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.

Answer 1

[Gurudatha Pai]

A = 4;
Z = [1 9 2 3 4 5]
Z1 = Z(find(Z~=A))

that should work

Answer 2

[Walter Roberson]

Z(Z==A) = [];

Warning: if you have floating point numbers instead of integers, you will usually need to compare with a tolerance instead of ==

Answer 3

[Tiasa Ghosh]

You can also use setdiff function.

a=4;
z=[1 9 2 3 4 5];
setdiff(z,a)

[Gospel Oh]

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

[Paul Smits]

@Gospel Oh

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')

Answer 4

[Richard Barrett-Jolley]

Yes, that would work, but I would recommend simply:

    Z=Z(Z~=A);

[Walter Roberson]

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.

[Walter Roberson]

My testing suggests that Z=Z(Z~=A) is faster than deleting from Z, taking about 82% as long, at least for longer arrays.

[huda nawaf]

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

[Walter Roberson]

Z = Z(~ismember(Z, A));