[R] calculate quantiles of a custom function

[Gerhard]

Am Dienstag, 3. Januar 2012, 11:05:11 schrieben Sie:
> 
> The quick way is to look at the structure with 'str':
> 
> str(integrate(myfunction,0,.9))
> List of 5
>   $ value       : num 1.85
>   $ abs.error   : num 2.05e-14
>   $ subdivisions: int 1
>   $ message     : chr "OK"
>   $ call        : language integrate(f = myfunction, lower = 0, upper
> = 0.9)
>   - attr(*, "class")= chr "integrate"
> 
> The longer way would be to look at the help)integrate)  page where the
> "Value" section would have told you that a list with named components
> 
> was returned:
>  > integrate(myfunction,0,.9)$value
> 
> [1] 1.850299
> 
> In this instance you could also probably use 'cumsum' (which is just
> doing the numerical integration by hand
> 
> plot(cumsum( myfunction(seq(0,1,by=0.001)))/
> sum(myfunction(seq(0,1,by=0.001)) ) )


Thanks a lot; now I now where I need to look for help before bothering you 
again. 

Best,

Gerhard

> 
> > I need to hand on the value to another function, and then I get an
> > error
> > message, because the output of integrate is not a numerical argument.
> > 
> >>> I have not seen any continous function treated in the docs, and
> >>> applying the
> >>> "quantile function" gives me an error (since it seems only to be
> >>> defined on
> >>> lists and atoms).
> >> 
> >> There is also a family of packages, all of whose names begin with
> >> "distr". They provide a variety of facilities for developing new
> >> distributions, both discrete and continuous.
> > 
> > That looks quite frightening. But if it turns out to be necessary.
> 
> But a good way to improve you knowledge of statistical concepts.
> 
> > Thank you,
> > 
> > Gerhard
> 
> David Winsemius, MD
> West Hartford, CT