iscategory

Determine if inputs are names of categories

Syntax

tf = iscategory(A,catnames)

Description

tf = iscategory(A,catnames) returns an array containing logical 1 (true) where the data in catnames is a category of A. Otherwise, iscategory returns logical 0 (false).

tf is the same size as catnames.

Examples

Determine If Names Are Categories

Create a categorical array.

A = categorical(["shirt" "pants"; "pants" "hat"; "shirt" "pants"])

A = 3×2 categorical
     shirt      pants 
     pants      hat   
     shirt      pants 

The categories of A are names of articles of clothing. They come from the unique values of the input array.

categories(A)

ans = 3×1 cell
    {'hat'  }
    {'pants'}
    {'shirt'}

Determine if the names of articles of clothing, shirt, pants, socks, and shoes, are categories of A.

catnames = ["shirt" "pants" "socks" "shoes"]

catnames = 1×4 string
    "shirt"    "pants"    "socks"    "shoes"

tf = iscategory(A,catnames)

tf = 1×4 logical array

   1   1   0   0

shirt and pants are categories of A, but socks and shoes are not.

iscategory does not tell us anything about the category, hat, because it was not included in catnames.

Test for Category with No Corresponding Data

Create a categorical array.

data = ["plane" "car" "train" "car" "plane"];
categoriesOfData = ["boat" "car" "plane" "train"];
A = categorical(data,categoriesOfData)

A = 1×5 categorical
     plane      car      train      car      plane 

categories(A)

ans = 4×1 cell
    {'boat' }
    {'car'  }
    {'plane'}
    {'train'}

Determine if boat is a category in A.

tf = iscategory(A,"boat")

tf = logical
   1

iscategory returns 1 (true), even though no element of A belongs to the category boat.

Match Names of Categories by Using Pattern

Create a categorical array.

C = categorical(["Y" "Yes" "Yeah" "N" "No" "Nope"])

C = 1×6 categorical
     Y      Yes      Yeah      N      No      Nope 

You can match one or more category names by using a pattern. For example, determine if any category names start with a Y by using a wildcard pattern. You can create a wildcard pattern with the wildcardPattern function.

tf = iscategory(C,"Y" + wildcardPattern)

tf = logical
   1

Determine if any category names start with an X.

tf = iscategory(C,"X" + wildcardPattern)

tf = logical
   0

Input Arguments

A — Input array

categorical array

Input array, specified as a categorical array.

catnames — Category names

string array | character vector | cell array of character vectors | pattern array

Category names, specified as a string array, character vector, cell array of character vectors, or pattern array.

Extended Capabilities

Tall Arrays

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

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

C/C++ Code Generation

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

Usage notes and limitations:

• The catnames input argument does not support pattern expressions.

For more information, see Code Generation for Categorical Arrays (MATLAB Coder).

Thread-Based Environment

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

This 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™.

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

Version History

Introduced in R2013b