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List: postgis-users
Subject: Re: [postgis-users] stddev from average cell value of a raster
From: Bborie Park <dustymugs () gmail ! com>
Date: 2014-01-31 14:56:18
Message-ID: CAKVfRvHZ4piHd6WhxmQHjCtoxZ1YeVNXt2BYv3fHK8Y9WHJpKw () mail ! gmail ! com
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Your usage of ST_SummaryStats() won't work. ST_SummaryStats provides the
average and the standard deviation of the input raster...
SELECT (ST_SummaryStats(rast)).mean, (ST_SummaryStats(rast)).stddev FROM
mytable
-bborie
On Fri, Jan 31, 2014 at 5:59 AM, <g.singh@utwente.nl> wrote:
> Dear All,
>
>
>
> I have a raster in which the pixel values ranges from 0 - 1. I want to
> find the standard deviation of from the average cell value of the raster
> for which I use a query as under. The query can be executed but do not see
> any values in data output window. I initially thought that it could be
> smaller cell values, and to compensate that I use a factor of 10^10 but
> still the problem remains. Can someone please suggest where I am going
> wrong.
>
>
>
> with
>
> cellscores as (
>
> select rid, gaztext_id, dist_meter, direction,sigma_dist,
> sigma_dir,sdis,sdir, (10^10) * cellvalue as cellvalue, maxprob, rastersize
>
> from cellscores_new_final_raster_parm_disdir_spatialhint where
> gaztext_id=2502 and count=1 and rid=651
>
> )
>
> ,avg_value as (
>
> select c.rid, c.gaztext_id, c.dist_meter, c.direction,c.sigma_dist,
> c.sigma_dir,c.sdis,c.sdir, c.cellvalue, c.maxprob, c.rastersize, n.rast,
>
> (10^10)*(sum(st_summarystats(n.rast))/c.rastersize) as average_cellvalue
>
> from cellscores c JOIN new_final_raster_parm_disdir_spatialhint n ON
> n.rid=c.rid
>
> order by c.gaztext_id
>
> )
>
> select stddev(sum(st_summarystats(rast))/rastersize)
>
> from avg_value
>
>
>
>
>
> Tanks and Regards,
>
> Gaurav
>
> _______________________________________________
> postgis-users mailing list
> postgis-users@lists.osgeo.org
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>
[Attachment #5 (text/html)]
<div dir="ltr">Your usage of ST_SummaryStats() won't work. ST_SummaryStats \
provides the average and the standard deviation of the input \
raster...<div><br></div><div>SELECT (ST_SummaryStats(rast)).mean, \
(ST_SummaryStats(rast)).stddev FROM mytable</div>
<div><br></div><div>-bborie</div></div><div class="gmail_extra"><br><br><div \
class="gmail_quote">On Fri, Jan 31, 2014 at 5:59 AM, <span dir="ltr"><<a \
href="mailto:g.singh@utwente.nl" target="_blank">g.singh@utwente.nl</a>></span> \
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex">
<div lang="EN-US" link="blue" vlink="purple">
<div>
<p class="MsoNormal">Dear All,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I have a raster in which the pixel values ranges from 0 – \
1. I want to find the standard deviation of from the average cell value of the raster \
for which I use a query as under. The query can be executed but do not see any values \
in data output window. I initially thought that it could be smaller cell \
values, and to compensate that I use a factor of 10^10 but still the problem remains. \
Can someone please suggest where I am going wrong.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">with <u></u><u></u></p>
<p class="MsoNormal">cellscores as (<u></u><u></u></p>
<p class="MsoNormal">select rid, gaztext_id, dist_meter, direction,sigma_dist, \
sigma_dir,sdis,sdir, (10^10) * cellvalue as cellvalue, maxprob, \
rastersize<u></u><u></u></p> <p class="MsoNormal">from \
cellscores_new_final_raster_parm_disdir_spatialhint where gaztext_id=2502 and count=1 \
and rid=651<u></u><u></u></p> <p class="MsoNormal">)<u></u><u></u></p>
<p class="MsoNormal">,avg_value as (<u></u><u></u></p>
<p class="MsoNormal">select c.rid, c.gaztext_id, c.dist_meter, \
c.direction,c.sigma_dist, c.sigma_dir,c.sdis,c.sdir, c.cellvalue, c.maxprob, \
c.rastersize, n.rast,<u></u><u></u></p> <p \
class="MsoNormal">(10^10)*(sum(st_summarystats(n.rast))/c.rastersize) as \
average_cellvalue<u></u><u></u></p> <p class="MsoNormal">from cellscores c JOIN \
new_final_raster_parm_disdir_spatialhint n ON n.rid=c.rid <u></u><u></u></p>
<p class="MsoNormal">order by c.gaztext_id<u></u><u></u></p>
<p class="MsoNormal">)<u></u><u></u></p>
<p class="MsoNormal">select \
stddev(sum(st_summarystats(rast))/rastersize)<u></u><u></u></p> <p \
class="MsoNormal">from avg_value<u></u><u></u></p> <p \
class="MsoNormal"><u></u> <u></u></p> <p \
class="MsoNormal"><u></u> <u></u></p> <p class="MsoNormal">Tanks and \
Regards,<u></u><u></u></p> <p class="MsoNormal">Gaurav<u></u><u></u></p>
</div>
</div>
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