envelopes of simulations

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envelopes of simulations

Adrian Baddeley-2

Sara Mouro writes:
 > Hello!
 >
 > I am writing you because I could not plot the confidence envelopes for
 > functions Jest, Jcross, Jdot, Jmulti, and L, using the Spatstat package.

Enquiries about a package should be sent to the package maintainer
rather than R-help.

 > I have already understood how to do that for Kest or Jest, that is:
 > JEnv <- plot(envelope(PPPData, Jest))
 > Where PPPData is my ppp object.
 >
 > However, for Jcross I must specify the two marks I want to analyse.
 > That is, usually I would get the Jcross doing:
 > Jc <- Jcross(PPPData,"Aun","Qsu")
 > For marks "Aun" and "Qsu".

To do this, type
      envelope(PPPData, Jcross, i="Aun", j="Qsu")

Explanation:
        Looking at help(Jcross) we see that its formal syntax is
                Jcross(X, i, j).
        This means that when you call
                Jcross(PPPData,"Aun","Qsu")
        the arguments are matched as
                Jcross(X=PPPData,i="Aun",j="Qsu").

        So our problem is, how to pass the arguments i="Aun" and j="Qsu"
        to the function Jcross each time it is called by `envelope'.

        The help entry for 'envelope' mentions that `envelope' will accept
        extra arguments "..." which are then passed to the function 'fun'.
       
        So, to pass the two argument values i="Aun" and j="Qsu",
        just type
             envelope(PPPData, Jcross, i="Aun", j="Qsu")

 > For L function, I can make:
 > K <- Kest (PPPData, correction="isotropic")
 > plot (K, r-sqrt(iso/pi)~r)

        You can compute the envelope for the K-function
        and transform it afterwards.

        To plot envelopes of the L function discrepancy
           LD(r) = sqrt(K(r)/pi) - r,
        just type
                E <- envelope(PPPData, Kest, correction="isotropic")
                plot(E, sqrt(./pi) -r ~ r)

Hope this helps.
regards
Adrian Baddeley

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