How to find duplicated values and calculate the mean of them?

I have a data set of points that consist latitudes, longitudes and respectively velocities. I need to find the same points (same latitudes and longitudes), but need to take the average of their velocities. So my new data set will consist no duplicates but instead averaged velocity values of those duplicants. But I dont know how can I find the duplicated values and how to merge them with non duplicated ones.

You can find my code and data here;

clear all;
a = load('all_velocities.txt');

A = [a(:,1) a(:,2)];  % latitude and longitudes

k=1;
for i = 1:length(A)
    [U, ia] = unique(A, 'rows'); %unique values
    DATA(k,:) = [U(ia,1) U(ia,2) a(ia,3) a(ia,4)]; % new data set with unique lat and lon and their velocities
    k=k+1; 
end

So far I ended up with this error message:

Index in position 1 exceeds array bounds (must not exceed 385).

Error in duplicate (line 9)

DATA(k,:) = [U(ia,1) U(ia,2) a(ia,3) a(ia,4)];

Also I need to calculate the average velocity of those duplicated ones and merge them with data.

Answer 1

[Stephen23]

Here is one solution:

>> M = dlmread('all_velocities.txt');
>> [~,~,X] = unique(M(:,1:2),'rows');
>> F = @(x) mean(M(x,:),1);
>> Data = arrayfun(F,1:max(X),'UniformOutput',false));
>> Data = vertcat(Data{:});

Another option would be to use a table:

https://www.mathworks.com/help/matlab/matlab_prog/grouping-variables-for-splitting-data.html

[Sevil Cansu Yildirim]

I am sorry but when I plot data with this code, I still can see the duplicates.

clf; clear all;

% PLOT FAULT
name = 'faults_Turkey.dat';file = fopen(name,'r'); kk   = 1;
for j = 1:31000;lin=fgetl(file);
 if j ~=1 && lin(1)=='>';plot(flon,flat,'color',[.5 .5 .5],'linewidth',1.5);hold on;clear flat flon;kk=1;else;  aa=str2num(lin);flat(kk)=(aa(2));flon(kk)=(aa(1));kk=kk+1;end
end; fclose(file); axis([29 41 39 43]);

% PLOT GPS MEASUREMENTS

a = load('data.txt'); 
% [g1,g2] = ginput(6)

g1 = [33.8216   33.8667   33.2100   32.8776   32.6724   32.2497   31.9624   31.5396   30.75   30.1688   29.9924   30.0252   31.8310   33.6492   33.8626];
g2 = [42.0680   41.0975   40.9645   40.9220   40.8635   40.7970   40.7678   40.6534   40.55   40.6960   40.9592   41.5814   41.8154   42.0414   42.0440];

g3 = [34.1628   34.4537   35.3196   36.0202   36.1656   36.3441   35.4187   34.6982   33.7068   33.6605   33.6605   33.6671   33.7927   34.0835   34.1496];
g4 = [41.1302   41.1259   41.1173   41.0060   41.1558   42.0123   42.1279   42.1236   41.9138   41.6183   41.3014   41.0873   41.0659   41.1216   41.1302];

g5 = [39.9429   40.2854   40.8503   40.51   39.1738   37.4733   36.5058   36.3136   35.9951   36.4998   37.1548   38.1403   38.6931   39.4382   39.9189];
g6 = [39.6122   39.7212   40.4336   41.10   41.2901   41.6210   41.8195   41.8779   40.9086   40.6944   40.4414   40.2039   40.0404   39.8224   39.6161];

g7 = [33.5738   33.2866   32.8638   32.5027   31.3863   30.9061   30.4054   30.3439   30.4301   31.5382   32.8433   33.6764   33.6518   33.6436   33.6272];
g8 = [40.9950   40.9472   40.8700   40.8222   40.6015   40.5483   40.4499   39.9102   39.3358   39.4316   39.6496   39.8304   40.3143   40.7291   40.9711];

g9 = [33.6022   33.6433   35.9192   35.9864   35.6096   35.4230   35.2327   34.9865   34.6357   34.4641   34.3708   34.2141   33.9604   33.7403   33.6097];
g10 =[41.0202   39.8261   39.6521   40.8800   41.0178   41.0372   41.0589   41.0686   41.0686   41.0710   41.0662   41.0613   41.0565   41.0396   41.0227];

g11 = [40.1190   39.4640   38.5086   35.8827   35.9908   36.5016   36.8080   37.1746   37.6613   38.0639   38.6528   39.3378   39.7524   39.9327   40.1129];
g12 = [39.4853   39.0026   39.0142   39.6488   40.8790   40.6376   40.5481   40.3807   40.2911   40.1977   40.0186   39.8434   39.6644   39.5748   39.4736];

[in]=inpolygon(a(:,1),a(:,2),g1,g2);lonN = a(in,1);latN = a(in,2);veN = a(in,3);vnN = a(in,4);
quiver(lonN,latN,veN,vnN,'b');

[in]=inpolygon(a(:,1),a(:,2),g3,g4);lonN = a(in,1);latN = a(in,2);veN = a(in,3);vnN = a(in,4);
quiver(lonN,latN,veN,vnN,'g');

[in]=inpolygon(a(:,1),a(:,2),g5,g6);lonN = a(in,1);latN = a(in,2);veN = a(in,3);vnN = a(in,4);
quiver(lonN,latN,veN,vnN,'k');
 
[in]=inpolygon(a(:,1),a(:,2),g7,g8);lonN = a(in,1);latN = a(in,2);veN = a(in,3);vnN = a(in,4);
quiver(lonN,latN,veN,vnN,'color',[.61 .51 .74]);

[in]=inpolygon(a(:,1),a(:,2),g9,g10);lonN = a(in,1);latN = a(in,2);veN = a(in,3);vnN = a(in,4);
quiver(lonN,latN,veN,vnN,'c');

[in]=inpolygon(a(:,1),a(:,2),g11,g12);lonN = a(in,1);latN = a(in,2);veN = a(in,3);vnN = a(in,4);
quiver(lonN,latN,veN,vnN,'m');

line(g1,g2,'Color','blue','LineStyle','--');
line(g3,g4,'Color','green','LineStyle','--');
line(g5,g6,'Color','black','LineStyle','--');
line(g7,g8,'Color',[.61 .51 .74],'LineStyle','--');
line(g9,g10,'Color','cyan','LineStyle','--');
line(g11,g12,'Color','magenta','LineStyle','--');

[Stephen23]

@Sevil Cansu Yildirim: your comment shows some unrelated code which uses different data files to the one you provided in your question. I have no idea how your comment relates to your question or to my answer.

[Sevil Cansu Yildirim]

here i load the data you reduced for me (duplicates are averaged)

a = load('data.txt');

this code is just something i use for plotting the data. when i plot matrix a, it is the arrows at the figure in the end. and you can see duplicated arrows.