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nodeIDs

Get node IDs in factor graph

Since R2022a

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Syntax

ids = nodeIDs(fg)
ids = nodeIDs(fg,Name=Value)

Description

The nodeIDs function gets all node IDs or gets a subset of node IDs from a factor graph for nodes of the same node type, group ID, or connect to factors of the same factor type.

ids = nodeIDs(fg) gets all node IDs currently in the factor graph.

ids = nodeIDs(fg,Name=Value) specifies options using one or more name-value arguments.

example

Examples

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Open Live Script

This example shows four ways of querying a factor graph for node IDs.

Create a factor graph containing four SE(3) pose nodes.

fg = factorGraph;
poseIDs = generateNodeID(fg,3,"factorTwoPoseSE3")
poseIDs = 3×2

     0     1
     1     2
     2     3


poseFactors = factorTwoPoseSE3(poseIDs);

Create group IDs that will put node IDs 0 and 1 into group 1, and node IDs 2 and 3 into group 2.

group = [1 1;
         1 2;
         2 2];
addFactor(fg,poseFactors,group);

Create and add a landmark factor connecting node 3 to a new node 4. Add both nodes to group 3. Note that nodes can exist in more than one group at the same time.

lmFactor = factorPoseSE3AndPointXYZ([3 4]);
addFactor(fg,lmFactor,3);

Get All IDs in Factor Graph

Use nodeIDs to get all the IDs in the factor graph by specifying no additional arguments other than the factor graph.

idAll = nodeIDs(fg)
idAll = 1×5

     0     1     2     3     4

Get Node IDs by Node Type

Use nodeIDs and specify the NodeType name-value argument as "POSE_SE3" to get all of the SE(3) pose nodes.

idByNode = nodeIDs(fg,NodeType="POSE_SE3")
idByNode = 1×4

     0     1     2     3

Get Node IDs by Factor Type

Use nodeIDs and specify the FactorType name-value argument as "factorPoseSE3AndPointXYZ" to get all of the nodes related by a factorPoseSE3AndPointXYZ factor.

idByFactor = nodeIDs(fg,FactorType="factorPoseSE3AndPointXYZ")
idByFactor = 1×2

     3     4

Get Node IDs by Group ID

Use nodeIDs and specify the FactorType name-value argument as "factorTwoPoseSE3" to get all of the nodes related by a factorTwoPoseSE3 factor.

idGroup1 = nodeIDs(fg,GroupID=1)
idGroup1 = 1×2

     0     1


idGroup2 = nodeIDs(fg,GroupID=2)
idGroup2 = 1×2

     2     3


idGroup3 = nodeIDs(fg,GroupID=3)
idGroup3 = 1×2

     3     4

Input Arguments

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Factor graph, specified as a factorGraph object.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: nodeIDs(fg,GroupID=1) retrieves all of the node IDs of factor graph fg that are associated with group 1.

Node type of the desired nodes in the factor graph, specified as one of these options:

  • "POSE_SE2" — Pose in SE(2) state space

  • "POSE_SE3" — Pose in SE(3) state space

  • "VEL3" — 3-D velocity

  • "POINT_XY" — 2-D point

  • "POINT_XYZ" — 3-D point

  • "IMU_BIAS" — IMU gyroscope and accelerometer bias

Example: nodeIDs(fg,NodeType="POSE_SE2") retrieves all of the node IDs of nodes that are of node type POSE_SE2.

Data Types: char | string

Factor type that the nodes relate to in the factor graph, specified as one of these options:

Example: nodeIDs(fg,FactorType="factorTwoPoseSE2") retrieves all of the node IDs of nodes that relate to factors of type factorTwoPoseSE2.

Data Types: char | string

Group ID of desired nodes, specified as a nonnegative integer or N-element row vector of nonnegative integers. N is the number of groups.

If GroupID is an N-element row vector of nonnegative integers, there must be no duplicate group IDs in the vector.

To add nodes to a group, specify the group using the groupID argument of the addFactor function.

Example: nodeIDs(fg,GroupID=4) retrieves all of the node IDs of nodes that are in group 4.

Output Arguments

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Node IDs of all nodes that fit the specified criteria within the specified factorGraph object, returned as an N-element row vector. N is the number of returned nodes. Note that the node IDs may not be continuous within the vector.

Extended Capabilities

Version History

Introduced in R2022a

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See Also

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