Create a matrix on the basis of other matrix

2 views (last 30 days)
Hi given a vector
SPI= [2 3 4 8 11 13 14 15 16 19 20];
and the array
AA= [1 2 3 4 0 11 15;
0 0 0 8 13 16 0;
0 0 0 0 0 18 0;
0 0 0 0 0 19 0;
0 0 0 0 0 20 0];
I want to create a matrix DD that is AA but with just the element inside SPI. So:
DD = [ 2 3 4 0 11 15;
0 0 8 13 16 0;
0 0 0 0 0 0;
0 0 0 0 19 0;
0 0 0 0 20 0];
may someone help me?
  2 Comments
Walter Roberson
Walter Roberson on 14 Oct 2019
I notice that you delete the first column of AA as it is left without any elements from SPI. Why are you not also deleting the all-zero row 3 ? Or if the rule is that the first row has to contain an element from SPI, why are you not deleting the column [0; 13; 0; 0; 0] ? What are the rules?
luca
luca on 14 Oct 2019
Edited: luca on 14 Oct 2019
the array SPI could vary and contain all the elements of AA, that instead is fixed. So depending on the value inside SPI I want to derive DD.
Sorry for the third column, was my mistake! now it's fixed

Sign in to comment.

Accepted Answer

Fabio Freschi
Fabio Freschi on 14 Oct 2019
Edited: Fabio Freschi on 14 Oct 2019
% your data
SPI = [2 3 4 8 11 13 14 15 16 18 19 20];
AA = [1 2 3 4 0 11 14 15;
0 0 0 8 13 16 0 0;
0 0 0 0 0 0 0 0;
0 0 0 0 0 19 0 0;
0 0 0 0 0 20 0 0];
% mask
iMask = ismember(AA,SPI);
% matrix DD with zeros
DD = AA.*iMask;
% now you can filter out the rows and cols of all zeros
DD = DD(:,any(iMask,1)); % cols filter
DD = DD(any(iMask,2),:); % rows filter
  6 Comments
Walter Roberson
Walter Roberson on 15 Oct 2019
Fabio's suggested code will eliminate the row 0 0 0 0 0 0;
I do not understand at the moment why that row is being kept in the desired solution.
Fabio Freschi
Fabio Freschi on 15 Oct 2019
Me neither! but I kept all steps separated to that the OP can pick the parts of his choice

Sign in to comment.

More Answers (0)

Categories

Find more on Resizing and Reshaping Matrices in Help Center and File Exchange

Tags

Products


Release

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!