[ncl-talk] A useful tidbit about kmean clustering

[Barry Lynn]

Hi:

I had a couple of problems running the code.

1) It is not obvious how to set the k_clst (how many cluster), especially
when running from a script.

2) I really wanted to see the members of each cluster.

Here, I do the following (in the Excerpt):

1) Set the number of clusters to 1 less than the number of points.
Otherwise, the program produces zeros or undefined numbers. or just strange
answers.
2) I then reduce the number of clusters until I have just a  cluster with 1
grid point, inclusive (or the minimum number of points).
3) Because I didn't know how to modify the call to the clustering program,
I created my own from the fortran file, which outputs the members of each
cluster.
4) I use WRAPIT it to call this program

I have attached a self-contained fortran version of the code.

Barry



On Sun, Jan 19, 2020 at 5:30 PM Barry Lynn <barry.h.lynn at gmail.com> wrote:

> Hi:
>
> Thank you for asking.
>
> I found the FORTRAN code and may pass on my modifications if warranted.
>
> Thanks
>
> On Sun, 19 Jan 2020 at 17:26 Dennis Shea <shea at ucar.edu> wrote:
>
>> I am not sure of the question.
>> ---
>> You would have to access the changed code via a 'shared object'
>>
>> Does it require additional arguments? The NCL version of 'kmns' uses
>> double precision arguments.
>>
>> C NCLFORTSTART
>>       subroutine *kmns136* (dat, m, n, clcntr, k,  ic1, nc
>>      +                   ,iter, iseed, wss, ier)
>>       implicit none
>> c                            ! INPUT
>>       integer m, n, k, iter, iseed
>>       double precision dat(m,n)
>> c                            ! INPUT/OUTPUT
>>       integer ic1(m), nc(k), ier
>>       double precision clcntr(n,k), wss(k)
>> C NCLEND
>> c                            ! LOCAL WORK ARRAYS
>>       integer          ic2(m), ncp(k), itran(k), live(k)
>>       double precision an1(k), an2(k), d(m)
>>       integer nv, kk, mm
>> ====
>>
>> Change: * kmns136* to (say) kmns136x
>>
>> Then use WRAPIT to generate the shared object
>>
>>
>>
>>
>>
>> On Sun, Jan 19, 2020 at 4:04 AM Barry Lynn via ncl-talk <
>> ncl-talk at ucar.edu> wrote:
>>
>>> Hello:
>>>
>>> I would like to use cluster analysis and it would be very helpful (I
>>> hope) if I could modify the source code.
>>>
>>> I downloaded the NCL source code from here:
>>>
>>> https://www.earthsystemgrid.org/dataset/ncl.640.src/file.html
>>>
>>> and found the Fortran (.f) programs in this directory.
>>>
>>> NCL_SOURCE/ncl_ncarg-6.4.0/ni/src/lib/nfpfort
>>>
>>> Barry
>>> --
>>> Barry H. Lynn, Ph.D
>>> Senior Associate Scientist, Lecturer,
>>> The Institute of the Earth Science,
>>> The Hebrew University of Jerusalem,
>>> Givat Ram, Jerusalem 91904, Israel
>>> Tel: 972 547 231 170
>>> Fax: (972)-25662581
>>>
>>> C.E.O, Weather It Is, LTD
>>> Weather and Climate Focus
>>> http://weather-it-is.com
>>> Jerusalem, Israel
>>> Local: 02 930 9525
>>> Cell: 054 7 231 170
>>> Int-IS: x972 2 930 9525
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> ncl-talk at ucar.edu
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>
>> --
> Barry H. Lynn, Ph.D
> Senior Associate Scientist, Lecturer,
> The Institute of the Earth Science,
> The Hebrew University of Jerusalem,
> Givat Ram, Jerusalem 91904, Israel
> Tel: 972 547 231 170
> Fax: (972)-25662581
>
> C.E.O, Weather It Is, LTD
> Weather and Climate Focus
> http://weather-it-is.com
> Jerusalem, Israel
> Local: 02 930 9525
> Cell: 054 7 231 170
> Int-IS: x972 2 930 9525
>
>

-- 
Barry H. Lynn, Ph.D
Senior Associate Scientist, Lecturer,
The Institute of the Earth Science,
The Hebrew University of Jerusalem,
Givat Ram, Jerusalem 91904, Israel
Tel: 972 547 231 170
Fax: (972)-25662581

C.E.O, Weather It Is, LTD
Weather and Climate Focus
http://weather-it-is.com
Jerusalem, Israel
Local: 02 930 9525
Cell: 054 7 231 170
Int-IS: x972 2 930 9525
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