Core area index calculation

Question

Core area index calculation

Closed this issue 5 years ago · 6 comments

I think there is perhaps some misunderstanding of how the Core Area Index (CAI) is supposed to be calculated and reported. As I understand it, the CAI is the ratio of the core to the perimeter area for each patch, and can be distinguished by class. But the documentation for the CAI function that determines the mean says that it has no upper limit. Given that it's a ratio, the upper limit should be 1, right? And sure enough, when I tried to calculate the CAI on a landscape with various classes of land cover, the mean CAI for one of my classes was calculated to be > 1.

mhesselbarth commented 5 years ago

86a657e

Answer 1 · 2019-11-08T16:44:09.000Z

Hey,

That seems to be a mistake in the documentation. The Core Area Index equals the percentage of a patch that is core area and has to be between 0% and 100%. Well...even 100% is not really possible since some cells have to be edge.

Following, the mean on class level has to have the same range as on patch level.

We will fix the documentation, thank you for pointing out.

Does that make sense to you?

Answer 2 · 2019-11-08T17:49:08.000Z

Hey Max, that does make sense to me. But to be clear: is the output supposed to be in terms of percentage, or is supposed to be the ratio between 0 and 1? Because when I ran it, I got back a value that was greater than 1, which should not be possible if the value is supposed to be between 0 and 1 unless there is some error with the code. Either way, thanks a bunch for writing this package! Super cool.

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On Fri, Nov 8, 2019 at 1:44 PM Maximilian Hesselbarth < ***@***.***> wrote: Hey, That seems to be a mistake in the documentation. The Core Area Index equals the percentage of a patch that is core area and has to be between 0% and 100%. Well...even 100% is not really possible since some cells have to be edge. Following, the mean on class level has to have the same range as on patch level. We will fix the documentation, thank you for pointing out. Does that make sense to you? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#138?email_source=notifications&email_token=AJ4QYZRXU4GFKVJSVY2HKRDQSWJNVA5CNFSM4JKX6GMKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEDSVURI#issuecomment-551901765>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJ4QYZW6OC3TAHBBOLNCYJ3QSWJNVANCNFSM4JKX6GMA> .

-- Jason Sauer PhD Candidate, Graduate Research Assistant School of Life Sciences Arizona State University Mail Code: 4601 *p: *913-424-5594 *email: *jason.sauer@asu.edu

Answer 3 · 2019-11-08T17:52:27.000Z

Sorry, I meant to attach an image of the outputs that I got from the CAI. On Fri, Nov 8, 2019 at 2:48 PM Jason Sauer <jason.robert.sauer@gmail.com> wrote:

…

Hey Max, that does make sense to me. But to be clear: is the output supposed to be in terms of percentage, or is supposed to be the ratio between 0 and 1? Because when I ran it, I got back a value that was greater than 1, which should not be possible if the value is supposed to be between 0 and 1 unless there is some error with the code. Either way, thanks a bunch for writing this package! Super cool. On Fri, Nov 8, 2019 at 1:44 PM Maximilian Hesselbarth < ***@***.***> wrote: > Hey, > > That seems to be a mistake in the documentation. The Core Area Index > equals the percentage of a patch that is core area and has to be between 0% > and 100%. Well...even 100% is not really possible since some cells have to > be edge. > > Following, the mean on class level has to have the same range as on patch > level. > > We will fix the documentation, thank you for pointing out. > > Does that make sense to you? > > — > You are receiving this because you authored the thread. > Reply to this email directly, view it on GitHub > <#138?email_source=notifications&email_token=AJ4QYZRXU4GFKVJSVY2HKRDQSWJNVA5CNFSM4JKX6GMKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEDSVURI#issuecomment-551901765>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/AJ4QYZW6OC3TAHBBOLNCYJ3QSWJNVANCNFSM4JKX6GMA> > . > -- Jason Sauer PhD Candidate, Graduate Research Assistant School of Life Sciences Arizona State University Mail Code: 4601 *p: *913-424-5594 *email: ***@***.***

-- Jason Sauer PhD Candidate, Graduate Research Assistant School of Life Sciences Arizona State University Mail Code: 4601 *p: *913-424-5594 *email: *jason.sauer@asu.edu

Answer 4 · 2019-11-08T18:13:15.000Z

I just double-checked to be sure, but the output is in percentage. So values larger than 1 are fine.

Answer 5 · 2019-11-08T18:26:00.000Z

Got it, thanks!

On Fri, Nov 8, 2019 at 3:13 PM Maximilian Hesselbarth < ***@***.***> wrote: I just double-checked to be sure, but the output is in percentage. So values larger than 1 are fine. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#138?email_source=notifications&email_token=AJ4QYZWS73SSEXTWNIGAUYTQSWT3ZA5CNFSM4JKX6GMKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEDS5PVQ#issuecomment-551933910>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJ4QYZVTLAYM2R7IT7ILUILQSWT3ZANCNFSM4JKX6GMA> .

-- Jason Sauer PhD Candidate, Graduate Research Assistant School of Life Sciences Arizona State University Mail Code: 4601 *p: *913-424-5594 *email: *jason.sauer@asu.edu