growTrees

R2026b

Train additional trees and add to ensemble

Syntax

B = growTrees(B,ntrees)
B = growTrees(B,ntrees,'param1',val1,'param2',val2,...)


Description

B = growTrees(B,ntrees) grows ntrees new trees and appends them to those trees already stored in the ensemble B.

B = growTrees(B,ntrees,'param1',val1,'param2',val2,...) specifies optional parameter name/value pairs:

'NumPrint'

Specifies that a diagnostic message showing training progress should display after every value training cycles (grown trees). Default is no diagnostic messages.

'Options'

A struct that specifies options that govern computation when growing the ensemble of decision trees. One option requests that the computation of decision trees on multiple bootstrap replicates uses multiple processors, if the Parallel Computing Toolbox™ is available. Two options specify the random number streams to use in selecting bootstrap replicates. You can create this argument with a call to statset. You can retrieve values of the individual fields with a call to statget. Applicable statset parameters are: 'UseParallel' — Option to perform computations in parallel, specified as "off", "auto", or "on". Set this value to "auto" or "on" to run computations in parallel. If you specify "auto", MATLAB® uses a parallel pool if one is available, otherwise runs in serial. If you specify "on", MATLAB uses a parallel pool if one is available, otherwise throws an error. The default is "off". For dual-core systems and above, TreeBagger parallelizes training using Intel® Threading Building Blocks (TBB). Therefore, using the 'UseParallel' option on a single computer may not speed up computation much and may consume more memory than in serial. For details on Intel TBB, see https://www.intel.com/content/www/us/en/developer/tools/oneapi/onetbb.html. UseSubstreams — Set to true to compute in a reproducible fashion. Default is false. To compute reproducibly, set Streams to a type allowing substreams: 'mlfg6331_64' or 'mrg32k3a'. Streams — A RandStream object or cell array of such objects. If you do not specify Streams, growTrees uses the default stream or streams. If you choose to specify Streams, use a single object except in the case UseParallel is "on" or "auto" UseSubstreams is false In that case, use a cell array the same size as the Parallel pool.

Extended Capabilities

Automatic Parallel Support

Accelerate code by automatically running computation in parallel using Parallel Computing Toolbox™.

The growTrees function has automatic parallel support. To run computations in parallel, specify the Options name-value argument and set the UseParallel field of the options structure to "on" or "auto" using statset:

Options=statset(UseParallel="auto")

For more information, see Run MATLAB Functions with Automatic Parallel Support (Parallel Computing Toolbox).

Version History

R2026b: Enhanced control over parallel execution with UseParallel option

The UseParallel field of the Options name-value argument now accepts "off", "auto", or "on" values instead of true or false. This change gives you more control over when to use a parallel pool for parallel execution. Specifying the UseParallel field as true or false is not recommended.

This table shows how to update your code depending on your goal.

Goal	Not Recommended	Recommended
Write code that runs on the MATLAB client.	Options=statset(UseParallel=false)	Options=statset(UseParallel="off")
Write portable code that runs on a parallel pool and, if a pool is not available, runs on the MATLAB client.	Options=statset(UseParallel=true)	Options=statset(UseParallel="auto")
Write code that runs on a parallel pool and errors if a pool is not available.	N/A	Options=statset(UseParallel="on")

There are no plans to remove support for the true or false values.