resume
Resume training of classification ensemble model
Description
specifies additional options using one or more name-value arguments. For example,
you can track the number of weak learners as they are trained, and set options for
computing in parallel.ens1
= resume(ens
,nlearn
,Name=Value
)
Examples
Train Classification Ensemble for Additional Cycles
Train a classification ensemble for three cycles, and compare the resubstitution error obtained after training the ensemble for more cycles.
Load the ionosphere
data set.
load ionosphere
Train a classification ensemble for three cycles and examine the resubstitution error.
ens = fitcensemble(X,Y,Method="GentleBoost",NumLearningCycles=3);
L = resubLoss(ens)
L = 0.0085
Train for three more cycles and examine the new resubstitution error.
ens1 = resume(ens,3); L = resubLoss(ens1)
L = 0
The resubstitution error is much lower in the new ensemble than the original.
Input Arguments
ens
— Classification ensemble model
ClassificationEnsemble
model object | ClassificationBaggedEnsemble
model object
Classification ensemble model, specified as a ClassificationEnsemble
or
ClassificationBaggedEnsemble
model object trained with fitcensemble
.
Note
You cannot resume training when ens
is a model
trained with these options set for fitcensemble
:
Method
="Subspace"
and
NumLearningCycles
="AllPredictorCombinations"
.
nlearn
— Number of additional training cycles
positive integer
Number of additional training cycles for ens
, specified as a positive
integer.
Data Types: double
| single
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.
Before R2021a, use commas to separate each name and value, and enclose
Name
in quotes.
Example: resume(ens,10,NPrint=5,Options=statset(UseParallel=true))
specifies to train ens
for an additional 10 cycles, display a
message to the command line every time resume
finishes
training 5 weak learners, and to perform computations in parallel.
NPrint
— Printout frequency
"off"
(default) | positive integer
Printout frequency, specified as a positive integer
m
or "off"
.
resume
displays a message to the command
line every time it finishes training m
weak learners.
If you specify "off"
,
resume
does not display a message when it
completes training weak learners.
Tip
For the fastest training of some boosted decision trees, when the
classification Method
is
"AdaBoostM1"
,
"AdaBoostM2"
, "GentleBoost"
,
or "LogitBoost"
, set NPrint
to "off"
(the default value).
Example: NPrint=5
Data Types: single
| double
| char
| string
Options
— Options for computing in parallel and setting random number streams
structure
Options for computing in parallel and setting random number streams, specified as a
structure. Create the Options
structure using statset
.
Note
You need Parallel Computing Toolbox™ to run computations in parallel.
You can use the same parallel options for resume
as you used for the
original training. Use the Options
argument to change the parallel options,
as needed. This table describes the option fields and their values.
Field Name | Value | Default |
---|---|---|
UseParallel | Set this value to | false |
UseSubstreams | Set this value to To compute reproducibly, set
| false |
Streams | Specify this value as a RandStream object or cell array of such objects. Use a single object
except when the UseParallel value is true and
the UseSubstreams value is false . In that case,
use a cell array that has the same size as the parallel pool. | If you do not specify Streams ,
resume uses the default stream or streams. |
For dual-core systems and above, resume
parallelizes training
using Intel® Threading Building Blocks (TBB). Therefore, setting
UseParallel
to true
might not provide a significant
increase in speed on a single computer. For details on Intel TBB, see https://www.intel.com/content/www/us/en/developer/tools/oneapi/onetbb.html.
Example: Options=statset(UseParallel=true)
Data Types: struct
Extended Capabilities
Automatic Parallel Support
Accelerate code by automatically running computation in parallel using Parallel Computing Toolbox™.
resume
supports parallel training
using the 'Options'
name-value argument. Create options using statset
, such as options = statset('UseParallel',true)
.
Parallel ensemble training requires you to set the 'Method'
name-value
argument to 'Bag'
. Parallel training is available only for tree learners, the
default type for 'Bag'
.
GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.
This function fully supports GPU arrays. For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).
Version History
Introduced in R2011a
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