[R-sig-Geo] converting shapes to raster

[Michael Sumner]

On Fri, 5 Feb 2016 at 03:50 Antonio Silva <aolinto.lst at gmail.com> wrote:

> Dear list members
>
>
>
> In order to run a niche overlap analysis with nicheOverlap (dismo package)
> I need to convert some shapefiles to raster. I dropped a shapefile as
> example at
> https://www.dropbox.com/s/g6o0vfdx7lr34ma/Species1Shape.rar?dl=0
>
> Marine fish abundance data is aggregated in quadrants of 10 x 10 nautical
> miles. As I have a coast line some quadrants are cut and also I have a
> blank area (land area).
>
> I tried many things like:
>
> shp.frtcost <- readShapePoly("BL10_FRT_COSTEIRA.shp")
>
> plot(shp.frtcost,axes=TRUE,xlim=c(-48,-45),border="grey")
>
> text(coordinates(shp.frtcost),labels=as.character(shp.frtcost at data
> $DENS),cex=0.7)
>
> r <- raster(extent(shp.frtcost),nrows=10,ncols=15)
>
> # or raster(extent(shp.frtcost),nrows=10,ncols=15,vals=shp.frtcost at data
> $DENS)
>
> r <- rasterize(shp.frtcost,r,fun="first")
>
> plot(shp.frtcost,axes=TRUE,xlim=c(-48,-45),border="grey")
>
> plot(r,add=TRUE)
>
>
I can' reproduce the problem? I did this, slightly simpler:

library(raster)

## if you have rgdal available
shp.frtcost <- shapefile("BL10_FRT_COSTEIRA.shp")

## no dropping of projection metadata
r <- raster(shp.frtcost,nrows=10,ncols=15)

r <- rasterize(shp.frtcost,r,fun="first")
plot(shp.frtcost,axes=TRUE,xlim=c(-48,-45),border="grey")
plot(r,add=TRUE)



HTH



>
>
> Shape and raster don't overlay correctly and also I could not pass
> densities values to raster.
>
>
> Limits indicated at extent function do not indicate the limits of my grid.
>
>
>
> Thanks for any help.
>
>
>
> Best regards
>
>
> Antônio Olinto Ávila da Silva
> Instituto de Pesca (Fisheries Institute)
> São Paulo, Brasil
>
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>
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-- 
Dr. Michael Sumner
Software and Database Engineer
Australian Antarctic Division
203 Channel Highway
Kingston Tasmania 7050 Australia

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