Main Content

ClassificationSVM Predict

Classify observations using support vector machine (SVM) classifier for one-class and binary classification

  • Library:
  • Statistics and Machine Learning Toolbox / Classification

Description

The ClassificationSVM Predict block classifies observations using an SVM classification object ClassificationSVM and its object function predict for one-class and two-class (binary) classification.

Import a trained SVM classification object into the block by specifying the name of a workspace variable that contains a ClassificationSVM object. The input port X receives an observation (predictor data), and the output port Label returns a predicted class label for the observation. You can add an optional output port Score that returns predicted class scores or posterior probabilities.

Ports

Input

expand all

Predictor data, specified as a column vector or row vector of one observation.

Dependencies

  • The variables in X must have the same order as the predictor variables that trained the SVM model specified by Select trained machine learning model.

  • If you set 'Standardize',true in fitcsvm when training the SVM model, then the ClassificationSVM Predict block standardizes the values of X using the means and standard deviations in the Mu and Sigma properties (respectively) of the SVM model.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point

Output

expand all

Predicted class label, returned as a scalar.

Dependencies

  • For one-class learning, Label is the value representing the positive class.

  • For two-class learning, Label is the class yielding the largest score or the largest posterior probability.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated

Predicted class scores or posterior probabilities, returned as a scalar for one-class learning or a 1-by-2 vector for two-class learning.

  • For one-class learning, Score is the classification score of the positive class. You cannot obtain posterior probabilities for one-class learning.

  • For two-class learning, Score is a 1-by-2 vector.

    • The first and second element of Score correspond to the classification scores of the negative class (svmMdl.ClassNames(1)) and the positive class (svmMdl.ClassNames(2)), respectively, where svmMdl is the SVM model specified by Select trained machine learning model. You can use the ClassNames property of svmMdl to check the negative and positive class names.

    • If you fit the optimal score-to-posterior-probability transformation function using fitPosterior or fitSVMPosterior, then Score contains class posterior probabilities. Otherwise, Score contains class scores.

Dependencies

To enable this port, select the check box for Add output port for predicted class scores on the Main tab of the Block Parameters dialog box.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point

Parameters

expand all

Main

Specify the name of a workspace variable that contains a ClassificationSVM object or CompactClassificationSVM object.

When you train the SVM model by using fitcsvm, the following restrictions apply:

  • The predictor data cannot include categorical predictors (logical, categorical, char, string, or cell). If you supply training data in a table, the predictors must be numeric (double or single). Also, you cannot use the 'CategoricalPredictors' name-value pair argument. To include categorical predictors in an SVM model, preprocess the categorical predictors by using dummyvar before fitting the SVM model.

  • The value of the 'ScoreTransform' name-value pair argument cannot be 'invlogit' or an anonymous function. For a block that predicts posterior probabilities given new observations, pass a trained SVM model to fitPosterior or fitSVMPosterior.

  • The value of the 'KernelFunction' name-value pair argument must be 'gaussian', 'linear', or 'polynomial'.

Programmatic Use

Block Parameter: TrainedLearner
Type: workspace variable
Values: ClassificationSVM object | CompactClassificationSVM object
Default: svmMdl

Select the check box to include the second output port Score in the ClassificationSVM Predict block.

Programmatic Use

Block Parameter: ShowOutputScore
Type: character vector
Values: 'off' | 'on'
Default: 'off'

Data Types

Fixed-Point Operational Parameters

Specify the rounding mode for fixed-point operations. For more information, see Rounding (Fixed-Point Designer).

Block parameters always round to the nearest representable value. To control the rounding of a block parameter, enter an expression using a MATLAB® rounding function into the mask field.

Programmatic Use

Block Parameter: RndMeth
Type: character vector
Values: 'Ceiling' | 'Convergent' | 'Floor' | 'Nearest' | 'Round' | 'Simplest' | 'Zero'
Default: 'Floor'

Specify whether overflows saturate or wrap.

ActionRationaleImpact on OverflowsExample

Select this check box (on).

Your model has possible overflow, and you want explicit saturation protection in the generated code.

Overflows saturate to either the minimum or maximum value that the data type can represent.

The maximum value that the int8 (signed 8-bit integer) data type can represent is 127. Any block operation result greater than this maximum value causes overflow of the 8-bit integer. With the check box selected, the block output saturates at 127. Similarly, the block output saturates at a minimum output value of –128.

Clear this check box (off).

You want to optimize efficiency of your generated code.

