[R-sig-Geo] R function checking/transforming CRS layer R function

[Tristan Bourgeois]

Hi Erin !

Yes,   I tried to apply my function to "UH"  which is a shapefile.




2017-01-27 11:28 GMT+01:00 Hodgess, Erin <HodgessE at uhd.edu>:

> Hi Tristan!
>
> I'm looking at your code right now.  What is your input, please; the UH?
>
> Thanks,
> Erin
>
>
> Erin M. Hodgess
> Associate Professor
> Department of Mathematics and Statistics
> University of Houston - Downtown
> mailto: hodgesse at uhd.edu
>
> ________________________________________
> From: R-sig-Geo <r-sig-geo-bounces at r-project.org> on behalf of Tristan
> Bourgeois <tristan.bourgeois at gmail.com>
> Sent: Friday, January 27, 2017 3:41 AM
> To: r-sig-geo at r-project.org
> Subject: [R-sig-Geo] R function checking/transforming CRS layer R function
>
> Dear all,
>
> I'm trying to build up an r function able to check if the projection system
> of a layer is in Lambert93 (WSG code : 2154) .
> If the condition is false I want to transform the CRS into Lambert 93.
>
> This is what I wrote :
>
> > CRSfunction<-function(couche)
> + {
> +   prj_couche<-CRS(couche)
> +   prj<-CRS("+proj=lcc +lat_1=49 +lat_2=44 +lat_0=46.5 +lon_0=3
> +x_0=700000 +y_0=6600000 +ellps=GRS80 +units=m +no_defs")
> +   if (prj_couche!=prj)
> +     {CRS(couche)="+proj=lcc +lat_1=49 +lat_2=44 +lat_0=46.5 +lon_0=3
> +x_0=700000 +y_0=6600000 +ellps=GRS80 +units=m +no_defs" }
> + }
> > CRSfunction(UH)
> Error in CRS(couche) : no method for coercing this S4 class to a vector
> In addition: Warning message:
> In is.na(projargs) : is.na() applied to non-(list or vector) of type 'S4'
> Called from: CRS(couche)
> Browse[1]> Q
>
>
> Does anybody can help to deal with the mistake I 've made ??
>
> Plus, I'm not sure the function will work with both raster and shapefiles.
>
> Cheers.
>
>
> Tristan Bourgeois.
> R New User
>
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>
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-- 
Tristan Bourgeois

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