MATLAB: How to plot specific rows and columns from a matrix

matrixplotting

I have a 50×50 matrix, however the only rows & columns I want to plot are 1:16, 18 and 50.

Ideally, this new matrix I want to print will be 18×18 with the rows/cols specified above

Is there anyway I can only return the rows and columns I care about? Thanks

Hi Ian

generating test matrix

A=randi([0 100],50);
imshow(uint8(A))

selecting

L=[1:16 18 50];
A2=A(L,L)

visually verifying selected pixels in white

A(L,L)=255 
figure(2);imshow(uint8(A))

the 18x18 result in A2

figure(3);imshow(uint8(A2))

imshow is just to ask you if the selected pixels are the ones you mean by 'rows & columns .. 1:16, 18 and 50.'

if you find this answer useful would you please be so kind to mark my answer as Accepted Answer?

To any other reader, please if you find this answer of any help solving your question,

please click on the thumbs-up vote link,

thanks in advance

John BG

the following examples may help

x = strmatch('max', char('max', 'minimax', 'maximum'))

returns

x = [1; 3] since rows 1 and 3 begin with 'max'. The statement

while

x = strmatch('max', char('max', 'minimax', 'maximum'),'exact')

returns

x = 1, since only row 1 matches 'max' exactly.

if you find these lines useful would you please mark my answer as Accepted Answer?

thanks in advance for time and attention

John BG

row=find(sum(BWImage,2)==0,1,'last')+1;
col=find(BWImage(row,:)~=0);
row=row*ones(size(col));
Points=[row(:) col(:)];

Points contains the row and column of the point or points at the top.