[R] envelopes of simulations

[Adrian Baddeley]

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