[R-sig-Geo] PCA (Factor Analysis) with R spatial

[Stéphane Dray]

you can have a look to 
http://pbil.univ-lyon1.fr/members/dray/articles/SD807.php which presents 
a spatially-constrained version of multivariate analysis. It is 
implemented in the multispati function of the ade4 package.

Cheers.

Raphael Saldanha wrote:
> Hi Brian,
>
> A few time ago, I had recommended these references to a new "spatial" R
> user:
>
> You need first take a good look at the spdep package documentation
> (here <http://cran.r-project.org/web/packages/spdep/index.html>
> and here <http://cran.r-project.org/web/packages/spdep/spdep.pdf>),  and
> some good tutorials maded by the CISS <http://www.csiss.org/>, like
> this one<http://geodacenter.asu.edu/system/files/rex1.pdf>. Also,
> I recommed the Roger Bivand's book Applied Spatial
> Analysis<http://www.springer.com/public+health/epidemiology/book/978-0-387-78170-9>
> .
>
> A while ago, I had done some spatial analysis with PCA help. First, I had
> managed the spatial lag of the variables, and then, with detrended
> variables, started the PCA analysis. Please, let me known more about your
> research.
>
> 2010/4/6 brian cooper <brianadr at optusnet.com.au>
>
>   
>> Dear List,
>>
>>
>>
>> I am just learning R and associated spatial analysis.
>>
>>
>>
>> I am attempting to compare the impact of location has on a PCA. To do this
>> I
>> will be using the same data set to conduct a PCA using SPSS. Then using the
>> same data set attached to LAT/LONG coordinates (Polygon Centroid)   and
>> polygons, I will attempt to conduct a PCA using geo statistics.
>>
>>
>>
>> The question I am asking is there any difference between aspatial and
>> spatial analysis approaches on the same data. The particular approach is
>> factor analysis.
>>
>>
>>
>> The file I am using has approximately 640 cases and 23 variables one of
>> which is the geographical tag (in this case postcode), SPSS format. I have
>> a
>> polygon file for the postcodes, which is currently in MapInfo format.
>>
>>
>>
>> In my preliminary analysis, I established using vertical mapper (a MapInfo
>> add-on) there was a difference in results.
>>
>>
>>
>> Now in R spatial, I want to replicate the results. Is it possible to
>> include
>> the polygon as a variable in the calculation as opposed to the centroid of
>> the polygon?
>>
>> 1.  How does one store the results especially the factor scores associated
>> with each row as new columns.
>>
>> 2.  Is it better to have the variables attached to the polygon, or merge
>> files.
>>
>> 3.  Which is the most effective modules to use.
>>
>>
>>
>> Brian Cooper
>>
>>
>>        [[alternative HTML version deleted]]
>>
>> _______________________________________________
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>> R-sig-Geo at stat.math.ethz.ch
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>>
>>     
>
>
>
>   

-- 
Stéphane DRAY (dray at biomserv.univ-lyon1.fr )
Laboratoire BBE-CNRS-UMR-5558, Univ. C. Bernard - Lyon I
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Tel: 33 4 72 43 27 57       Fax: 33 4 72 43 13 88
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