if statement for range of array values

Is there a better way to write this 'if' statement?

for i = 1:size(somevalue)

if (x(i) < xmax && x(i-1) < xmax && x(i-2) < xmax) || (y(i) < ymax && y(i-1) < ymax)

disp('do something');

end

Thanks for your help!

[Oleg Komarov]

Trivial question, do you want the condition to be verified on any (&&) of the 3 consecutive values or on all (&)?

Answer 1

[Wayne King]

How about

   if (any(x<xmax) || any(y<ymax))
    disp('do something');
   end

or do you really want to test if every one is? Of course it seems that x<xmax or y<ymax are to be always true.

[Sean de Wolski]

golf:

if any([x<k,y<p]);disp('do something');end

[Sean de Wolski]

(assuming x,y are both row vectors)

[Jan]

@Sean: This needs to create a temporary array of the length numel(x)+numel(y). Therefore I assume this is slower than Wayne's approach.

[Richard Brown]

Hence golf :)

Answer 2

[Dr. Seis]

I think what you might be after is something like:

if all(x(i-1:i+1) < xmax) || all(y(i-1:i+1) < ymax)
   % something
end

[Dr. Seis]

Misinterpreted your "if" statement on my previous attempt. This should be what you are after.

Note: "all" will return TRUE if and only if the entire array returned from "x<xmax" is all 1's. "any" will return TRUE if there is one or more 1 in the array returned by "x<xmax".

[Richard Brown]

If doing it this way, the x indices should be i-2:i, and the y indices should be i-1:i, and the loop should start at 3

Answer 3

[Richard Brown]

To check I've understood correctly, you only want to do something if the current and two preceding x values are all less than xmax, or, the current and preceding y values are both less than ymax. Then, the indices you are interested in are given by:

idx = find(filter([1 1 1], 1, x < xmax) == 3 | filter([1 1], 1, y < ymax) == 2)

Note that 1 and 2 will never appear in idx as your expression cannot be evaluated for these