FROM (SELECT ST_BandMetaData(rast,generate_series(1,2)) As bmd
FROM dummy_rast WHERE rid = 10) AS foo;
--result --
- pixeltype | exclude_nodata_valuevalue | nodatavalue | isoutdb | path
+ pixeltype | hasnodata | nodatavalue | isoutdb | path
-----------+----------------+-------------+---------+------
1BB | f | 0 | f |
4BUI | f | 0 | f |
<sect1 id="RasterBand_Stats">
<title>Raster Band Statistics and Analytics</title>
+
+ <refentry id="RT_ST_Quantile">
+ <refnamediv>
+ <refname>ST_Quantile</refname>
+ <refpurpose>Compute quantiles in the context of the sample or population. Thus, a value could be examined to be at the raster's 25%, 50%, 75% percentile.</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>SETOF quantile <function>ST_Quantile</function></funcdef>
+ <paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
+ <paramdef choice='opt'><type>integer </type> <parameter>nband=1</parameter></paramdef>
+ <paramdef choice='opt'><type>boolean </type> <parameter>exclude_nodata_value=true</parameter></paramdef>
+ <paramdef choice='opt'><type>double precision[] </type> <parameter>quantiles=NULL</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>double precision <function>ST_Quantile</function></funcdef>
+ <paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
+ <paramdef><type>double precision </type> <parameter>quantile</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>double precision <function>ST_Quantile</function></funcdef>
+ <paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
+ <paramdef><type>boolean </type> <parameter>exclude_nodata_value</parameter></paramdef>
+ <paramdef choice='opt'><type>double precision </type> <parameter>quantile=NULL</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>double precision <function>ST_Quantile</function></funcdef>
+ <paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
+ <paramdef><type>integer </type> <parameter>nband</parameter></paramdef>
+ <paramdef><type>double precision </type> <parameter>quantile</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>double precision <function>ST_Quantile</function></funcdef>
+ <paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
+ <paramdef><type>integer </type> <parameter>nband</parameter></paramdef>
+ <paramdef><type>double precision </type> <parameter>quantile</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsection>
+ <title>Description</title>
+
+ <para>Compute quantiles in the context of the sample or population. Thus, a value could be examined to be at the raster's 25%, 50%, 75% percentile.</para>
+ <note><para>If <varname>exclude_nodata_value</varname> is set to true, will also count pixels with no data. Set <varname>exclude_nodata_value</varname> to false to get only pixels with data</para></note>
+ <para>Availability: 2.0.0 </para>
+ </refsection>
+
+ <refsection>
+ <title>Examples</title>
+
+ <programlisting>
+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
+</programlisting>
+<programlisting>
+--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
+</programlisting>
+ </refsection>
+
+ <refsection>
+ <title>See Also</title>
+ <para><xref linkend="RT_ST_Count" />, <xref linkend="RT_ST_SetBandNoDataValue" /></para>
+ </refsection>
+ </refentry>
<refentry id="RT_ST_Count">
<refnamediv>
<refname>ST_Count</refname>
<para>Returns the number of pixels in a given band of a raster or raster coverage. If no band is specified <varname>nband</varname> defaults to 1. </para>
<note><para>If <varname>exclude_nodata_value</varname> is set to true, will also count pixels with no data. Set <varname>exclude_nodata_value</varname> to false to get only pixels with data</para></note>
<para>Availability: 2.0.0 </para>
- <warning><para>This currently does the opposite of what I just said. Will be fixed to agree with the documentation or the documentation will be fixed to agree with the behavior.</para></warning>
</refsection>
<refsection>
:
</programlisting>
+<programlisting>
+--real live example. Count all the pixels in an aerial raster tile band 2 intersecting a geometry
+-- and return only the pixel band values that have a count > 500
+SELECT (pvc).value, SUM((pvc).count) As total
+FROM (SELECT ST_ValueCount(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)
+ )
+ ) As foo
+ GROUP BY (pvc).value
+ HAVING SUM((pvc).count) > 500
+ ORDER BY (pvc).value;
+
+ value | total
+-------+-----
+ 51 | 502
+ 54 | 521
+</programlisting>
</refsection>
<refsection>
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