find values around a given row value

I have a 2 column matrix where I have a row of interest. i.e.

 A =

    2.5000    2.3500
    2.5600    3.3300
    2.4500    3.1000
    etc....

and I want to find say 100 rows past the row of interest (2.5 2.35) (i.e. down the matrix). Is there a function for this? thanks.

Answer 1

[Azzi Abdelmalek]

idx=find(ismember(A,[ 2.5000  2.3500],'rows'),1)
out=A(idx+1:idx+100,:)

[MacKenzie]

great, thanks! what if I have the index (since the values often repeat in my matrix) of the A position I want, then I want the next 100 values put into a new matrix? i.e. I should loop this since I have 20+ values in the matrix to find and graph the next 100 values....

for i= 1:length(TS) %TS is the indx of values I want to find in A
    idx = TS(i) 
    out(i) = A(idx:idx+100,:);
end

?

[Azzi Abdelmalek]

idx=find(ismember(A,[ 2.5000  2.3500],'rows'))
out=arrayfun(@(x) A(x+1:x+100,:),idx,'un',0)

[MacKenzie]

cool. so assuming I have the idx already (some other matrix, TS), easy way to loop this?

I tried:

for i= 1:length(TS)
    idx = TS(i);
    out=arrayfun(@(x) sFNxy(x+1:x+500,:),idx,'un',0);

end

but it works only for the first value in my matrix TS - am I missing something?

[Azzi Abdelmalek]

You are erasing the variable out each iteration. just write

out=arrayfun(@(x) sFNxy(x+1:x+500,:),TS,'un',0);

[MacKenzie]

Ah! thanks SO much!

[Walter Roberson]

QIANG SUN comments to Azzi:

great!

Answer 2

[Youssef Khmou]

you can use minimum absolute value as the following :

 % data generation
 p1=2.5;p2=2.35;
 A=ones(600,2);
 A(:,1)=A(:,1)*p1;
 A(:,2)=A(:,2)*p2;
 A=A+randn(size(A); % additive noise

 %processing
 eps=0.02;
 B(:,1)=abs(A(:,1)-p1);
 B(:,2)=abs(A(:,2)-p2);
 Result=B(B<eps);