similar to: Lazy Evaluation?

I recently encountered this and was wondering if someone could explain what happened. Basis of question involves what the difference between the calls makes as the end result is the same: > identical(matrix(1:8, nrow = 1), array(1:8, c(1, 8))) TRUE If I run the code below as shown, I get the following: > foo(1:8, 4) foo (vector, numeric) val = 4 foo (matrix, ANY) val = 500 foo

Dear all, This problem came up initially while debugging a function, but it seems to be a more general problem of R. I hope I'm wrong, but I can't find another explanation. Let me illustrate with the raster package. For an object "RasterLayer" (which inherits from Raster), there is a method xyValues defined with the signature

I have classes A and B, where B contains A. In the implementation of the group generic for B I would like to use the corresponding group generic for A. Is there a way to do that? I would also appreciate any comments if what I'm trying to do seems like the wrong approach. Here's a stripped down example: setClass("A",

There seems to be an issue with passing "..." to callGeneric(), because it assumes that the call can be evaluated in the parent frame. Due to lazy evaluation, that is often not going to work for arguments that are simply passed down via "...". Here is an example: setClass("A", contains = "character") setClass("B", contains =

Folks: This is a question about the S4 formal class system. Suppose I have a class, 'foo', defined by: setClass('foo',representation(dat='matrix', id='character') ) I wish to define a '[' method for foo that will extract from the 'dat' slot. I would have thought that the following would work, but it doesn't:

What a delicious example! (I'm taking the liberty of sharing it with r-devel, since it raises some good issues.) You have two questions, presumably: 1 - how could the order of the setMethod calls make a difference in the results? 2 - what's causing the infinite loop & how could it be avoided, reliably? Second question first. The danger sign is the "vector" method:

I have some code where the primary dispatching is on other parameters so I'd like not to have to create a set of functions for "matrix" and another duplicate set for "array". But the class union technique isn't working as implemented below and I don't have my Green book with me. How do I fix my infinite recursion problem?

Hi, I found the following on Windows 2000/NT R Version 1.9.1 (2004-06-21) (also Version 1.9.0): The S4 group "Math" doesn't work as documented; i.e., "log", "log10", "gamma" and "lgamma" are included in the documentation but don't work. See example code below. Moreover, what about 'genericForPrimitive' which is used in

Is it possible for S4 to (continue) dispatch to a class created during dispatching? The code below doesn't work; is this not possible or have I ommitted something? Concept was to create a SEXP with R_AllocatePtr, give it a class attribute, and continue dispatch. Example code below omits multiple parameters that can be different types. Essentially, any parameter would be converted to an

Hi I am having difficulty with setMethod(). I have a "brob" class of objects whose representation has two slots: "x" and "positive". Slot "x" (double) holds the log of a number and slot "positive" (logical) its sign. The idea is that large numbers can be handled. I'm trying to implement a log() method using an analogue of the

Hello. This question concerns the Methods package. I have created a new class and am trying to set a method for it for S4 group generic "Summary". I have run into some signature problems. An example: > setClass("track", representation(x="numeric", y="character")) [1] "track" > setGeneric("max", group="Summary")

Hello, the last command (isGeneric) in following R-code (attached) produces different output, depending on wheter 1.8.0 alpha or 1.7.1 is used. Is that to be expected ? Both R Versions were started with option vanilla --------------------------------------------------- R.1.7.1: --------------------------------------------------- > version _ platform i686-pc-linux-gnu arch i686

Hi, we have some questions concerning the definition of new arithmetic methods. In our package "distr" (on CRAN) we define some new arithmetic methods for "+", "-", "*", "/". After loading "distr" the corresponding arithmetic methods work. Now, if we define a new class and also a new method for one of the arithmetic methods

The Complex group generic for S4 methods is not working: > setClass('foo', representation(z='complex')) [1] "foo" > setMethod('Complex', 'foo', function(z) callGeneric(z@z)) [1] "Complex" > Arg(new('foo', z=1+0i)) Error in Arg(new("foo", z = 1 + (0+0i))) : non-numeric argument to function > The fix is

Dear list, It seems that S4 methods defined for an S3 'base' generic are not used in 'base' functions. This can be problematic when 'base' functions start with something like 'as.matrix'. ### START R code setClass("classA", contains = "matrix", representation(realData = "numeric")) setMethod("as.matrix",

I get an error when using self-defined (not standard) functions with mapply with S4 objects from the raster package that I develop: "Error in as.character(sys.call(sys.parent())[[1]]) : cannot coerce type 'closure' to vector of type 'character'". Does anyone understand why? The problem is illustrated below. Thanks, Robert > # First a general example that works

Hello, I have defined a new class > setClass("myclass", representation(min = "numeric", max = "numeric")) and want to write accessor functions, so that for > foo = new("myclass", min = 0, max = 1) > min(foo) # prints 0 > max(foo) # prints 1 At first i created a generic function for "min" > setGeneric("min",

Dear all, In R-devel I have noticed the new approach for the "ts" class in the package "methods". the "structure" behaviour of "ts" is not always kept when one uses "ts" objects and objects of classes which extend the virtual class "structure". As a short example: ## this works fine setClass("foo", representation(header =

I've recently come across two pieces of code using calls to callGeneric() inside the definition of a method. In both cases, it appears to me that the callGeneric call could be replaced with a "real" call to the generic, say foo(x) instead of callGeneric(x) inside method foo. My understanding from the docs is that when called with arguments, it is just like calling the actual

Hi the list I define a class A (slot a and b), a class C (slot c and d) and a class E that inherit from A and B. I define print(A) and print(B). For print(C), I would like to use both of them, but I do not see how... Thanks for your help... Christophe ---------------------------------------------------------------- Ce message a ete envoye par IMP, grace a l'Universite Paris 10 Nanterre