isundefined

R2026b

Find undefined elements in categorical array

Syntax

tf = isundefined(A)

Description

tf = isundefined(A) returns a logical array that indicates which elements in a categorical array are 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 categorical values are missing values, similar to NaNs, NaTs, and missing strings for other data types.

Examples

Find Undefined Elements

Create a categorical array 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 = 5×2 categorical
     <undefined>      red         
     green            blue        
     green            red         
     blue             <undefined> 
     red              red         

Array elements corresponding to the numeric value 4 in the input array do not have a corresponding category. Therefore, they are undefined in the output categorical array.

Find undefined elements in the categorical array.

tf = isundefined(A)

tf = 5×2 logical array

   1   0
   0   0
   0   0
   0   1
   0   0

Input Arguments

A — Input array

categorical array

Input array, specified as a categorical array.

Output Arguments

tf — True or false result

1 | 0 | logical array

True or false result, returned as a 1 or 0 of data type logical.

Extended Capabilities

Tall Arrays

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

The isundefined 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).

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

The isundefined function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Distributed Arrays

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

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

Version History

Introduced in R2013b