Finding a minumum range of sequential values
2 views (last 30 days)
Show older comments
Further to a question that was asked a few days ago (which Matt Fig answered to the satisfaction of the author - see link below):
http://www.mathworks.com/matlabcentral/answers/9393-basic-question-how-to-find-range-of-index-values
In particular, I am searching for a sequence of a minimum of 5 ones in order to perform another function on these elements. That is to say that I would like to perform the second function on any sequence where 5 or more ones may occur. Currently my code looks like:
S3 = findstr(B, ones(1, 5));
But when performing the second action, should the sequence happen to be greater than 5, I find that only the first 5 values identified with the code above are addressed. For example, I have a run of 10 ones, where only the first five values are are found and subsequently computed. Instead, I would like to compute values for all 10 elements appearing in the sequence.
Any ideas on how I might be able to get around this?
The data is a single row vector (1 X 14620); A range of integers where min value = 1 and max value = 6578
e.g
B = [17 4 1 3 2 3 2 1 1 1 1 1 1 1 1 1 1 2 .........12 1 15 372 3 1 1 1 2 42 93 1 105 5 1 1 1 1 78 1 2]
0 Comments
Accepted Answer
Matt Fig
on 22 Jun 2011
What else does your data look like? Is it ones and zeros? Integers only? A single row vector, or matrix? Give all the details you can...
%
%
%
%
EDIT With more details added...
x = B==1; % Sequences of 1s, change this line to find other values.
t = [1 diff(x)]~=0;
x = x(t);
t = find([t 1]);
n = diff(t);
idx = (x==1 & n>=5); % Seq. length >= 5, change this for other lengths.
n = n(idx) % Length of each sequence of 1s.
idx = t(idx) % Starting index of each sequence.
More Answers (3)
Image Analyst
on 22 Jun 2011
If you have the Image Processing Toolbox, it's trivial. Just call bwlabel and regionprops (asking for Area and PixelIdxList), find those with area >= 5, and you're done in only about 3 lines of code, with the indexes of all 1's in a run of 5 or more.
Walter Roberson
on 22 Jun 2011
By the way:
endpos = find(B(S3(1):end)~=1,1);
if endpos is empty then everything to the end of B is 1's.
0 Comments
Andrei Bobrov
on 22 Jun 2011
x = B == 1;
idx1int = [strfind([0 x],[0 1]); strfind(x,[1 0])];
idxout = idx1int(:,diff(idx1int,1)+1>=5);
nout = diff(idxout,1)+1;
0 Comments
See Also
Categories
Find more on Characters and Strings in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!