[R] Some unrelated questions.

[Harry Mamaysky]

R gives you facilities for doing this (using '...' and 'missing') without passing in a data.frame. For example,

> foo <- function(arg1,arg2,...) { if (missing(arg1)) cat('missing arg1\n'); print(list(...)) }
> foo(1,2,arg3=3,arg4=4,arg5=5)
$arg3
[1] 3
 
$arg4
[1] 4
 
$arg5
[1] 5
 
> foo(arg2=2,arg3=3,arg4=4,arg5=5)
missing arg1
$arg3
[1] 3
 
$arg4
[1] 4
 
$arg5
[1] 5
 
> 

Sent from my iPhone

On May 7, 2013, at 4:29 PM, Keith S Weintraub <kw1958 at gmail.com> wrote:

Jim,
  Thanks for your comments.
KW

--

On May 6, 2013, at 5:48 PM, Jim Lemon <jim at bitwrit.com.au> wrote:

> see inline
> 
> On 05/07/2013 02:14 AM, Keith S Weintraub wrote:
>> Folks,
>> 
>> I have been working on an R project that has a few dozen functions.
>> 
>> I have some questions that are only tangentially related and might only be a difference in style.
>> 
>> 1. Some of my functions take single-row data.frames as input parameters lists. I don't force the user of the function to provide all of the parameters. I use code within a function to test if a particular parameter (column-name) exists in the data.frame and if so use the value of that parameter in a test. If the parameter doesn't exist in the data.frame then some default behavior applies like so:
>> 
>>       if("rollDown" %in% names(runParams)) rollDown<-runParams[["rollDown"]]
>>      else rollDown<-0
>> 
>> Is this good style? What are the pitfalls? Is there a better way?
> Whether it is good style or not, you must have been reading my mind. This is more or less what I am working on to streamline the increasing number of arguments in functions in some of the packages I maintain. At the moment I am trying to work out whether it is easier to have one big function to complete all the arguments or a set of smaller functions for related groups of arguments.
> 
>> One nice thing about this method is that if I need to add a new parameter I don't have to change the signature of the function.
>> 
>> 2. What is a good way to organize a project with dozens of functions in R?
> Creating a package is an easy and well documented way of
> 
> 1) keeping all the functions together
> 2) checking that everything works
> 3) maintaining a record of the evolution of the project
> 
> Even a handful of functions can benefit from packaging.
> 
>> 3. My project involves a fair amount of simulation. I am not talking hours but some of my "runs" take up to 30 minutes.
>> 
>> Suppose I have a "control" function that calls a number of other functions that might benefit from compilation (using the compiler package). Is it better to compile the called functions inside or outside the control function?
>> 
>> Is there a good "idiom" or standardized way of turning compilation of the called functions on and off? What about debugging (I use the debug package)?
>> 
>> I am perfectly happy with pointers to articles, books and code.
> Jim

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