The sigma =10 was the example in the book in the link .
after using
?density.ppp
they say that you could use bw.diggle function to find the best bandwidth
although I think the best bandwidth dependes on what you want to see.
plot(density(swedishpines, sigma=bw.diggle(swedishpines)))
check the spatstat book it has good examples for what you want to use.
Juan


On Thu, Jul 4, 2013 at 3:02 PM, Ariel Fuentesdi <ariel.fuentesdi@usach.cl>wrote:

> Thank you,
> Why sigma = 10?, what function can I use for choose the best sigma?. And I
> looked the info about density.ppp and it says it use the Gaussian Kernel.
> But, if we look on wikipedia:
> http://en.wikipedia.org/wiki/Kernel_(statistics) , it says, there are
> more kernel function than the Gaussian Kernel, so my question is how do I
> know wether I have to use for example a Gaussian kernel or a Tricube
> Kernel.
>
> Regards,
> Ariel
>
> 2013/7/4 Juan Tomas Sayago Gomez <juantomas.sayago@gmail.com>
>
>> Hello,
>> you can use the commands in spatstat
>>
>> library(spatstat)
>>
>> summary(swedishpines)
>> plot(density(swedishpines, sigma = 10))
>> then check the help in the spatstat command density.ppp
>>
>> Also check the material in this course
>> http://www.csiro.au/resources/pf16h
>>
>>
>> Juan
>>
>>
>> On Thu, Jul 4, 2013 at 11:32 AM, Ariel Fuentesdi <
>> ariel.fuentesdi@usach.cl> wrote:
>>
>>> Hello,
>>>
>>> I have raingauges as points and I want to make an heatmap with those
>>> points. So, I understand I need to do a kernel density estimation, but,
>>> there are different kernel functions. Thus, my questions is: how do I
>>> know
>>> which kernel function I need to apply to my data? Do I need to run a
>>> previous test first?
>>>
>>> I believe I can select the function using grass, but how can I do it with
>>> R? Do I have to use the KernSmooth package? How Can I map that ?
>>>
>>> Regards,
>>> Ariel
>>>
>>>         [[alternative HTML version deleted]]
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo@r-project.org
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>
>>
>>
>> --
>> Juan Tomás Sayago Gómez
>> Graduate Research Assistant
>> West Virginia University - RRI
>> 886 Chestnut Ridge Road, Room 520
>> P.O. Box 6825
>> Morgantown, WV 26506-6825
>>
>
>


-- 
Juan Tomás Sayago Gómez
Graduate Research Assistant
West Virginia University - RRI
886 Chestnut Ridge Road, Room 520
P.O. Box 6825
Morgantown, WV 26506-6825

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