[postgis-devel] [PostGIS] #953: [raster] ST_Count

[PostGIS]

#953: [raster] ST_Count
----------------------------+-----------------------------------------------
 Reporter:  dustymugs       |       Owner:  dustymugs            
     Type:  task            |      Status:  new                  
 Priority:  medium          |   Milestone:  PostGIS Raster Future
Component:  postgis raster  |     Version:  trunk                
 Keywords:                  |  
----------------------------+-----------------------------------------------
 ST_Count provides the ability to count the number of times that a user-
 provided value is present in a raster.  To handle floating point values, a
 rounding argument is provided.

 1. ST_Count(rast raster, nband integer, hasnodata boolean, value double
 precision, roundto double precision) -> integer

   returns the number of times that value is present in the raster

   hasnodata: if FALSE, nodata values in band are considered in the count.
 if TRUE, nodata values are not considered

   value: the value to count in the raster

   roundto: the decimal position to round a pixel value to.  Originally
 intended for use with 32BF and 64BF pixel types, it can also be used with
 integers when round to the tens, hundreds or higher place.

     examples are...
 {{{
 roundto < 0: no rounding

 0: no rounding

 0.1: round to the tenths place

 0.01: round to the hundredths place

 0.001: round to the thousandths place

 1: round to the ones place

 10: round to the tens place

 100: round to the hundreds place
 }}}

 {{{
 ST_Count(rast, 1, TRUE, 23, 0)

 ST_Count(rast, 5, FALSE, 3.14, 0.01)

 ST_Count(rast, 2, TRUE, 100, 100)

 ST_Count(rast, 1, FALSE, -9999, 1)
 }}}

 2. ST_Count(rast raster, nband integer, value double precision, roundto
 double precision) -> integer

   hasnodata is assumed to be TRUE

 {{{
 ST_Count(rast, 5, 3.14, 0.01)

 ST_Count(rast, 2, 100, 100)
 }}}

 3. ST_Count(rast raster, nband integer, value double precision) -> integer

   roundto is assumed to be 0, so no rounding takes place. hasnodata is
 assumed to be TRUE

 {{{
 ST_Count(rast, 1, -9999)
 }}}

 4. ST_Count(rast raster, value double precision, roundto double precision)
 -> integer

   nband is assumed to be 1. hasnodata is assumed to be TRUE.

 5. ST_Count(rast raster, value double precision) -> integer

   nband is assumed to be 1. roundto is assumed to be 0, so no rounding
 takes place. hasnodata is assumed to be TRUE.

 A set of variations where more than one value parameter can be provided
 should be added.

 A set of variations where no value parameter is provided should be added.
 This results in every unique value is counted, unless a roundto parameter
 is provided.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/953>
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