How to find distribution of the data?

Question

Sevil Cansu Yildirim 2020-1-29

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/502574-how-to-find-distribution-of-the-data

回答： Jemima Pulipati 2020-12-22

采纳的回答： Jemima Pulipati

all_velocities.txt

在 MATLAB Online 中打开

Hello,

I have a code that i calculate pairwise distances of points belonging to same grid on a map. Now, I want to know if those distances are very close to each other or not. In other words, I want to find if these distances in every grid are distributed normally, lognormally or not. I calculated the standard deviation of distances in every grid. But I dont know how to understand if my data is normally distributed in every grid or not.

Here you can find my code and data.

clear all;
addpath('D:\Desktop\BOUN\JOB\Slip_Rates\Slip_Data\MAP');
LAT1=39;LAT2=42;LON1=29.0;LON2=41.0;
sf = 1;
m_proj('albers equal-area','lat',[LAT1 LAT2],'long',[LON1 LON2],'rect','on');m_gshhs_h('color',[.5 .5 .5]);hold on; 
m_grid('linewi',1,'linest','none','tickdir','in','fontsize',10);
all = load('all_velocities.txt');
lon1=all(:,1);lat1=all(:,2);ve1=all(:,3);vn1=all(:,4);
% GRIDDING THE AREA
dLO = .5*2; dLA = .3636*2;
lon = [LON1:dLO:LON2];
lat = [LAT1:dLA:LAT2];
% DENSITY OF THE PLOTS & DISTANCES IN EVERY GRID
nlat = length(lat);
nlon = length(lon);
DIST = cell(nlat, nlon);
for i = 1:nlat
    for j = 1:nlon
        ind = find(abs(lat1-lat(i))<dLA/2 & (abs(lon1-lon(j))<dLO/2));    % FINDING ELEMENTS BELONGING O GRIDS
        DENSITY(i,j) = length(ind);                                       % WHICH GRID CONTAINS WHAT AMOUNT OF ELEMENT
        points = [reshape(lat1(ind),[],1), reshape(lon1(ind),[],1)];
        P{i,j} = points;
        DIST{i,j} = pdist(points, 'euclidean');                           % FINDING THE DISTANCE BETWEEN ELEMENTS BELONGING TO SAME GRID
    end
end
% STANDARD DEVIATION OF THOSE DISTANCES
for i = 1:nlat
    for j = 1:nlon
        SDIST(i,j) = std(DIST{i,j});
    end
end
% PLOT
m_pcolor(lon-dLO/2,lat-dLA/2,DENSITY);colormap(jet);colorbar;
m_quiver(lon1,lat1,sf.*ve1,sf.*vn1,1,'w','filled','AutoScale','off','linewidth',1.5);
hold off;

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Answer 1

Jemima Pulipati 2020-12-22

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/502574-how-to-find-distribution-of-the-data#answer_581570

Hello,

From my understanding you want to check if the given data is normally distributed or not.

The chi2gof(x) returns a test decision for the null hypothesis that the data in vector x comes from a normal distribution with a mean and variance estimated from x, using the chi-square goodness-of-fit test. The alternative hypothesis is that the data does not come from such a distribution. The result is 1 if the test rejects the null hypothesis at the 5% significance level, and 0 otherwise.

Some of the answers from the community which might be of relevance to you:

https://www.mathworks.com/matlabcentral/answers/45477-how-to-check-if-data-is-normally-distributed

https://www.mathworks.com/matlabcentral/answers/25129-normal-distribution-test