Ordinal Categorical Arrays
In this section...
“Order of Categories” on page 8-36
“How to Create Ordinal Categorical Arrays” on page 8-36
“Working with Ordinal Categorical Arrays” on page 8-38
Order of Categories
categorical is a data type to store data with values from a finite set of discrete categories, which
can have a natural order. You can specify and rearrange the order of categories in all categorical
arrays. However, you only can treat ordinal categorical arrays as having a mathematical ordering to
their categories. Use an ordinal categorical array if you want to use the functions min, max, or
relational operations, such as greater than and less than.
The discrete set of pet categories {'dog' 'cat' 'bird'} has no meaningful mathematical
ordering. You are free to use any category order and the meaning of the associated data does not
change. For example, pets = categorical({'bird','cat','dog','dog','cat'}) creates a
categorical array and the categories are listed in alphabetical order, {'bird' 'cat' 'dog'}. You
can choose to specify or change the order of the categories to {'dog' 'cat' 'bird'} and the
meaning of the data does not change.
ordinal categorical arrays contain categories that have a meaningful mathematical ordering. For
example, the discrete set of size categories {'small', 'medium', 'large'} has the
mathematical ordering small < medium < large. The first category listed is the smallest and the
last category is the largest. The order of the categories in an ordinal categorical array affects the
result from relational comparisons of ordinal categorical arrays.
How to Create Ordinal Categorical Arrays
This example shows how to create an ordinal categorical array using the categorical function with
the 'Ordinal',true name-value pair argument.
Ordinal Categorical Array from a Cell Array of Character Vectors
Create an ordinal categorical array, sizes, from a cell array of character vectors, A. Use valueset,
specified as a vector of unique values, to define the categories for sizes.
A = {'medium' 'large';'small' 'medium'; 'large' 'small'};
valueset = {'small', 'medium', 'large'};
sizes = categorical(A,valueset,'Ordinal',true)
sizes = 3x2 categorical
medium
large
small
medium
large
small
sizes is 3-by-2 ordinal categorical array with three categories such that small < medium <
large. The order of the values in valueset becomes the order of the categories of sizes.
8 Categorical Arrays
8-36
In this section...
“Order of Categories” on page 8-36
“How to Create Ordinal Categorical Arrays” on page 8-36
“Working with Ordinal Categorical Arrays” on page 8-38
Order of Categories
categorical is a data type to store data with values from a finite set of discrete categories, which
can have a natural order. You can specify and rearrange the order of categories in all categorical
arrays. However, you only can treat ordinal categorical arrays as having a mathematical ordering to
their categories. Use an ordinal categorical array if you want to use the functions min, max, or
relational operations, such as greater than and less than.
The discrete set of pet categories {'dog' 'cat' 'bird'} has no meaningful mathematical
ordering. You are free to use any category order and the meaning of the associated data does not
change. For example, pets = categorical({'bird','cat','dog','dog','cat'}) creates a
categorical array and the categories are listed in alphabetical order, {'bird' 'cat' 'dog'}. You
can choose to specify or change the order of the categories to {'dog' 'cat' 'bird'} and the
meaning of the data does not change.
ordinal categorical arrays contain categories that have a meaningful mathematical ordering. For
example, the discrete set of size categories {'small', 'medium', 'large'} has the
mathematical ordering small < medium < large. The first category listed is the smallest and the
last category is the largest. The order of the categories in an ordinal categorical array affects the
result from relational comparisons of ordinal categorical arrays.
How to Create Ordinal Categorical Arrays
This example shows how to create an ordinal categorical array using the categorical function with
the 'Ordinal',true name-value pair argument.
Ordinal Categorical Array from a Cell Array of Character Vectors
Create an ordinal categorical array, sizes, from a cell array of character vectors, A. Use valueset,
specified as a vector of unique values, to define the categories for sizes.
A = {'medium' 'large';'small' 'medium'; 'large' 'small'};
valueset = {'small', 'medium', 'large'};
sizes = categorical(A,valueset,'Ordinal',true)
sizes = 3x2 categorical
medium
large
small
medium
large
small
sizes is 3-by-2 ordinal categorical array with three categories such that small < medium <
large. The order of the values in valueset becomes the order of the categories of sizes.
8 Categorical Arrays
8-36