How can I find maximum value within each columns and and return the entire elements in that column

Hello,

Here it is my question:

I have follwoing 3*8 matrix:

A =

0.0596 0.0714 0.8181 0.1499 0.9730 0.4538 0.0835 0.3909

0.6820 0.5216 0.8175 0.6596 0.6490 0.4324 0.1332 0.8314

0.0424 0.0967 0.7224 0.5186 0.8003 0.8253 0.1734 0.8034

What I want is finding maximum value of each two consecutive column and returning entire element of that column which includes maximum value. I also must mention that I want to compare two consecutive together and not to rest of columns. For example, I wont compare second column with third one.

Considering my description ad question following matrix B (3*4) would be the answer.

B =

0.0596 0.8181 0.9730 0.3909

0.6820 0.8175 0.6490 0.8314

0.0424 0.7224 0.8003 0.8034

Thank you so much in advance!

Answer 1

[Hernia Baby]

This code seperates A to odd and even elements, and culculates B with logical indexing.

A = [ 0.0596    0.0714    0.8181    0.1499    0.9730    0.4538    0.0835    0.3909;
    0.6820    0.5216    0.8175    0.6596    0.6490    0.4324    0.1332    0.8314;
    0.0424    0.0967    0.7224    0.5186    0.8003    0.8253    0.1734    0.8034];

A_odd = A(:,1:2:end-1);
A_even =A(:,2:2:end);
B = A_odd .* (A_odd > A_even) +A_even .* (A_even > A_odd)

B =

0.0714 0.8181 0.9730 0.3909

0.6820 0.8175 0.6490 0.8314

0.0967 0.7224 0.8253 0.8034

[Milad Naderloo]

Thank you for your answer. but my problem is finding maximum in each column and returning all elemnts of that column. It would be great if you can help with that

[Hernia Baby]

Thank you for the reply!

Then, how about the dimension option with max function?

A = [ 0.0596    0.0714    0.8181    0.1499    0.9730    0.4538    0.0835    0.3909;
    0.6820    0.5216    0.8175    0.6596    0.6490    0.4324    0.1332    0.8314;
    0.0424    0.0967    0.7224    0.5186    0.8003    0.8253    0.1734    0.8034];

B = max(A,[],1)

B =

0.6820 0.5216 0.8181 0.6596 0.9730 0.8253 0.1734 0.8314

-------------------------------------------

Detail:

https://jp.mathworks.com/help/matlab/ref/max.html?lang=en

[Hernia Baby]

And I've cached what you want to do actually.

I'm truely sorry for puzzling you...

A = [ 0.0596    0.0714    0.8181    0.1499    0.9730    0.4538    0.0835    0.3909;
    0.6820    0.5216    0.8175    0.6596    0.6490    0.4324    0.1332    0.8314;
    0.0424    0.0967    0.7224    0.5186    0.8003    0.8253    0.1734    0.8034];

A_odd = A(:,1:2:end-1);
A_even =A(:,2:2:end);

L1 = repmat(max(A_odd,[],1) > max(A_even,[],1),size(A_odd(:,1)));
L2 = repmat(max(A_odd,[],1) <= max(A_even,[],1),size(A_even(:,1)));

B = A_odd.*L1 + A_even.*L2

B =

0.0596 0.8181 0.9730 0.3909

0.6820 0.8175 0.6490 0.8314

0.0424 0.7224 0.8003 0.8034

[Milad Naderloo]

Thanks again Hernia!

The max function is ok, however, I want to have all other elemnts of the column which includs max value, and not just single value of max.

[Hernia Baby]

Thank you again! Is it okey with my last answer? If you want to do more, please let me know anything!

[Milad Naderloo]

Thank you so much, it is working really good and indeed efficient! :)