mergecats
Merge categories in categorical array
Description
B = mergecats(
merges
two or more categories of a categorical array into one category. By default,
A
,oldcats
)mergecats
merges all the categories listed in
oldcats
into a new category with the same name as
oldcats(1)
. If an element of A
belongs to
a category listed in oldcats
, then the corresponding element of
B
belongs to oldcats(1)
.
Examples
Merge Categories into One Category
Create a categorical array that has categories for various colors.
A = categorical(["pink" "blue" "pink" "red" "blue" "red"])
A = 1x6 categorical
pink blue pink red blue red
Display the categories of A
. The three categories are in alphabetical order.
categories(A)
ans = 3x1 cell
{'blue'}
{'pink'}
{'red' }
Merge the categories red
and pink
into the category red
. Specify red
first in oldcats
to use it as the merged category. mergecats
replaces the value pink
with red
.
oldcats = ["red" "pink"]; B = mergecats(A,oldcats)
B = 1x6 categorical
red blue red red blue red
Display the categories of B
. The new array has fewer categories.
categories(B)
ans = 2x1 cell
{'blue'}
{'red' }
Merge Categories Out of Order
Create a categorical array that has categories for various items of clothing.
A = categorical(["shirt" "pants" "shoes" "shirt" "dress" "belt"])
A = 1x6 categorical
shirt pants shoes shirt dress belt
Display the categories of A
. If you do not specify an order, then the categories are in alphabetical order.
categories(A)
ans = 5x1 cell
{'belt' }
{'dress'}
{'pants'}
{'shirt'}
{'shoes'}
Merge the categories belt
and shoes
into a new category called other
. The value other
replaces all instances of belt
and shoes
.
B = mergecats(A,["belt" "shoes"],"other")
B = 1x6 categorical
shirt pants other shirt dress other
Display the categories of B
. The new array has four categories and the order is no longer alphabetical. other
appears in place of belt
because it is the first category that it replaces.
categories(B)
ans = 4x1 cell
{'other'}
{'dress'}
{'pants'}
{'shirt'}
Merge Categories of Ordinal Categorical Array
Create an ordinal categorical array.
A = categorical([1 2 3 2 1],1:3,["poor" "fair" "good"],Ordinal=true)
A = 1x5 categorical
poor fair good fair poor
Display the categories of A
. The categories have the mathematical ordering poor < fair < good
.
categories(A)
ans = 3x1 cell
{'poor'}
{'fair'}
{'good'}
Merge all fair
or poor
values into a new category called bad
. Because A
is ordinal, the categories to be merged must be consecutive. If they are not consecutive, then mergecats
cannot create a new set of categories that have a mathematical ordering.
B = mergecats(A,["fair" "poor"],"bad")
B = 1x5 categorical
bad bad good bad bad
Display the categories of B
. The new array has two categories with the mathematical ordering: bad < good
.
categories(B)
ans = 2x1 cell
{'bad' }
{'good'}
Specify Categories by Using Pattern
Create a categorical array. This array has many different categories that can stand for "yes" and "no".
C = categorical(["Y" "Yes" "Yeah" "N" "No" "Nope"])
C = 1x6 categorical
Y Yes Yeah N No Nope
categories(C)
ans = 6x1 cell
{'N' }
{'No' }
{'Nope'}
{'Y' }
{'Yeah'}
{'Yes' }
You can match multiple category names by using a pattern
. For example, to specify category names that start with a Y
, you can use a wildcard pattern. To create a wildcard pattern, use the wildcardPattern
function.
Merge all categories whose names start with Y
into one category named yes
. Then merge all the categories whose names start with N
into one category named no
. As a result, values that have the same meaning are all in the same category. Now, C
has only two categories.
C = mergecats(C,"Y" + wildcardPattern,"yes"); C = mergecats(C,"N" + wildcardPattern,"no")
C = 1x6 categorical
yes yes yes no no no
categories(C)
ans = 2x1 cell
{'no' }
{'yes'}
Input Arguments
A
— Input array
categorical array
Input array, specified as a categorical array.
oldcats
— Categories to merge
string array | cell array of character vectors | pattern
scalar
Categories to merge, specified as a string array, cell array of character vectors, or pattern
scalar.
If
A
is ordinal, thenoldcats
must specify a subset of categories that are consecutive. If they are not consecutive, thenmergecats
cannot create a new set of categories that has a mathematical ordering.If
A
is nonordinal, thenoldcats
can specify any subset of categories.
newcat
— New category
string scalar | character vector
New category, specified as a string scalar or a character vector.
Extended Capabilities
Tall Arrays
Calculate with arrays that have more rows than fit in memory.
The
mergecats
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
oldcats
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
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