[postgis-users] ST_Quantile

[Joan]

Hi Steve,

I have gotten the same problem (db server stopped running).

Joan

On 27 January 2012 20:05, Stephen Woodbridge <woodbri at swoodbridge.com>wrote:

> Joan,
>
> I've never used these function, but try doing:
>
> select st_quantile('kbd_ext', 'rast', 0.75);
>
> Since you probably do not want this called once for every row in the table.
>
> -Steve
>
>
> On 1/27/2012 2:03 PM, Joan wrote:
>
>> Hi Bborie,
>>
>> This is my query and it crashes the db server.
>> select st_quantile('kbd_ext', 'rast', 0.75) from kbd_ext limit 10;
>>
>> Joan
>>
>> On 27 January 2012 19:14, Bborie Park <bkpark at ucdavis.edu
>> <mailto:bkpark at ucdavis.edu>> wrote:
>>
>>    Hey Joan,
>>
>>    Assuming your whole coverage is in a table, you should use the
>>    table/column version of ST_Quantile (which by the looks of it is
>>    undocumented for some reason).
>>
>>    The function definition of ST_Quantile(rastertable, rastercolumn) is...
>>
>>    st_quantile(rastertable text, rastercolumn text, nband int DEFAULT
>>    1, exclude_nodata_value boolean DEFAULT TRUE, quantiles double
>>    precision[] DEFAULT NULL)
>>
>>    At the moment an aggregate version of ST_Quantile (and the other
>>    basic stats functions) does not exist.  It is expected that one will
>>    be written for PostGIS 2.1 assuming dev-time is available.
>>
>>    -bborie
>>
>>
>>    On 01/27/2012 09:06 AM, Joan wrote:
>>
>>        Hi,
>>
>>        I would like to find the quantile values of a whole raster
>>        coverage, but
>>        ST_Quantile returns quantile values of each tile. Which would be
>>        the best
>>        method to approximate the quantile value of the whole coverage?
>>
>>        Regards,
>>
>>        Joan
>>
>>
>>
>>
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>>
>>    --
>>    Bborie Park
>>    Programmer
>>    Center for Vectorborne Diseases
>>    UC Davis
>>    530-752-8380
>>    bkpark at ucdavis.edu <mailto:bkpark at ucdavis.edu>
>>
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