any

Determine if any element is non-zero.

Usages

b = any(A)

• When A is a scalar, b is logical 1 if A is non-zero, and logical 0 if otherwise.
• When A is a vector, b is logical 1 if at least one element of A is non-zero, and logical 0 if otherwise.
• When A is a matrix or an array of ndims(A) >= 3, an element of b is assigned logical 1 if at least one element of corresponding vector of A along the first non-singleton dimension is non-zero, and logical 0 if otherwise.
• any(A) collapses the first non-singleton dimension of A. That means, if size(A) is [s1, s2, ..., sN], then size(b) is equal to [1, s2, s3, ..., sN].

b = any(A, k)

• k should be a real positive integer scalar.
• An element of b is assigned logical 1 if any element of the corresponding vector of A along the k-th dimension is non-zero, and logical 0 if otherwise.

Discussions

• A complex number is zero if both real and imaginary parts are zero.
• It ignores any NaN present in A. This is equivalent to replacing all NaN values in A by 0. As a result, any(NaN) gives 0.
• If A is a character array, it is first converted to a double array.
• Calling any(A) and any(A, k) always return an empty array when A is empty.

Example

• Check if vectors along the 3rd dimension of a random matrix a has any non-zero elements.

Input

a=randi(4,3,3,3) - 2
any(a,3)

Output

a(:, :, 1) =

-1.000   0.000  -1.000
 2.000   2.000   0.000
 0.000  -1.000  -1.000

a(:, :, 2) =

 1.000   0.000  -1.000
 1.000   2.000   1.000
 0.000   1.000   2.000

a(:, :, 3) =

 0.000   0.000   1.000
-1.000   1.000   1.000
 1.000   0.000   2.000

ans =
 1   0   1
 1   1   1
 1   1   1

• When k > ndims(A), calling any(A, k) is the same as performing any() to each of the elements of A.

Input

r=rand(2, 3, 4);
% Creating the array rr with some zeros.
rr = r.*(r>0.5)
any(rr, 4)

Output

rr(:, :, 1) = 1e-1 ×
 5.9314   8.6059   0.0000
 5.3948   0.0000   0.0000

rr(:, :, 2) = 1e-1 ×
 8.5716   7.0417   5.3465
 0.0000   0.0000   8.6345

rr(:, :, 3) = 1e-1 ×
 6.9417   9.0411   8.1402
 0.0000   0.0000   0.0000

rr(:, :, 4) = 1e-1 ×
 5.2895   6.0550   6.0822
 0.0000   7.0642   5.7643

ans(:, :, 1) = 
1  1  0
1  0  0

ans(:, :, 2) = 
1  1  1
0  0  1

ans(:, :, 3) = 
1  1  1
0  0  0

ans(:, :, 4) = 
1  1  1
0  1  1