ST_Quantile

ST_Quantile
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Name

ST_Quantile — 在样本或总体的上下文中计算栅格或栅格表覆盖率的分位数。因此，可以将值检查为位于栅格的25%、50%、75%的百分位数。

Synopsis

SETOF record ST_Quantile ( raster rast , integer nband=1 , boolean exclude_nodata_value=true , double precision[] quantiles=NULL ) ;

SETOF record ST_Quantile ( raster rast , double precision[] quantiles ) ;

SETOF record ST_Quantile ( raster rast , integer nband , double precision[] quantiles ) ;

double precision ST_Quantile ( raster rast , double precision quantile ) ;

double precision ST_Quantile ( raster rast , boolean exclude_nodata_value , double precision quantile=NULL ) ;

double precision ST_Quantile ( raster rast , integer nband , double precision quantile ) ;

double precision ST_Quantile ( raster rast , integer nband , boolean exclude_nodata_value , double precision quantile ) ;

double precision ST_Quantile ( raster rast , integer nband , double precision quantile ) ;

描述

在样本或总体的上下文中计算栅格或栅格表覆盖率的分位数。因此，可以将值检查为位于栅格的25%、50%、75%的百分位数。


	如果 `exclude_nodata_value` 设置为False，则还将计算没有数据的像素。

已更改：3.1.0删除ST_Quantile(TABLE_NAME，COLUMN_NAME)变量。

可用性：2.0.0

示例

UPDATE dummy_rast SET rast = ST_SetBandNoDataValue(rast,249) WHERE rid=2;
--Example will consider only pixels of band 1 that are not 249 and in named quantiles --

SELECT (pvq).*
FROM (SELECT ST_Quantile(rast, ARRAY[0.25,0.75]) As pvq
    FROM dummy_rast WHERE rid=2) As foo
    ORDER BY (pvq).quantile;

 quantile | value
----------+-------
     0.25 |   253
     0.75 |   254

SELECT ST_Quantile(rast, 0.75) As value
    FROM dummy_rast WHERE rid=2;

value
------
  254

--real live example.  Quantile of all pixels in band 2 intersecting a geometry
SELECT rid, (ST_Quantile(rast,2)).* As pvc
    FROM o_4_boston
        WHERE ST_Intersects(rast,
            ST_GeomFromText('POLYGON((224486 892151,224486 892200,224706 892200,224706 892151,224486 892151))',26986)
            )
ORDER BY value, quantile,rid
;


 rid | quantile | value
-----+----------+-------
   1 |        0 |     0
   2 |        0 |     0
  14 |        0 |     1
  15 |        0 |     2
  14 |     0.25 |    37
   1 |     0.25 |    42
  15 |     0.25 |    47
   2 |     0.25 |    50
  14 |      0.5 |    56
   1 |      0.5 |    64
  15 |      0.5 |    66
   2 |      0.5 |    77
  14 |     0.75 |    81
  15 |     0.75 |    87
   1 |     0.75 |    94
   2 |     0.75 |   106
  14 |        1 |   199
   1 |        1 |   244
   2 |        1 |   255
  15 |        1 |   255

另请参阅

ST_Count , ST_SummaryStats , ST_SummaryStatsAgg , ST_SetBandNoDataValue