Many thanks for this, David. It is applicable, indeed! Thank you for sharing
the search function as well.
Have a good day!
Ana
>________________________________
>From: David Winsemius <dwinsem...@comcast.net>
>To: Ana Kolar <annako...@yahoo.com>
>Cc: R <r-help@r-project.org>
>Sent: Monday, 18 July 2011, 17:22
>Subject: Re: [R] SDMTools package - calculating overlap?
>
>
>On Jul 18, 2011, at 11:07 AM, Ana Kolar wrote:
>
>> Dear David,
>>
>> The toy example doesn't represent functions as such, but represents type of
>> data that I'm operating with. These data are product of an analysis. If I
>> understand you correctly, I would need to approximate distribution functions
>> of these data first and then integrate. This makes sense, but any
>> suggestion/ideas of how to do it in R?
>
>Here's the deal.... posters are expected to read the Posting Guide and make
>good faith efforts at applying the information they get to their data using
>the help page information. In there you should find that the expectations on
>posts includes you providing as complete a description as will be needed to
>address the question. Data, code and error messages.... all should be included.
>
>I also see no evidence that you have made any such attempt to use any of the
>functions I have pointed you to. The Posting Guide imposes a responsibility
>that you will consult the archives. There are tons of worked examples in the
>archives of using `stepfun` or `approxfun` together with `integrate`.
>
>RSiteSearch used to search the archives for you but they changed it in recent
>years, so I now use a modified version of it:
>
>rhelpSearch <- function(string,
> restrict = c("Rhelp10", "Rhelp08", "Rhelp02", "functions" ),
> matchesPerPage = 100, ...)
> RSiteSearch(string=string, restrict = restrict,
> matchesPerPage = matchesPerPage, ...)
>
>Try this:
>
>rhelpSearch("approxfun integrate")
>
>The answer by Lumley in the first ten itmes) looks directly applicable.
>
>--David.
>>
>> Many thanks!
>>
>> Best regards,
>>
>> Ana
>>
>> From: David Winsemius <dwinsem...@comcast.net>
>> To: Ana Kolar <annako...@yahoo.com>
>> Cc: R <r-help@r-project.org>
>> Sent: Monday, 18 July 2011, 16:41
>> Subject: Re: [R] SDMTools package - calculating overlap?
>>
>>
>> On Jul 18, 2011, at 10:11 AM, Ana Kolar wrote:
>>
>> > Yes, indeed! I believe I should integrate differences of min of both
>> > functions, no? I'm not quite sure how this should be done in R therefore I
>> > was wondering if there are some build in functions that do this job
>> > already. If not I would appreciate any help of how should it be done
>> > otherwise.
>>
>> ?integrate # would seem to be the glaringly obvious help query
>>
>> >
>> > Toy example of data is here:
>> >
>> > a <- matrix(runif(30))
>> > b <- matrix(runif(30))
>>
>> That's not a well-defined example of functions even if we take the index to
>> be the x value. Presumably you have some sort of value in mind for "a" at an
>> x-value of 1.5 but it is not clear from what you have presented.
>>
>> ?stepfun
>> ?approxfun
>>
>>
>> A function takes inputs (on some continuous measurement scale) and returns
>> results. Perhaps you should be seeking some local mathematical/statistical
>> consulting resource.
>>
>> --David.
>>
>> >
>> > I tried to calculate this overlap with "Istat" function but am not sure
>> > that it does the job right! This is the example:
>> >
>> > library(SDMTools)
>> > a <- matrix(runif(30))
>> > b <- matrix(runif(30))
>> > Istat(a,b)
>> >
>> > Many thanks for your response, David!
>> >
>> > Ana
>> >
>> >
>> >
>> > From: David Winsemius <dwinsem...@comcast.net>
>> > To: Ana Kolar <annako...@yahoo.com>
>> > Cc: R <r-help@r-project.org>
>> > Sent: Monday, 18 July 2011, 15:45
>> > Subject: Re: [R] SDMTools package - calculating overlap?
>> >
>> >
>> > On Jul 18, 2011, at 9:40 AM, Ana Kolar wrote:
>> >
>> > > Dear R users,
>> > >
>> > > Any idea of how to calculate an area of an overlap between two
>> > > functions? The only R build in function that I found is I Similarity
>> > > Statistic for Quantifying Niche Overlap and I am really not sure if this
>> > > function is producing exactly what I am interested in since I was
>> > > plotting functions and often got confused results (for example: got high
>> > > value for the overlap of one pair and low for the other pair, while from
>> > > the plot it looked like the first pair was overlapping better.) Can
>> > > anyone please explain what's the reason behind such a behaviour? And
>> > > does anyone has a suggestion of what function could be used for a
>> > > calculation of an overlap area? The problem with 'Istat' function is
>> > > also that it requires both data sets to have the same length, while I
>> > > would be more interested in a function that enables overlap calculation
>> > > even if data sets have different length. Looking forward to hearing from
>> > > you! Have a good day. Ana
>> >
>> > Shouldn't you be integrating their difference (or the absolute value of
>> > their differences depending on your definition of "overlap"). I fail in
>> > understanding your example. Where is/are the function(s)?
>> >
>> > >
>> > > library(SDMTools)
>> > > a <- matrix(runif(30))
>> > > b <- matrix(runif(30))
>> > > Istat(a,b)
>> > > [[alternative HTML version deleted]]
>> > --
>> > David Winsemius, MD
>> > West Hartford, CT
>> >
>> >
>> >
>>
>> David Winsemius, MD
>> West Hartford, CT
>>
>>
>>
>
>David Winsemius, MD
>West Hartford, CT
>
>
>
>
[[alternative HTML version deleted]]
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