Index an array using specific indices
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I have a vector
x = [0,1,1,0,1,...,N] % x is vector containing either 1s or 0s of size N = 107199.
then I have another vector s, which contains index locations in x.
s= [23,100,500, 9888,....N] % s is of size 1x518
so I want to filter s to contain only indices where the values in x are 1s.
I tried something like this,
idx = x(s)~=1;
new_s = s(idx);
but it gives me this error Index exceeds the number of array elements (107520).. any idea what im doing wrongly?
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Réponses (4)
Daniel Neubauer
le 4 Nov 2022
x=[1 0 1 1 0 0 0 0 1 0];
s=[9 4 6];
snew=s(x(s)==1)
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KALYAN ACHARJYA
le 4 Nov 2022
Modifié(e) : KALYAN ACHARJYA
le 4 Nov 2022
Yes, I noticed the array length later.
DGM
le 4 Nov 2022
Try
% some test vectors
x = randi([0 1],1,20)
s = randi([1 numel(x)],1,10)
% this is the content selected by s
x(s)
% and then this would be cases where s selects 1s within x
new_s = s(x(s)==1)
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dpb
le 4 Nov 2022
Well, if size N = 107199 while s is of size 1x518, then 107199 > 518 so any location in x past numel(s) is going to be an out of bounds reference.
It's not clear in isolation what relationship there is (if any) between x and s so why one would expect those two to be commensurate is puzzling.
Perhaps you're looking for locations that are in s that were found in some other fashion and wanting to know if there's a corresponding matching "1" value in x at the specific location? That's about the only way I can think of at the moment to relate the two -- if that were the case then try
new_s=s(ismember(s,find(~x)));
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