Creating a submatrix from a matrix

I have a matrix for example; A = {1 3 7; 10 1 2; 11 5 9; 12 2 5] (however, mine is much bigger) And I would like to keep the rows where all the elements in the row are less than or equal to 7 to put into a new submatrix called B. How would I go about this?

Many thanks for any help you can give :)

Answer 1

[José-Luis]

A = [1 3 7; 10 1 2; 11 5 9; 12 2 5]
your_mat = A(all(A<=7,2),:);

I looked at your question history. Please accept an answer if it helped you. It is the only "payment" contributors in this forum receive.

[Bran]

Hi there,

I'm so sorry Jose... I didn't realise that that is what I should do! Please accept my sincerest apologies! Many thanks for flagging this up to me! Serves my right for not reading the rules!

Happy New year! :) Bran

[José-Luis]

No worries, and no apologies needed. It's not really a rule, but something nice to do for the contributors. Anyway...

Cheers!

[Bran]

Hi there,

Just a quick question. I have applied this code to another matrix modifying it slightly to read;

your_mat = B2(all((-8/3)<=B2<=(8/3),2),:)because I want to keep all rows where the all the column numbers are greater than -8/3 or less than 8/3 however, the matrix I get is the exact same size as the original B2 and I know that this is not the case. Any ideas what could be going wrong??

Many thanks in advance :) Bran

[José-Luis]

 (-8/3)<=B2<=(8/3)

is not valid Matlab syntax. You could try instead:

 abs(B2) <= 8/3

[Bran]

Many thanks, that worked for me :)

Answer 2

[Thomas]

A = [1 3 7; 10 1 2; 11 5 9; 12 2 5]
out=A(find(sum(A<=7,2)==size(A,2)),:)   % rows with elements <=7

[Bran]

Thanks Guys for all the help!

Answer 3

[Azzi Abdelmalek]

A = {1 3 7; 10 1 2; 11 5 9; 12 2 5};
B=cell2mat(A);
out1=B(B<7);
n=numel(out1);
n1=floor(sqrt(n));
m1=ceil(n/n1);
out=cell(1,n1*m1);
out(1:n)=num2cell(out1)';
B=reshape(out,n1,m1)

[Bran]

Many thanks for the help!

Answer 4

[nabin]

I have a matrix A=[1 2 3; 1 2 9; 2 3 4]. I want a matrix B whose column 1 is equal to 1. How can I do this? B=[1 2 3; 1 2 9]