union

(Not Recommended) Set union for dataset array observations

The dataset data type is not recommended. To work with heterogeneous data, use the MATLAB^® table data type instead. See MATLAB table documentation for more information.

Syntax

C = union(A,B)

C = union(A,B,vars)

C = union(A,B,vars,setOrder)

[C,iA,iB] = union(___)

Description

C = union(A,B) for dataset arrays A and B returns the combined set of observations from the two arrays, with repetitions removed. The observations in the dataset array C are sorted.

C = union(A,B,vars) returns the combined set of observations from the two arrays, with repetitions of unique combinations of the variables specified in vars removed. The observations in the dataset array C are sorted by those variables.

The values for variables not specified in vars for each observation in C are taken from the corresponding observation in A or B, or from A if there are common observations in both A and B. If there are multiple observations in A or B that correspond to an observation in C, those values are taken from the first occurrence.

C = union(A,B,vars,setOrder) returns the observations in C in the order specified by setOrder.

[C,iA,iB] = union(___) also returns index vectors iA and iB such that C is a sorted combination of the values A(iA,:) and B(iB,:). If there are common observations in A and B, then union returns only the index from A, in iA. If there are repeated observations in A or B, then the index of the first occurrence is returned. You can use any of the previous input arguments.

Input Arguments

A,B — Input arrays

dataset objects

Input arrays, specified as dataset objects.

vars — Variable names

string array | cell array of character vectors | vector of integers containing variable column numbers

Variable names, specified as a string array, cell array of character vectors, or vector of integers containing variable column numbers. vars indicates the variables in A and B that union considers.

Specify vars as [] to use its default value of all variables.

setOrder — Flag indicating sorting order for observations in the resulting array

'sorted' (default) | 'stable'

Flag indicating sorting order for observations in the resulting array C, specified as 'sorted' or 'stable'.

'sorted'	Observations in C are in sorted order (default).
'stable'	Observations in C are in the same order that they appear in A, then B.

Output Arguments

C — Dataset array with the combined observations of A and B

dataset object

Dataset array with the combined observations of A and B, with repetitions removed, returned as a dataset object. C is in sorted order (by default), or the order specified by setOrder.

iA — Index vector indicating observations in A that contribute to the union

vector of integers

Index vector indicating observations in A that contribute to the union, returned as a vector of integers. The vector iA contains the index to the first occurrence of any repeated observations in A.

iB — Index vector indicating observations in B that contribute to the union

vector of integers

Index vector indicating observations in B that contribute to the union, returned as a vector of integers. The vector iB contains the index to the first occurrence of any repeated observations in B.

Version History

Introduced in R2012b