[R] fitdistr for t distribution
spencerg
spencer.graves at prodsyse.com
Sun May 17 02:13:30 CEST 2009
In addition to seeing the code by typing the name of the function
(and copying it from there into a file), you can also enter
"debug(fitdistr)", for example. Then the next time you use "fitdistr",
either directly or indirectly, it puts you in the environment of that
function, and you can walk through it line by line, examining objects,
changing them, etc.
To get the code for an S3 generic function like "predict", use the
"methods" function, followed, e.g., by "getAnywhere".
Hope this helps.
Spencer Graves
Paul Johnson wrote:
> On Fri, May 15, 2009 at 6:22 AM, lagreene <lagreene101 at gmail.com> wrote:
>
>> Thanks Jorge,
>>
>> but I still don't understand where they come from. when I use:
>> fitdistr(mydata, "t", df = 9) and get values for m and s, and the variance
>> of my data should be the df/s?
>>
>> I jsut want to be able to confirm how m and s are calculated
>>
>
> I've wondered the same kind of thing and I've learned the answer is
> easy! It is not so easy for all R functions, but did you try this
> with fitdistr?
>
>
>> library (MASS)
>> fitdistr
>>
>
> the output that follows is the ACTUAL FORMULA that is used to make the
> calculations!
>
> I've not yet mastered the art of getting code for some functions.
>
>
>> predict
>>
> function (object, ...)
> UseMethod("predict")
> <environment: namespace:stats>
>
> But I know there is a way to get that code if you know the correct way
> to run getS3method(). But I usually just go read the R source code
> rather than puzzle over that.
>
>
>
>
>> mydt <- function(x, m, s, df) dt((x-m)/s, df)/s
>> fitdistr(x2, mydt, list(m = 0, s = 1), df = 9, lower = c(-Inf, 0))
>>
>> Thanks anyway for the help!
>>
>
>
More information about the R-help
mailing list