ST_Quantile-AnalyticDB(AnalyticDB)-阿里云帮助中心

Returns the pixel values at specified quantiles for a raster object.

Prerequisites

Before calling ST_Quantile, calculate the quantiles of the raster object using ST_StatsQuantile.

Syntax

setof record ST_Quantile(raster raster_obj,
                   float8[] quantiles default NULL,
                   cstring bands default '',
                   boolean exclude_nodata_value default true,
                   out integer band,
                   out float8 quantile,
                   out float8 value)

Parameters

Parameter	Description
`raster_obj`	The name of the raster object.
`quantiles`	The quantiles to calculate. Valid values: `0.25`, `0.5`, and `0.75`. Specify one or more values as an array.
`bands`	The bands to include in the calculation. Supported formats: `'0-2'` (range) and `'1,2,3'` (list). Band serial numbers start from `0`. Default value: `''` (empty string), which includes all bands.
`exclude_nodata_value`	Specifies whether to include NoData values during calculation. Default value: `true`.
`band`	Output. The band serial number.
`quantile`	Output. The quantile value.
`value`	Output. The pixel value at the quantile.

Examples

Example 1: Query the 0.25 quantile pixel value across all bands

SELECT (ST_Quantile(rast, ARRAY[0.25], '0-2', true)).* FROM rat_quantile WHERE id = 1;

Output:

 band | quantile | value
------+----------+-------
    0 |     0.25 |    11
    1 |     0.25 |    10
    2 |     0.25 |    50
(3 rows)

Example 2: Query all quantile pixel values for band 0

Passing NULL for the quantiles parameter returns pixel values for all three quantiles (0.25, 0.5, and 0.75).

SELECT (ST_Quantile(rast, NULL, '0', true)).* FROM rat_quantile WHERE id = 1;

Output:

 band | quantile | value
------+----------+-------
    0 |     0.25 |    11
    0 |      0.5 |    11
    0 |     0.75 |    65
(3 rows)

Prerequisites

Syntax

Parameters

Examples

See also