# How can I discretize data by their sign?

2 views (last 30 days)
Manling Yang on 20 Sep 2022
Commented: Manling Yang on 20 Sep 2022
I would like to discretize data by their sign and return the index of 'alternating sign'.
For example if I have a vector:
A = [-2,-1,5,-10,7,3,-9,-12,11];
Their signs are like:
s = sign(A)
[-1,-1,1,-1,1,1,-1,-1,1]
I would like to return:
[1,1,2,3,4,4,5,5,6]

Stephen23 on 20 Sep 2022
A = [-2,-1,5,-10,7,3,-9,-12,11];
B = sign(A);
C = cumsum(logical([1,diff(B)]))
C = 1×9
1 1 2 3 4 4 5 5 6

### More Answers (1)

Chunru on 20 Sep 2022
A = [-2,-1,5,-10,7,3,-9,-12,11];
s = sign(A)
s = 1×9
-1 -1 1 -1 1 1 -1 -1 1
s1 = [1 diff(s)~=0]
s1 = 1×9
1 0 1 1 1 0 1 0 1
y = cumsum(s1)
y = 1×9
1 1 2 3 4 4 5 5 6
% [1,1,2,3,4,4,5,5,6]
##### 1 CommentShowHide None
Manling Yang on 20 Sep 2022
Thanks! This is really subtle!

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