Interesting. Works for me "out of the box".

> sessionInfo()
R version 2.11.0 (2010-04-22)
i386-pc-mingw32

locale:
[1] LC_COLLATE=Slovenian_Slovenia.1250  LC_CTYPE=Slovenian_Slovenia.1250
[3] LC_MONETARY=Slovenian_Slovenia.1250 LC_NUMERIC=C
[5] LC_TIME=Slovenian_Slovenia.1250

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] raster_1.0.4 sp_0.9-62

loaded via a namespace (and not attached):
[1] grid_2.11.0    lattice_0.18-5


Cheers,
Roman


On Tue, Jun 22, 2010 at 10:37 AM, Michael Sumner <mdsumner@gmail.com> wrote:

> Sorry, but it still doesn't work for me. I'm surprised you could get
> passed the first line, since "projs" is not an argument to raster -
> it's not necessary for your example to have that set though, so I
> ignore it.
>
> I had to install igraph package as well, but still this fails at the
> gridDistance line. Can you let us know your OS, R and package versions
> for raster, sp, and igraph?  Use sessionInfo()  please.
>
> library(raster)
> library(sp)
> library(igraph)
>
> rst <- raster(nrow = 200, ncol = 200, xmn = -100, xmx = 100, ymn =
> -100, ymx = 100)
> sample.matrix <- t(matrix(c(50,-50, 50,50, -50,50, -50,-50), 2, 4))
> sample.matrix <- rbind(sample.matrix, sample.matrix[1,])
> sq.polygon <- SpatialPolygons(list(Polygons(list(Polygon(sample.matrix)),
> ID = "effect_dist")))
> rst[] <- runif(ncell(rst))
> xy <- matrix(c(0,0), 1, 2)
>
> rst.poly <- polygonsToRaster(sq.polygon, rst)
> rst.lines <- linesToRaster(sq.polygon, rst)
>
> rst.lines[rst.lines > 0] <- 0
>
> rst.point <- pointsToRaster(rst, xy)
>
> rst.cover <- cover(rst.point, rst.lines)
>
> ## fails at this line
> rst.grid <- gridDistance(rst.cover)
> rst.grid[!is.na(rst.lines)] <- NA
> plot(rst.grid)
>
> sessionInfo()
>
> R version 2.11.1 (2010-05-31)
> x86_64-pc-mingw32
>
> locale:
> [1] LC_COLLATE=English_Australia.1252  LC_CTYPE=English_Australia.1252
>   LC_MONETARY=English_Australia.1252
> [4] LC_NUMERIC=C                       LC_TIME=English_Australia.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] igraph_0.5.3 raster_1.1.7 sp_0.9-64
>
> loaded via a namespace (and not attached):
> [1] grid_2.11.1    lattice_0.18-8 tools_2.11.1
>
>
> On Tue, Jun 22, 2010 at 6:28 PM, Roman Luštrik <roman.lustrik@gmail.com>
> wrote:
> > Thank you Michael for taking interest in my problem. Here is the code
> that
> > should work. The only difference is that here, for a polygon, I use a
> square
> > instead of a circle (no biggie). I suspect gridDistance may have
> something
> > to do with the "hexagon".
> >
> > library(raster)
> > library(sp)
> > rst <- raster(nrow = 200, ncol = 200, xmn = -100, xmx = 100, ymn = -100,
> ymx
> > = 100, projs = "+proj=NA")
> > sample.matrix <- t(matrix(c(50,-50, 50,50, -50,50, -50,-50), 2, 4))
> > sample.matrix <- rbind(sample.matrix, sample.matrix[1,])
> > sq.polygon <- SpatialPolygons(list(Polygons(list(Polygon(sample.matrix)),
> ID
> > = "effect_dist")))
> > rst[] <- runif(ncell(rst))
> > xy <- matrix(c(0,0), 1, 2)
> >
> > rst.poly <- polygonsToRaster(sq.polygon, rst)
> > rst.lines <- linesToRaster(sq.polygon, rst)
> >
> > rst.lines[rst.lines > 0] <- 0
> > rst.point <- pointsToRaster(rst, xy)
> >
> > rst.cover <- cover(rst.point, rst.lines)
> > rst.grid <- gridDistance(rst.cover)
> > rst.grid[!is.na(rst.lines)] <- NA
> > plot(rst.grid)
> >
> >
> > Cheers,
> > Roman
> >
> >
> >
> >
> > On Tue, Jun 22, 2010 at 9:55 AM, Michael Sumner <mdsumner@gmail.com>
> wrote:
> >
> >> Could you please provide a reproducible example with useable code?
> >>
> >> Cheers, Mike.
> >>
> >> On Tue, Jun 22, 2010 at 5:36 PM, Roman Luštrik <roman.lustrik@gmail.com
> >
> >> wrote:
> >> > Can someone explain to me why values of distances from a point are not
> in
> >> a
> >> > uniform, circle-like fashion, but rather form a hexagon shape (see
> >> > image<http://imagepaste.nullnetwork.net/viewimage.php?id=1075>)?
> >> > Here is the code I'm using to produce this plot (kudos to
> >> > Robert<
> >>
> http://r-sig-geo.2731867.n2.nabble.com/assigning-raster-cell-values-based-on-predefined-criteria-td4929775.html#a4929775
> >> >).
> >> > Raster projection is "+projs = NA".
> >> >
> >> > rst.poly <- polygonsToRaster(circle.polygon, rst) #circle.polygon is
> the
> >> > polygon I'm overlaying, rst is the raster
> >> > rst.lines <- linesToRaster(circle.polygon, rst)
> >> > rst.lines[rst.lines > 0] <- 0
> >> > rst.point <- pointsToRaster(rst, xy[[i]][j,]) #xy is the point from
> where
> >> > the distances are calculated
> >> > rst.cover <- cover(rst.point, rst.lines)
> >> > rst.grid <- gridDistance(rst.cover)
> >> > rst.grid[!is.na(rst.lines)] <- NA
> >> > plot(rst.grid)
> >> >
> >> >
> >> > Cheers,
> >> > Roman
> >> >
> >> >
> >> > --
> >> > In God we trust, all others bring data.
> >> >
> >> >        [[alternative HTML version deleted]]
> >> >
> >> > _______________________________________________
> >> > R-sig-Geo mailing list
> >> > R-sig-Geo@stat.math.ethz.ch
> >> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >> >
> >>
> >
> >
> >
> > --
> > In God we trust, all others bring data.
> >
> >
> >
> > --
> > In God we trust, all others bring data.
> >
> >        [[alternative HTML version deleted]]
> >
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo@stat.math.ethz.ch
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
> >
>



-- 
In God we trust, all others bring data.

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