[R] A "rude" question

[Paul Gilbert]

Spencer Graves wrote:

> Hi, Paul:
>      How can I access "the package tests directory" you mentioned?  
> Only one of the 52 subdirectories of "library" in my current 
> installation of R 2.0.1 has a "test" folder. 

The tests directory seems to get stripped when you install a package. If 
you get a source package and untar it then there will be a tests 
directory in many packages (it is not required).

Paul

>
>      Thanks,
>      Spencer Graves   
> Paul Gilbert wrote:
>
>> One point that did not get mentioned in this discussion, and I 
>> believe deserves
>> much more publicity, is the impact of packages tests. The design of 
>> the package
>> system allows package developers to put tests in packages, and these 
>> are checked
>> regularly (see 
>> <http://cran.at.r-project.org/contrib/checkSummary.html>).
>>
>> These are intended to test the package functionality, but also give R 
>> what is
>> perhaps the largest test suite of any statistical software (certainly 
>> the most
>> quickly growing). While any single package's test will never 
>> guarantee that
>> the package works perfectly, the ensemble goes a long way toward 
>> ensuring
>> that core R functionality behaves as intended. It seems unlikely to 
>> me that any
>> commercial effort will ever be able to catch up.
>>
>> There are several ways that tests can add to our confidence that 
>> calculations can be trusted. They can
>>   - check against theoretical results
>>   - check against published results
>>   - check against results from other software
>>   - check that calculations done in different ways give the same result
>>   - check that monte carlo experiments give distributions that are 
>> consistent
>>      with expected results
>>
>> Some of these are relatively time consuming to set up and check the 
>> first time,
>> but after that they can be automatic.
>>
>> If you have particular calculations with specific packages that you 
>> are especially
>> concerned about, I encourage you to participate by devising good 
>> tests and sending
>> them to the package developers. (But first check the tests they are 
>> already doing
>> in the package tests directory.)
>>
>> Paul Gilbert
>>
>> msck9 at mizzou.edu wrote:
>>
>>> Dear all, I am beginner using R. I have a question about it. When 
>>> you use it,
>>> since it is written by so many authors, how do you know that the
>>> results are trustable?(I don't want to affend anyone, also I trust
>>> people). But I think this should be a question.
>>>
>>> Thanks,
>>> Ming
>>>
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>>
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>
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