." task closed medium PostGIS 2.0.0 raster master fixed history