Grouping and averaging values within a matrix

Hello, I have a matrix 305109x3 and I want to reduce its size by averaging similar values within the matrix.

The matrix data varies from -1.6 to 1.3 on column one and I want to for example take all the values close to -1.6 on column one and average them.

This is a section of my matrix, column 1 2 3 correspond to x y z data points:

-1.60120522975922 -0.522726416587830 1.67500007152557

-1.60120522975922 -0.518805325031281 1.67500007152557

-1.59728419780731 -0.522726416587830 1.67500007152557

-1.59650182723999 -0.551117777824402 1.66600012779236

-1.59650182723999 -0.547217786312103 1.66600012779236

-1.59650182723999 -0.543317794799805 1.66600012779236

-1.59650182723999 -0.539417743682861 1.66600012779236

-1.59650182723999 -0.535517752170563 1.66600012779236

-1.59650182723999 -0.508217751979828 1.66600012779236

-1.59650182723999 -0.504317700862885 1.66600012779236

-1.59642553329468 -0.564169049263001 1.67000007629395

-1.59642553329468 -0.560259699821472 1.67000007629395

-1.59642553329468 -0.528984725475311 1.67000007629395

-1.59642553329468 -0.525075435638428 1.67000007629395

-1.59642553329468 -0.513347327709198 1.67000007629395

-1.59336316585541 -0.522726416587830 1.67500007152557

-1.59260189533234 -0.566717803478241 1.66600012779236

-1.59260189533234 -0.555017769336700 1.66600012779236

-1.59260189533234 -0.551117777824402 1.66600012779236

-1.59260189533234 -0.547217786312103 1.66600012779236

-1.59260189533234 -0.539417743682861 1.66600012779236

-1.59260189533234 -0.531617760658264 1.66600012779236

-1.59260189533234 -0.508217751979828 1.66600012779236

-1.59260189533234 -0.504317700862885 1.66600012779236

-1.59251618385315 -0.525075435638428 1.67000007629395

-1.59251618385315 -0.517256677150726 1.67000007629395

-1.59251618385315 -0.513347327709198 1.67000007629395

So in this case I would like to average all the values close to -1.6 and all the values close to -1.59.

So instead of having the above 27x3 matrix, I would have a 2x3 matrix.

For reference the 2x3 matrix I would like after doing that would be:

-1.60121 -0.52077 1.675

-1.58829 -0.5472 1.678788

So, for the whole matrix, I would have -1.6, -1.59, -1.58 all up to 1.3 and want to be able to identify numbers close to those and average them, if that make sense?

[Dyuman Joshi]

How do you define close? What is the tolerance criteria? -1.6 +- 0.1?

"So in this case I would like to average all the values close to -1.6 and all the values close to -1.59."

Do you mean 1.3, instead of -1.59?

[JIAN-HONG YE ZHU]

The tolerance criteria is 0.01. My matrix contains values from -1.6 to 1.3 but the posted matrix only goes from -1.6 to -1.59 since there are too many data points.

So I would like all row values close to -1.6 to be averaged and give my one row containing that, same with -1.59, -1.58, -1.57, -1.56 and so on.

I included the variable since I might not be explaning myself right.

Answer 1

[Kevin Holly]

m = [-1.60120522975922 -0.522726416587830 1.67500007152557
-1.60120522975922 -0.518805325031281 1.67500007152557
-1.59728419780731 -0.522726416587830 1.67500007152557
-1.59650182723999 -0.551117777824402 1.66600012779236
-1.59650182723999 -0.547217786312103 1.66600012779236
-1.59650182723999 -0.543317794799805 1.66600012779236
-1.59650182723999 -0.539417743682861 1.66600012779236
-1.59650182723999 -0.535517752170563 1.66600012779236
-1.59650182723999 -0.508217751979828 1.66600012779236
-1.59650182723999 -0.504317700862885 1.66600012779236
-1.59642553329468 -0.564169049263001 1.67000007629395
-1.59642553329468 -0.560259699821472 1.67000007629395
-1.59642553329468 -0.528984725475311 1.67000007629395
-1.59642553329468 -0.525075435638428 1.67000007629395
-1.59642553329468 -0.513347327709198 1.67000007629395
-1.59336316585541 -0.522726416587830 1.67500007152557
-1.59260189533234 -0.566717803478241 1.66600012779236
-1.59260189533234 -0.555017769336700 1.66600012779236
-1.59260189533234 -0.551117777824402 1.66600012779236
-1.59260189533234 -0.547217786312103 1.66600012779236
-1.59260189533234 -0.539417743682861 1.66600012779236
-1.59260189533234 -0.531617760658264 1.66600012779236
-1.59260189533234 -0.508217751979828 1.66600012779236
-1.59260189533234 -0.504317700862885 1.66600012779236
-1.59251618385315 -0.525075435638428 1.67000007629395
-1.59251618385315 -0.517256677150726 1.67000007629395
-1.59251618385315 -0.513347327709198 1.67000007629395];

m(:,1) = round(m(:,1),2);

m

m = 27×3

-1.6000 -0.5227 1.6750 -1.6000 -0.5188 1.6750 -1.6000 -0.5227 1.6750 -1.6000 -0.5511 1.6660 -1.6000 -0.5472 1.6660 -1.6000 -0.5433 1.6660 -1.6000 -0.5394 1.6660 -1.6000 -0.5355 1.6660 -1.6000 -0.5082 1.6660 -1.6000 -0.5043 1.6660

unique_values = unique(m(:,1))

unique_values = 2×1

-1.6000 -1.5900

for ii = 1:length(unique_values)
    logical_array = m(:,1) == unique_values(ii);
    new(ii,:) = mean(m(logical_array,:));
end
new

new = 2×3

-1.6000 -0.5323 1.6691 -1.5900 -0.5318 1.6678

[JIAN-HONG YE ZHU]

Thank you very much!