How to count "gaps" consisting of designated values in a vector?
34 views (last 30 days)
Show older comments
I have a very long vector of data that includes gaps of "invalid" values where data that's missing has been replaced with a designated missing data value (e.g. -1) or with "NaN".
invalid_values = [-1 NaN];
sample_data_vector = [22 23 22 24 -1 -1 -1 25 20 24 NaN Nan NaN 25 24 -1 -1 22 20 NaN 23];
I want to summarize info on the length of the gaps of invalid data (and no need to distinguish between whether the value is Nan or -1 or some other number). It might be helpful to know that my goal is to compare gap lengths over subsequent trials to determine whether gaps are getting longer/shorter and more/less frequent.
So for the above sample vector I'd get a matrix output that summarizes the following info about the gaps:
Length: 1 Number of occurences: 1
Length: 2 Number of occurences: 1
Length: 3 Number of occurences: 2
How would I write code to do this?
0 Comments
Accepted Answer
Matt J
on 18 Dec 2018
Edited: Matt J
on 18 Dec 2018
One way, assuming you have the Image Processing Toolbox,
bw=ismember(sample_data_vector, invalid_values)|isnan(sample_data_vector);
S=regionprops(bw,'Area');
gaplengths=[S.Area];
H = histcounts(gaplengths,1:max(gaplengths)+1) %output histogram
5 Comments
Matt J
on 8 Jun 2021
That will just be,
gap.start_indices = find( diff([0,bw])>0 );
gap.end_indices = find( diff([bw,0])<0 );
gap.length = gap.end_indices-gap.start_indices+1;
More Answers (0)
See Also
Categories
Find more on Logical in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!