[postgis-devel] [PostGIS] #931: [raster] ST_Mean

[PostGIS]

#931: [raster] ST_Mean
----------------------------+-----------------------------------------------
 Reporter:  dustymugs       |       Owner:  dustymugs            
     Type:  task            |      Status:  assigned             
 Priority:  medium          |   Milestone:  PostGIS Raster Future
Component:  postgis raster  |     Version:  trunk                
 Keywords:                  |  
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Changes (by dustymugs):

  * status:  new => assigned


Comment:

 I've decided to go with your suggestion Pierre.

 {{{
 ST_Mean(rastertable text, rastercolumn text)
 }}}

 I realized as I was playing around with various possibilities that your
 way was the only way that a tile would be loaded one at a time and not
 overtly tax memory.

 So, a set of variations of ST_Mean and ST_ApproxMean for handling large
 sets of raster tiles:

 1. ST_Mean(rastertable text, rastercolumn text, nband int, hasnodata
 boolean) -> double precision

 {{{
 ST_Mean('tmax_2010', 'rast', 1, FALSE)

 ST_Mean('precip_2011', 'rast', 1, TRUE)
 }}}

 2. ST_Mean(rastertable text, rastercolumn text, nband int) -> double
 precision

   hasnodata is set to FALSE

 {{{
 ST_Mean('tmax_2010', 'rast', 1)
 }}}

 3. ST_Mean(rastertable text, rastercolumn text, hasnodata boolean) ->
 double precision

   nband is set to 1

 {{{
 ST_Mean('precip_2011', 'rast', TRUE)
 }}}

 4. ST_Mean(rastertable text, rastercolumn text) -> double precision

   nband is set to 1 and hasnodata is set to FALSE

 {{{
 ST_Mean('tmin_2009', 'rast')
 }}}

 Variations for ST_ApproxMean are:

 1. ST_ApproxMean(rastertable text, rastercolumn text, nband int, hasnodata
 boolean, sample_percent double precision) -> double precision

 {{{
 ST_ApproxMean('tmax_2010', 'rast', 1, FALSE, 0.5)

 ST_ApproxMean('precip_2011', 'rast', 1, TRUE, 0.2)
 }}}

 2. ST_ApproxMean(rastertable text, rastercolumn text, nband int,
 sample_percent double precision) -> double precision

   hasnodata is set to FALSE

 {{{
 ST_ApproxMean('tmax_2010', 'rast', 1, 0.5)

 ST_ApproxMean('precip_2011', 'rast', 1, 0.2)
 }}}

 3. ST_ApproxMean(rastertable text, rastercolumn text, hasnodata boolean,
 sample_percent double precision) -> double precision

   nband is set to 1

 {{{
 ST_ApproxMean('tmax_2010', 'rast', FALSE, 0.5)

 ST_ApproxMean('precip_2011', 'rast', TRUE, 0.2)
 }}}

 4. ST_ApproxMean(rastertable text, rastercolumn text, sample_percent
 double precision) -> double precision

   nband is set to 1 and hasnodata is set to FALSE

 {{{
 ST_ApproxMean('tmax_2010', 'rast', 0.5)

 ST_ApproxMean('precip_2011', 'rast', 0.2)
 }}}

 5. ST_ApproxMean(rastertable text, rastercolumn text) -> double precision

   nband is set to 1, hasnodata is set to FALSE and sample_percent is set
 to 0.1

 {{{
 ST_ApproxMean('tmax_2010', 'rast')

 ST_ApproxMean('precip_2011', 'rast')
 }}}

 Similar variations will be provided for ST_SummaryStats, ST_StdDev and
 ST_MinMax and corresponding approximation functions.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/931#comment:5>
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