# Find places before or after zeros in vector

5 views (last 30 days)
Christian S. on 26 Aug 2021
Commented: Christian S. on 27 Aug 2021
Hi MATLAB-Community,
I'm searching for an elegant way to mark the places before and after zeros in a Vector.
e.g.:
a = 0 0 0 1 1 1 0 0 1 1 1 0 1 1 1 0 1 1 0
before = 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0
after = 0 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 1 0
Has anybody an Idea that can help me with that Problem?
Cheers
Christian

Ive J on 26 Aug 2021
Edited: Ive J on 26 Aug 2021
a = [0 0 0 1 1 1 0 0 1 1 1 0 1 1 1 0 1 1 0];
before = [0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0];
after = [0 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 1 0];
da = [diff(a), 0];
bcheck = circshift(da > 0, 1);
acheck = da < 0;
all(bcheck == before)
ans = logical
1
all(acheck == after)
ans = logical
1
This may not cover leading and trailing zeros, though before and after zeros may not make sense in that case.
Christian S. on 27 Aug 2021
Perfect, thank you very much!

R2020b

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