You want to avoid overspecifying how a block handles out-of-range signals. For more information, see Troubleshoot Signal Range Errors (Simulink).

Overflows wrap to the appropriate value that the data type can represent.

The maximum value that the int8 (signed 8-bit integer) data type can represent is 127. Any block operation result greater than this maximum value causes overflow of the 8-bit integer. With the check box cleared, the software interprets the overflow causing value as int8, which can produce an unintended result. For example, a block result of 130 (binary 1000 0010) expressed as int8 is –126.

Programmatic Use

Block Parameter: SaturateOnIntegerOverflow
Type: character vector
Values: 'off' | 'on'
Default: 'off'

Select this parameter to prevent the fixed-point tools from overriding the data type you specify for the block. For more information, see Use Lock Output Data Type Setting (Fixed-Point Designer).

Programmatic Use

Block Parameter: LockScale
Type: character vector
Values: 'off' | 'on'
Default: 'off'
Data Type

Specify the data type for the Label output. The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

When you select an inherited option, the software behaves as follows:

  • Inherit: Inherit via back propagation — Simulink automatically determines the Label data type of the block during data type propagation (see Data Type Propagation (Simulink)). In this case, the block uses the data type of a downstream block or signal object.

  • Inherit: Inherit from 'Constant value' — The ClassificationSVM predict block uses a Constant block under the mask. The data type of the Constant block depends on the observed class labels that trained the SVM model specified by Select trained machine learning model.

    • If the observed class labels are numeric, then the Constant block data type is double.

    • If the observed class labels are logical, then the Constant block data type is boolean.

    • If the observed class labels are not numeric or logical, then the Constant block uses an enumerated data type variable enumLabels. For example, if the class labels are class 1 and class 2, then the corresponding Label values are enumLabels.class_1 and enumLabels.class_2. The block converts the class labels to valid MATLAB identifiers by using the matlab.lang.makeValidName function.

For more information about data types, see Control Signal Data Types (Simulink).

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Programmatic Use

Block Parameter: LabelDataTypeStr
Type: character vector
Values: 'Inherit: Inherit via back propagation' | Inherit: Inherit from 'Constant value' | 'double' | 'single' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | boolean | 'fixdt(1,16)' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | Enum: <class name> | '<data type expression>'
Default: 'Inherit: Inherit via back propagation'

Lower value of the Label output range that Simulink® checks.

Simulink uses the minimum value to perform:

Note

The Label minimum parameter does not saturate or clip the actual Label output signal. Use the Saturation (Simulink) block instead.

Programmatic Use

Block Parameter: LabelOutMin
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Upper value of the Label output range that Simulink checks.

Simulink uses the maximum value to perform:

Note

The Label maximum parameter does not saturate or clip the actual Label output signal. Use the Saturation (Simulink) block instead.

Programmatic Use

Block Parameter: LabelOutMax
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Specify the data type for the Score output. The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

When you select Inherit: auto, the block uses a rule that inherits a data type.

For more information about data types, see Control Signal Data Types (Simulink).

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Programmatic Use

Block Parameter: ScoreDataTypeStr
Type: character vector
Values: 'Inherit: auto' | 'double' | 'single' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | 'fixdt(1,16)' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | '<data type expression>'
Default: 'double'

Lower value of the Score output range that Simulink checks.

Simulink uses the minimum value to perform:

Note

The Score minimum parameter does not saturate or clip the actual Score signal. Use the Saturation (Simulink) block instead.

Programmatic Use

Block Parameter: ScoreOutMin
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Upper value of the Score output range that Simulink checks.

Simulink uses the maximum value to perform:

Note

The Score maximum parameter does not saturate or clip the actual Score signal. Use the Saturation (Simulink) block instead.

Programmatic Use

Block Parameter: ScoreOutMax
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Specify the data type for the internal untransformed scores. The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

When you select Inherit: auto, the block uses a rule that inherits a data type.

For more information about data types, see Control Signal Data Types (Simulink).

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Programmatic Use

Block Parameter: RawScoreDataTypeStr
Type: character vector
Values: 'Inherit: auto' | 'double' | 'single' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | 'fixdt(1,16)' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | '<data type expression>'
Default: 'double'

Lower value of the untransformed score range that Simulink checks.

Simulink uses the minimum value to perform:

Note

The Raw score minimum parameter does not saturate or clip the actual untransformed score signal.

Programmatic Use

Block Parameter: RawScoreOutMin
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Upper value of the untransformed score range that Simulink checks.

