[R] about"Riply's K function"and "envelope"

[Sundar Dorai-Raj]

So as not to offend the authors of spatial and splancs, please describe 
what "not good" means in this context? What is it about 
spatstat::envelope that cannot be achieved by spatial::Kenvl? Besides, 
the author of the K-function (Ripley himself) wrote the latter package. 
Here's an example:

library(spatial)
set.seed(24)
X <- list(x = runif(100), y = runif(100),
           area = c(xl = 0, xu = 1, yl = 0, xu = 1))
ppregion(X)
plot(Kfn(X, 0.5), type = "b", xlab = "distance", ylab = "L(t)")
set.seed(42)
lims <- Kenvl(0.5, 100, Psim(69))
lines(lims$x, lims$l, lty = 2, col = "darkred")
lines(lims$x, lims$u, lty = 2, col = "darkred")

library(spatstat)
Y <- ppp(X$x, X$y, X$area[1:2], X$area[3:4])
set.seed(42)
Yenv <- envelope(Y, nsim = 100)

Of course, these will look different because Kenvl and Kfn actually 
compute the L-function (which is a better visual tool), but otherwise 
they should be very similar.

(I must admit I haven't read all the documentation for spatstat so I may 
be off base as to what ?envelope is actually doing.)

--sundar


zhang jian wrote:
> I have tried the package"spatial" and "splance".But it is not good.
> I think there are some questions when I run the programs.
> I attach a part of data. can you help me try to do it? And attach a simple
> program to me.
> my plot is square, 500m*500m.
> 
>>PIKO[1:10,]
> 
>      code species  dbh     x     y   tag status branch
> 92  10142    PIKO 38.9  6.05 12.81 10165  alive      0
> 109 10213    PIKO 41.0  6.71 26.21 10202  alive      0
> 135 10222    PIKO 48.3 18.98 21.28 10214  alive      0
> 146 10223    PIKO 47.0 19.45 22.83 10224  alive      0
> 147 10223    PIKO 20.0 19.74 28.65 10225  alive      0
> 151 10223    PIKO 23.3 17.03 28.88 10229  alive      0
> 152 10223    PIKO 33.5 16.94 27.25 10230  alive      0
> 176 10232    PIKO 43.5 19.20 30.88 10248  alive      0
> 181 10233    PIKO 39.0 18.10 35.60 10252  alive      0
> 212 10243    PIKO 71.2  6.94 37.27 10281  alive      0
> 
> "x,y" are coordinations. I want to use them to do Ripley's K analysis.
> thank you very much!
> Help me!
>                                           jian zhang
> 
> On 2/27/06, Sundar Dorai-Raj <sundar.dorai-raj at pdf.com> wrote:
> 
>>
>>
>>zhang jian wrote:
>>
>>>hi!
>>>I did Riply's K function and envelope in the package "SPATSTAT". When
>>
>>the
>>
>>>species number is less, it can work well and it is quickly. But when the
>>>species number is more(example:2000), it told me"memory limit". So I
>>
>>change
>>
>>>"memory limit". But the speed is very slow. I took 13 hours to run the
>>>programe.
>>>Perhaps there are other methods that can do it. Or just change some
>>>parsmeters.
>>>who can help me?
>>>Thank you!
>>>                                                               Jian
>>
>>Zhang
>>
>>I don't have an example, but have you looked at ?Kenvl in the spatial
>>package?
>>
>>HTH,
>>
>>--sundar
>>
> 
> 
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