Removing a specific number from vector

Hi Everyone,
Suppose I have the following
A = 4
and
Z = [1 9 2 3 4 5]
how do I remove the value A from Z, to get
Z = [1 9 2 3 5]
Regards,
Ulrik.

回答(4 个)

Z(Z==A) = [];
Warning: if you have floating point numbers instead of integers, you will usually need to compare with a tolerance instead of ==
You can also use setdiff function.
a=4;
z=[1 9 2 3 4 5];
setdiff(z,a)

2 个评论

If the function were to be put into MatLab, the answer actually comes out to be an ordered version, missig the a:
ans = 1 2 3 5 9
close, but not quite
You may pass 'stable' as additional input to setdiff, to prevent sorting:
a=4;
z=[1 9 2 3 4 5];
setdiff(z,a,'stable')

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Yes, that would work, but I would recommend simply:
Z=Z(Z~=A);

4 个评论

I don't think I've seen anyone benchmark expressing as a subset copy, compared to expressing as a deletion such as I did.
Personally I find the deletion easier to read.
My testing suggests that Z=Z(Z~=A) is faster than deleting from Z, taking about 82% as long, at least for longer arrays.
HI
Im facing the same problem, but the size of A is more than one.
so Z=Z(Z~=A); does not work. Is there an alternative?
Thanks

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