[postgis-users] ST_SelectByValue

[Pierre Racine]

Try ST_Reclass().

> -----Original Message-----
> From: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-
> bounces at lists.osgeo.org] On Behalf Of David Haynes
> Sent: Friday, May 30, 2014 10:49 AM
> To: postgis-users at lists.osgeo.org
> Subject: [postgis-users] ST_SelectByValue
> 
> Hello,
> 
> I am fairly new to using rasters in postgis, but I am wondering if there is a
> faster way to extract values from categorical rasters (e.g. landcover types)
> than using map algebra. In the PostGIS in Action book, pg 404 has a
> function called ST_SelectByValue(raster|geometry, 'expression') which
> seems to incorporate map algebra, however I can't seem to tell if this
> function is finished and available in postgis as I get an unknown function
> error.
> 
> My version is this.
> "PostgreSQL 9.3.2 on x86_64-unknown-linux-gnu, compiled by gcc
> (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3, 64-bit POSTGIS="2.1.1 r12113"
> GEOS="3.3.3-CAPI-1.7.4" PROJ="Rel. 4.7.1, 23 September 2009"
> GDAL="GDAL 1.9.0, released 2011/12/29" LIBXML="2.7.8" LIBJSON="UN
> (...)"
> 
> 
> And I found a webpage
> http://trac.osgeo.org/postgis/wiki/WKTRaster/SpecificationWorking03
> 
> search for "ST_SelectByValue" at the bottom, indicating that it was finished.
> 
> 
> AAccomplished Objectives
> <http://trac.osgeo.org/postgis/wiki/WKTRaster/SpecificationWorking03#A
> ccomplishedObjectives>
> 
> 
> ST_ValueCount(raster, value) -> integer - done see below
> 
> ST_ValuePercent(raster, value) -> double precision - done see below
> 
> ST_Resample(raster, method, originx, originy, pixelsizex, pixelsizey) -> raster
> - done see below
> 
> ST_SelectByValue(raster, 'expression') -> same type as first argument
> 
> ST_Clip(raster|geometry,geometry) -> same type as first argument