[Scilab-users] spatial correlation coefficient: Is the MATLAB corrcoef function doing the job?

[Heinz]

Thanks for the many pointers. At this stage, although R is installed on my
computer, I would hesitate learning R just to run the Nathan Mantel test.
Can someone give me a helping hand in defining a spatial coordination index?
Using - in the first place - the random xyz coordinates below that we had
been using before for the nearest neighbour distribution which had worked
out very well in accordance theoretical predictions.

Apllication of covariance/correlance analysis turned out to be useless,
because this investigates a search into linear dependencies of the x, y, z
vectors and this is not of interest.

Now, with the numbers generated below, the spatial coordination index
looking for clusters and holes in 3d space should come out near zero.
Somebody trying to run the numbers?

For an xy projection, see <
https://www.dropbox.com/s/0sv1ak9zwk5f8rv/16%2C867%20points%20in%203d%20spac
e.pptx?dl=0>.

Heinz

// START OF CODE FOR RANDOM x, y, z NUMBER GENERATION
n=16867;
r=25046;
radius = r*grand(n,1,'def').^(1/3); 
phi = 2*%pi*grand(n,1, 'def'); 
costheta = 1 - 2*grand(n,1, 'def'); 
radsintheta = radius.*sin(acos(costheta));
x=radsintheta.*cos(phi);
y=radsintheta.*sin(phi);
z=radius.*costheta;
// END OF CODE 

-----Original Message-----
From: users [mailto:users-bounces at lists.scilab.org] On Behalf Of Stéphane
Mottelet
Sent: 09 February 2018 09:47
To: Users mailing list for Scilab <users at lists.scilab.org>
Subject: Re: [Scilab-users] spatial correlation coefficient: Is the MATLAB
corrcoef function doing the job?

Hello,

There seems to be some statistical tests related to this, namely Moran’s or
Mantel tests :

https://stats.idre.ucla.edu/other/mult-pkg/faq/general/faq-how-can-i-detecta
ddress-spatial-autocorrelation-in-my-data/

http://www.petrkeil.com/?p=1050

hth

S.


Le 08/02/2018 à 20:16, Heinz a écrit :
> Sorry, I am lost.
>
> I have 10,000 xyz data and want to know, if there is some regularity 
> in them or if they are more or less random. The concept of a mask does 
> not come up at all...
> Best greetings
> Heinz
>
> What do you suggest should be used here?
>
> -----Original Message-----
> From: users [mailto:users-bounces at lists.scilab.org] On Behalf Of 
> Samuel Gougeon
> Sent: 08 February 2018 19:19
> To: Users mailing list for Scilab <users at lists.scilab.org>
> Subject: Re: [Scilab-users] spatial correlation coefficient: Is the 
> MATLAB corrcoef function doing the job?
>
> Hello Heinz,
>
> Le 07/02/2018 à 23:13, Heinz a écrit :
>> Friends:
>>
>> I need to compute the spatial correlation coefficient of my x,y,z 
>> data in
> 3d.
>> Question 1: Is the MATLAB corrcoef function doing the job?
>> Question 2: How do I get corrcoef running in SciLab or C?
> Do you mean the autocorrelation of a data(x,y,z) sampled distribution?
> Or the intercorrelation of data(x,y,z) with a mask(x,y,z) function 
> sampled on the same grid?
> Or anything else?
>
> Samuel
>
>
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> users at lists.scilab.org
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