isundefined

Find undefined elements in categorical array

Syntax

TF = isundefined(A)

Description

TF = isundefined(A) returns a logical array, TF, that indicates which elements in the categorical array, A, contain undefined values. isundefined returns logical 1 (true) for undefined elements; otherwise it returns logical 0 (false). The size of TF is the same as the size of A.

Any elements in A without a corresponding category are undefined. Undefined values are similar to NaN in numeric arrays.

Examples

Categorical Array with Undefined Values

Create a categorical array, A, from numeric values where 1, 2, and 3 represent red, green, and blue respectively.

A = categorical([4 1; 2 3; 2 1; 3 4; 1 1],1:3,{'red','green','blue'})

A = 5x2 categorical
     <undefined>      red         
     green            blue        
     green            red         
     blue             <undefined> 
     red              red         

A is a 5-by-2 categorical array with three categories: red, green, and blue. Array elements corresponding to the numeric value 4 in the input array to the categorical function do not have a corresponding category. Therefore, they are undefined in the output categorical array, A.

Find undefined elements in A.

TF = isundefined(A)

TF = 5x2 logical array

   1   0
   0   0
   0   0
   0   1
   0   0

A(1,1) and A(4,2) are undefined.

Input Arguments

A — Categorical array

vector | matrix | multidimensional array

Categorical array, specified as a vector, matrix, or multidimensional array.

Extended Capabilities

Tall Arrays

Calculate with arrays that have more rows than fit in memory.

This function fully supports tall arrays. For more information, see Tall Arrays.

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

This function fully supports code generation. For more information, see Code Generation for Categorical Arrays (MATLAB Coder).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).