How to find out if a logical array is all zeros?

I have a logical array that is 100x1 logical. sometimes it contains a mix of numbers and sometimes it contains all 0s.

How would i go about making an if statement that checks to see if all 100x1 is 0s and if all 0s = do something

I thought i was correct in using any command but im not sure that works correctly for me..

Thanks!

Answer 1

[John D'Errico]

any does work, with a slight tweak. But you could also use all, or sum, or nnz, or even find. There are certainly many ways.

if ~any(X)
   ...
end

if all(~X)
   ...
end

if sum(x) == 0
   ...
end

if numel(find(x)) == 0
   ...
end

if nnz(x) == 0
   ...
end

Any of those tools would suffice.

Answer 2

[Turlough Hughes]

One way:

~any(x)

Answer 3

[William Rose]

@MKM,

If A is a vector,

sum(abs(A))

will be zero, or not, of all the elements are zero, or not.

If A is a 2D array, do

sum(sum(abs(A)))

Answer 4

[David Hill]

if all(~yourArray)

Answer 5

[Steven Lord]

For a vector, all with one input will work.

x = ones(10, 1);
all(x > 0) % true

ans = logical
   1

For a non-vector array you probably want to specify a dimension. In recent releases, you can specify a vector of dimensions on which to operate or you can specify 'all' as the dimension to operate on all the dimensions no matter how many there are.

x = ones(10, 10);
all(x > 0) % Only operate on dimension 1

ans = 1×10 logical array
   1   1   1   1   1   1   1   1   1   1

all(x > 0, 'all') % Operate on dimensions 1 and 2

ans = logical
   1

x = ones(10, 10, 10);
all(x > 0, [1 3]) % Operate on dimensions 1 and 3

ans = 1×10 logical array
   1   1   1   1   1   1   1   1   1   1

all(x > 0, 'all') % Operate on dimensions 1, 2, and 3

ans = logical
   1

[MKM]

This is great! Thanks for taking the time to help me with this.