Thank you Jacob for pointing out the obvious I missed. Looks like distance()
will do what I want.

r <- raster(ncol=36,nrow=36, projs = "+proj=NA")
r[] <- NA
r[500] <- 1
dist <- distance(r)
plot(dist)

Michael, compare this output to (notice +proj=NA - see Roberts
comments here<http://r-sig-geo.2731867.n2.nabble.com/assigning-raster-cell-values-based-on-predefined-criteria-tp4929775p4945952.html>
):

r <- raster(ncol=36,nrow=36)
r[] <- NA
r[500] <- 1
dist <- distance(r)
plot(dist)


Cheers,
Roman



On Tue, Jun 22, 2010 at 11:45 AM, Jacob van Etten
<jacobvanetten@yahoo.com>wrote:

> Hi Roman,
>
> Nice picture.
>
> The help file says:
>
> "Distances are calculated by summing local distances between cells, which
> are connected with their neighbours in 8 directions."
>
> Hence, you get a hexagonal shape if the grid doesn´t have any "islands" the
> shortest routes have to avoid.
>
> Perhaps distance() is what you really want?
>
> Otherwise, costDistance() in gdistance may do what you want.
>
> Best,
>
> Jacob.
>
> --- On *Tue, 6/22/10, Roman Luštrik <roman.lustrik@gmail.com>* wrote:
>
>
> From: Roman Luštrik <roman.lustrik@gmail.com>
> Subject: [R-sig-Geo] distances values from a point exhibit a hexagon-like
> distribution
> To: "r-sig-geo" <r-sig-geo@stat.math.ethz.ch>
> Date: Tuesday, June 22, 2010, 9:36 AM
>
> 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.
>
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>
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>
>
>


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

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