FWIW: I have put the (slightly updated) sheet at
http://r.research.att.com/man/R-API-cheat-sheet.pdf
Note that it is certainly incomplete - but that is intentional to a) to fit the
space constraints and b) to show only the most basic things since we are
talking about starting with .Call -- advanced users may need a different sheet
but then they just go straight to the headers anyway ...
Cheers,
Simon
On Mar 27, 2012, at 12:20 PM, Simon Urbanek wrote:
>
> On Mar 27, 2012, at 12:03 PM, Terry Therneau wrote:
>
>> On 03/23/2012 10:58 AM, Simon Urbanek wrote:
>>> This is my shot at a cheat sheet.
>>> comments are welcome.
>>>
>>> Simon
>>>
>>>
>> I was looking through the cheat sheet. It's nice. There are a few things
>> in it that I can't find in the documentation though. Where would one find a
>> description? (I can guess, but that may be dangerous).
>>
>> mkNamed
>
> It is a shorthand for using allocVector and then setting names (which can be
> tedious). It's a simple way to create a result list/object (a very common
> thing to do):
>
> SEXP res = PROTECT(mkNamed(VECSXP, (const char*[]) { "foo", "bar", ""}));
> // fill res with SET_VECTOR_ELT(res, ..)
> setAttrib(res, R_ClassSymbol, mkString("myClass"));
> UNPROTECT(1);
> return res;
>
> Note that the sentinel is "" (not not NULL as commonly used in other APIs).
> Also you don't specify the length because it is determined from the names.
>
>
>> R_Naint (I don't see quite how this differs from using NA_INTEGER to set a
>> result)
>
> It doesn't really -- NA_INTEGER is defined to be R_NaInt. In theory
> NA_INTEGER being a macro could be a constant instead -- maybe for efficiency
> -- but currently it's not.
>
>
>> R_PreserveObject, R_ReleaseObject (Advantages/disadvantages wrt PRESERVE?)
>>
>
> I guess you mean wrt PROTECT? Preserve/Release is used for objects that you
> want to be globally preserved - i.e. they will survive exit from the
> function. In contrast, the protection stack is popped when you exit the
> function (both by error or success).
>
> Cheers,
> Simon
>
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