[postgis-users] ST_Quantile

Fri Jan 27 13:07:12 PST 2012

Joan,

I've committed a fix for that problem in r8949.

-bborie

On 01/27/2012 11:52 AM, Bborie Park wrote:
> The way you called ST_Quantile is perfectly acceptable as there are
> variants of ST_Quantile that support that form.
>
> I'm fixing the problem now and should have it committed later today.
>
> -bborie
>
> On 01/27/2012 11:42 AM, Joan wrote:
>> The 0.75 is the quantile.
>>
>> I will report the bugs. Thanks for the help/info.
>>
>> Joan
>>
>> On 27 January 2012 20:31, Stephen
>> Woodbridge<woodbri at swoodbridge.com>wrote:
>>
>>> Joan,
>>>
>>> Looking at the function the Bborie posted:
>>>
>>>
>>> st_quantile(rastertable text, rastercolumn text, nband int DEFAULT
>>> 1, exclude_nodata_value boolean DEFAULT TRUE, quantiles double
>>> precision[] DEFAULT NULL)
>>>
>>> The 3rd parameter is the band number. What is the 0.75 supposed to
>>> represent? My guess is that is getting truncated to 0 and it is
>>> trying to
>>> process band=0 which might not be valid.
>>>
>>> But it should not crash, so please write two bugs against this:
>>> 1. for the missing doc
>>> 2. for the crash if you enter 0.75
>>>
>>> Thanks,
>>> -Steve
>>>
>>>
>>> On 1/27/2012 2:19 PM, Joan wrote:
>>>
>>>> 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
>>>> <mailto:woodbri at swoodbridge.**com<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>
>>>> <mailto: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>
>>>> <mailto:bkpark at ucdavis.edu<mailto:bkpark at ucdavis.edu>>
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-- 
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark at ucdavis.edu