Clear Filters
Clear Filters

How to get DBSCAN to assign the items to the clusters found

3 views (last 30 days)
I have used DBSCAN on MATLAB R2021 to cluster my data into 3 groups. I want to be able to get DBSCAN to actually assign and name the clusters based on the items. I am not sure how this is done. Can anyone help please?
Thank You
Walter Roberson
Walter Roberson on 15 Jul 2021
Do not use == to compare character vectors. You can use == to compare string() objects, or to compare a string object and a character vector, but using == to compare character vectors only works if the two are compatible sizes (taking into account implicit expansion)
Character vectors are vectors -- for example 'abc' is the vector ['a', 'b', 'c'] . And when you compare vectors they need to be the same (or compatible) size. You should think of character vectors as being collections of character codes with an internal flag set that says to represent them specially on output. 'A1' is char([65 49]) and should be treated as if it is [65 49] (numeric) rather than being a phrase.
String objects on the other hand, treat entries as collections. ["abc", "hello"] is a 1 x 2 string object that internally is fairly similar to {'abc', 'hello'} in representation, but with added useful behaviour . String objects know that == means to compare the strings rather than the character codes.
To compare character vectors use strcmp() or strcmpi() or isequal() or (in some useful ways) ismember()
NCA on 19 Jul 2021
Thanks a lot for the detailed response,it was really helpful although they only seem to compare two objects while I have many signals within the file to compare to help dbscan algorithm to assign them into the clusters found.

Sign in to comment.

Accepted Answer

Aditya Patil
Aditya Patil on 15 Jul 2021
As per my understanding, you have some data that you use for clustering, and some other corresponding data that you want to match to this data. For doing this, you rely on the data.Header.Filename attribute.
The likely issue here is that you need to use strcmp instead of “==”. Another issue might be that Filename has different values than you expect. For example, there might be case difference.

More Answers (0)


Find more on Statistics and Machine Learning Toolbox 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!