[R-sig-Geo] Multiplying a raster object

Tadaishi Yatabe-Rodriguez tyatabe at ucdavis.edu
Thu Feb 25 18:32:33 CET 2016

Thanks Loic,

That helps a lot, actually. I used the wrong factor for transforming.
Still adding the values of my raster don't add up to the points of the
original ppp object. So I suppose there are better approaches than
multiplying the raster by factor. If someone else wants to chip in on this
it'll be great.

Thanks again,


On Wed, Feb 24, 2016 at 4:56 AM, Loïc Dutrieux <loic.dutrieux at wur.nl> wrote:

> On 02/23/2016 09:22 PM, Tadaishi Yatabe-Rodriguez wrote:
>> Hi community,
>> I have a raster object of a kernel density, where the linear unit is
>> meter,
>> and when I plot it it gives me very small density values (units per sq
>> meter, I suppose). I figure that if I multiply it, say by a 1000, it will
>> give density values in units per sq km.
> I don't know much about kernel densities, but if you want to convert
> units/m^2 to units/km^2 you'd have to multiply by 1 000 000 instead of
> 1000. Hope that helps explaining the incoherence in your results.
> It looks good on the legend, but I
>> wonder: is this a correct thing to do? I wonder this because when I add
>> the
>> values of the raster it does not add up to the number of points in my
>> original ppp object from which I created the density.
>> Thanks,
>> Tada
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*Tadaishi Yatabe*
Center for Animal Disease Modeling and Surveillance (CADMS)
Department of Medicine and Epidemiology
School of Veterinary Medicine
University of California Davis


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