Sorting a large 3 column data set

I have a large 3 column matrix of xyz elevation data in 1 meter intervals. The data corresponds to a 100 meter by 100 meter grid, and lists the data row by row, meaning that the y term changes by 1 every 100 values. The data begins in the top right corner of the 'grid', as shown:

x y z

0 100 34

1 100 35

2 100 23

...

0 99 54

1 99 45

2 99 37

...

etc.

My problem is that the x and y values start at arbitrarily assigned values, like 499983.5, which make the data hard to work with. How can I make a new matrix with the x and y redefined from 1 to 100? This still needs to account for the fact the dataset starts in the top right corner.

Answer 1

[David Hill]

If I understand you correctly, can you not just subtract off a constant from both x and y coordinates to reset them to where you want them?

M(:,1)=M(:,1)-min(M(:,1))+1;
M(:,2)=M(:,2)-min(M(:,2))+1;