Since R2022a

## Syntax

``factorIDs = addFactor(graph,factor)``
``factorIDs = addFactor(graph,factor,groupID)``

## Description

````factorIDs = addFactor(graph,factor)` adds one or more factors, `factor`, to the specified `factorGraph` object `graph` and returns the IDs `factorIDs` of the added factors.If adding the factors results in an invalid node, then `addFactor` returns an error, and indicates the invalid nodes. Note`addFactor` supports only single-factor addition for the `factorIMU` and `factorGPS` objects. ```
````factorIDs = addFactor(graph,factor,groupID)` adds a factor to the factor graph with group ID `groupID`. Node IDs of the same group can be retrieved by group ID using `nodeIDs` function.```

## Input Arguments

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Factor graph to add factor to, specified as a `factorGraph` object.

Factors to add to the factor graph, specified as a valid factor object.

A valid factor object must be one of these objects, and the object must not create any invalid nodes when added to the factor graph:

With the exception of `factorGPS` and `factorIMU`, you can simultaneously add multiple factors to the factor graph using any one of the listed factor objects. `factorGPS` and `factorIMU` support only single-factor addition.

If the specified factor object creates any invalid nodes, then `addFactor` adds none of the factors from the factor object.

Group IDs for nodes of the added factor, specified as any of these options:

`groupID` SizeGrouping Behavior

nonnegative integer

Assigns all nodes to one group.

For example, if you add a factor object that has a `NodeID` value of $\left[\begin{array}{cc}1& 2\\ 3& 4\end{array}\right]$ with a `groupID` value of `1`, `addFactor` adds nodes 1, 2, 3, and 4 to group 1.

two-element row vector of nonnegative integers

Specify groups for each column of nodes.

For example, if you add a factor object that has a `NodeID` value of $\left[\begin{array}{cc}1& 2\\ 3& 4\end{array}\right]$ with a `groupID` value of $\left[\begin{array}{cc}1& 2\end{array}\right]$, `addFactor` adds nodes 1 and 3 to group 1 and adds nodes 2 and 4 to group 2.

The behavior for IMU factors is different. If you add an IMU factor with a `NodeID` value of $\left[\begin{array}{cccccc}1& 2& 3& 4& 5& 6\end{array}\right]$ and `groupID` set to $\left[\begin{array}{cc}1& 2\end{array}\right]$, `addFactor` adds nodes 1, 2, and 3 to group 1 and nodes 4, 5, and 6 to group 2.

N-element column vector of nonnegative integers

Group nodes by factor, where N is the total number of factors specified by the `NodeID` property of `factor`.

For example, if you add a factor object that has a `NodeID` value of $\left[\begin{array}{cc}1& 2\\ 3& 4\end{array}\right]$ with a `groupID` value of $\left[\begin{array}{c}1\\ 2\end{array}\right]$, `addFactor` adds nodes 1 and 2 to group 1 and adds nodes 3 and 4 to group 2.

N-by-2 matrix of nonnegative integers

Add nodes in `NodeID` to the group specified at its corresponding index in `groupID`, where N is the total number of rows of the `NodeID` property of `factor`.

For example, if you add a factor object that has a `NodeID` value of $\left[\begin{array}{cc}1& 2\\ 3& 4\end{array}\right]$ with a `groupID` value of $\left[\begin{array}{cc}1& 2\\ 3& 1\end{array}\right]$, `addFactor` add nodes 1 and 4 into group 1, adds node 2 to group 2, and adds node 3 to group 3.

Note

When adding a `factorIMU` or `factorGPS` object to a factor graph, `groupID` accepts only these values:

• `factorIMU` — Nonnegative integer or a two-element row vector of nonnegative integers.

• `factorGPS` — Nonnegative integer

Adding nodes to groups enables you to query node IDs by group by specifying the `GroupID` name-value argument of the `nodeIDs` function.

## Output Arguments

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Factor IDs of the added factors, returned as an N-element row vector of nonnegative integers. N is the total number of factors added.

The function returns this argument only when it successfully adds the factors to the factor graph. If adding the factors results in an invalid node, then `addFactor` adds none of the factors from the factor object.

## Version History

Introduced in R2022a

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