R help - Oct 2005 - Sum of logical vector

Hi,

Recently I was told by users of some of the function I wrote that they
experience crashes in places where logical vector was passed to sum
function. However on my computer those functions work just fine. After
closer look at documentation of function 'sum', I realized that it is
defined only for complex and numeric vectors, so I guess I was using
"undocumented feature". 

What I am trying to understand is why it works on some systems (my - Win XP,
from R-1.9.? to R-2.2.0) and does not work on other (unknown platform,
R-2.2.0):
- Is it that they have more methods of function "sum" defined and some
other
function (maybe some package has "logical.sum" defined) is being used?
- Different operating systems will have different behavior for supporting
"undocumented features"?

Is there any way to automatically test your code for presence of unsupported
functions it uses?
Should function 'sum' produced warning/error, or convert logical to
integer?

An Example code:

 repeats = function(x) return (sum(duplicated(x)) ) # how many numbers
repeat themselves in vector x?
 repeats( c(1:10, 3:14) )

 Jarek 
====================================================\==== 
 Jarek Tuszynski, PhD.                           o / \ 
 Science Applications International Corporation  <\__,|  
 (703) 676-4192                                   ">  \ 
 Jaroslaw.W.Tuszynski at saic.com                     `   \

On 10/31/2005 2:00 PM, Tuszynski, Jaroslaw W. wrote:
> Hi,
> 
> Recently I was told by users of some of the function I wrote that they
> experience crashes in places where logical vector was passed to sum
> function. However on my computer those functions work just fine. After
> closer look at documentation of function 'sum', I realized that it
is
> defined only for complex and numeric vectors, so I guess I was using
> "undocumented feature". 
> 
> What I am trying to understand is why it works on some systems (my - Win
XP,
> from R-1.9.? to R-2.2.0) and does not work on other (unknown platform,
> R-2.2.0):
> - Is it that they have more methods of function "sum" defined and
some other
> function (maybe some package has "logical.sum" defined) is being
used?
> - Different operating systems will have different behavior for supporting
> "undocumented features"?
> 
> Is there any way to automatically test your code for presence of
unsupported
> functions it uses?
> Should function 'sum' produced warning/error, or convert logical to
integer?
> 
> An Example code:
> 
>  repeats = function(x) return (sum(duplicated(x)) ) # how many numbers
> repeat themselves in vector x?
>  repeats( c(1:10, 3:14) )
You should always be able to sum a logical vector, because it will be 
coerced to numeric when needed.  The crashes are being caused by 
something else. Get your users to tell you exact error messages and you 
should be able to diagnose it.

Duncan Murdoch