ST_Histogram — Returns a set of record summarizing a raster or raster coverage data distribution separate bin ranges. Number of bins are autocomputed if not specified.
SETOF record ST_Histogram(
raster rast, integer nband=1, boolean exclude_nodata_value=true, integer bins=autocomputed, double precision[] width=NULL, boolean right=false)
;
SETOF record ST_Histogram(
raster rast, integer nband, integer bins, double precision[] width=NULL, boolean right=false)
;
SETOF record ST_Histogram(
raster rast, integer nband, boolean exclude_nodata_value, integer bins, boolean right)
;
SETOF record ST_Histogram(
raster rast, integer nband, integer bins, boolean right)
;
Returns set of records consisting of min, max, count, percent for a given raster band for each bin. If no band is specified nband
defaults to 1.
By default only considers pixel values not equal to the |
width
width: an array indicating the width of each category/bin. If the number of bins is greater than the number of widths, the widths are repeated.
Example: 9 bins, widths are [a, b, c] will have the output be [a, b, c, a, b, c, a, b, c]
bins
Number of breakouts -- this is the number of records you'll get back from the function if specified. If not specified then the number of breakouts is autocomputed.
right
compute the histogram from the right rather than from the left (default). This changes the criteria for evaluating a value x from [a, b) to (a, b]
Changed: 3.1.0 Removed ST_Histogram(table_name, column_name) variant.
Availability: 2.0.0
SELECT band, (stats).* FROM (SELECT rid, band, ST_Histogram(rast, band) As stats FROM dummy_rast CROSS JOIN generate_series(1,3) As band WHERE rid=2) As foo; band | min | max | count | percent ------+-------+-------+-------+--------- 1 | 249 | 250 | 2 | 0.08 1 | 250 | 251 | 2 | 0.08 1 | 251 | 252 | 1 | 0.04 1 | 252 | 253 | 2 | 0.08 1 | 253 | 254 | 18 | 0.72 2 | 78 | 113.2 | 11 | 0.44 2 | 113.2 | 148.4 | 4 | 0.16 2 | 148.4 | 183.6 | 4 | 0.16 2 | 183.6 | 218.8 | 1 | 0.04 2 | 218.8 | 254 | 5 | 0.2 3 | 62 | 100.4 | 11 | 0.44 3 | 100.4 | 138.8 | 5 | 0.2 3 | 138.8 | 177.2 | 4 | 0.16 3 | 177.2 | 215.6 | 1 | 0.04 3 | 215.6 | 254 | 4 | 0.16
SELECT (stats).* FROM (SELECT rid, ST_Histogram(rast, 2,6) As stats FROM dummy_rast WHERE rid=2) As foo; min | max | count | percent ------------+------------+-------+--------- 78 | 107.333333 | 9 | 0.36 107.333333 | 136.666667 | 6 | 0.24 136.666667 | 166 | 0 | 0 166 | 195.333333 | 4 | 0.16 195.333333 | 224.666667 | 1 | 0.04 224.666667 | 254 | 5 | 0.2 (6 rows) -- Same as previous but we explicitly control the pixel value range of each bin. SELECT (stats).* FROM (SELECT rid, ST_Histogram(rast, 2,6,ARRAY[0.5,1,4,100,5]) As stats FROM dummy_rast WHERE rid=2) As foo; min | max | count | percent -------+-------+-------+---------- 78 | 78.5 | 1 | 0.08 78.5 | 79.5 | 1 | 0.04 79.5 | 83.5 | 0 | 0 83.5 | 183.5 | 17 | 0.0068 183.5 | 188.5 | 0 | 0 188.5 | 254 | 6 | 0.003664 (6 rows)