Simulink uses the maximum value to perform:

Note

The Raw score maximum parameter does not saturate or clip the actual untransformed score signal.

Programmatic Use

Block Parameter: RawScoreOutMax
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Specify the data type of a parameter for kernel computation.

The Kernel data type paramter specifies the data type of a different parameter depending on the type of kernel function of the specified SVM model. You specify the 'KernelFunction' name-value pair argument when training the SVM model.

'KernelFunction' valueData Type
'gaussian' or 'rbf'Kernel data type specifies the data type of the squared distance D2=xs2 for the Gaussian kernel G(x,s)=exp(D2), where x is the predictor data for an observation and s is a support vector.
'linear'Kernel data type specifies the data type for the output of the linear kernel function G(x,s)=xs', where x is the predictor data for an observation and s is a support vector.
'polynomial'Kernel data type specifies the data type for the output of the polynomial kernel function G(x,s)=(1+xs')p, where x is the predictor data for an observation, s is a support vector, and p is a polynomial kernel function order.

The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

When you select an inherited option, the software behaves as follows:

  • Inherit: Inherit via internal rule — The block uses an internal rule to determine its data type. The internal rule chooses a data type that optimizes numerical accuracy, performance, and generated code size, while taking into account the properties of the embedded target hardware. The software cannot simultaneously optimize efficiency and numerical accuracy in all situations.

  • Inherit: Keep MSB — Simulink chooses a data type that maintains the full range of the operation, and then reduces the precision to a size appropriate for the embedded target hardware. This rule never produces overflows.

    Tip

    For more efficient generated code, clear the Saturate on integer overflow parameter.

  • Inherit: Match scaling — Simulink chooses a data type whose scaling matches the scaling of the input types, where the input refers to an input of a block under the mask. If the full range of the type does not fit on the embedded target hardware, the software reduces the range to yield a type that is appropriate for the embedded target hardware. This rule can produce overflows.

    The software cannot simultaneously optimize code efficiency and numerical accuracy in all situations. If these internal rules do not meet your specific needs for numerical accuracy or performance, use one of the following options:

    • Specify the data type explicitly.

    • Specify a default data type explicitly, such as fixdt(1,32,16), and then use the Fixed-Point Tool to propose data types for your model. For more information, see fxptdlg (Fixed-Point Designer).

  • Inherit: Inherit via back propagation — (Not recommended) The block uses the data type of a downstream block under the mask.

  • Inherit: Same as first input — (Not recommended) This first input refers to the first input of a block under the mask.

For more information about data types, see Control Signal Data Types (Simulink).

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Programmatic Use

Block Parameter: KernelDataTypeStr
Type: character vector
Values: 'Inherit: Inherit via internal rule | 'Inherit: Keep MSB' | 'Inherit: Match scaling' | 'double' | 'single' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'uint64' | 'int64' | 'fixdt(1,16)' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | '<data type expression>'
Default: 'double'

Lower value of the kernel computation internal variable range that Simulink checks.

Simulink uses the minimum value to perform:

Note

The Kernel minimum parameter does not saturate or clip the actual kernel computation value signal.

Programmatic Use

Block Parameter: KernelOutMin
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Upper value of the kernel computation internal variable range that Simulink checks.

Simulink uses the maximum value to perform:

Note

The Kernel maximum parameter does not saturate or clip the actual kernel computation value signal.

Programmatic Use

Block Parameter: KernelOutMax
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

More About

expand all

Tips

  • If you are using a linear SVM model and it has many support vectors, then prediction (classifying observations) can be slow. To efficiently classify observations based on a linear SVM model, remove the support vectors from the ClassificationSVM object by using discardSupportVectors.

Alternative Functionality

You can use a MATLAB Function block with the predict object function of the ClassificationSVM object. For an example, see Predict Class Labels Using MATLAB Function Block.

When deciding whether to use the ClassificationSVM Predict block in the Statistics and Machine Learning Toolbox™ library or a MATLAB Function block with the predict function, consider the following:

  • If you use the Statistics and Machine Learning Toolbox library block, you can use the Fixed-Point Tool (Fixed-Point Designer) to convert a floating-point model to fixed point.

  • Support for variable-size arrays must be enabled for a MATLAB Function block with the predict function.

  • If you use a MATLAB Function block, you can use MATLAB functions for preprocessing or post-processing before or after predictions in the same MATLAB Function block.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Introduced in R2020b