MATLAB: Checkin for equal values in the same column

Question

Hi

I have a matrix with measured GPS points. Column 1 are the point number, column 2-4 are X,Y,Z coordinates. The first step is to check if the point number is equal to the previous value in column 1. If the point number is the same, then i want to calculate the difference for the X,Y,Z coordinate. How do I do that? I have tried to use a loop, but it doesn't work after my intentions.

Original data:

A=[1 576872.757 6228394.988 3.461;

1 576872.762 6226395.008 3.460;

1 576872.766 6228394.982 3.453;

2 576851.856 6228358.766 3.844;

2 576851.872 6228358.756 3.820…….]

I want the output to look like this:

A=[ 1 0.010 0.027 0.010; %Difference between each coordinate and mean value for each point

1 0.025 0.010 0.035;

1 0.022 0.019 0.049;

2 0.010 0.027 0.038………….]

Answer 1

T = array2table(A);
m = varfun(@mean,T,'GroupingVariables',1);
out = A;
out(:,2:end) = out(:,2:end) - m{A(:,1),3:end};