Detect Drift

Update drift detector states and drift status with new data

Since R2024b

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  • Detect Drift Block Icon

Libraries:
Statistics and Machine Learning Toolbox / Incremental Learning / Drift Detection

Description

The Detect Drift block updates the internal statistics and drift status of a drift detector when given new data.

Import an initialized incremental concept drift detector object (incrementalConceptDriftDetector) into the block by specifying the name of a workspace variable that contains the object. The input port x receives a data stream for which the drift is evaluated. The input port reset receives a signal that resets the internal states of the drift detector. The output port IsWarm returns a value indicating if the drift detector is warm, which means that it tracks the drift status. The output port status returns the current drift status. The optional input port w receives observation weights.

Examples

Monitor Drift Using Detect Drift Block

Monitor Drift Using Detect Drift Block

Use the Detect Drift block for monitoring drift in a data stream in Simulink®. The block detects drift in an input datastream using a configured incremental concept drift detector (incrementalConceptDriftDetector) and outputs the drift status. The sample reset logic provided with the example enables the block to reset the internal statistics of the drift detector upon detecting a drift in the data.

Ports

Input

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Input data, specified as an n-by-1 numeric vector, where n is the number of observations, or as a logical vector. During initialization of the model:

  • If the InputType value in the call to incrementalConceptDriftDetector is "continuous", then x must be a numeric vector.

  • If the InputType value in the call to incrementalConceptDriftDetector is "binary", then x can be a logical vector.

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

Reset signal, specified as 0 (false) or 1(true or a numeric scalar. When the reset signal is a positive scalar (greater than 0), the drift detector resets the internal states of the incrementalConceptDriftDetector, including PreviousDriftStatus and DriftStatus. After a drift is detected in the data, the block resets the detector using a user-defined reset logic subsystem.

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

Observation weights, specified as a numeric vector. The Detect Drift block weights the observations in x with the corresponding values in w. The size of w must be equal to the number of observations in x.

You cannot provide observation weights for the Hoeffding's Bounds Drift Detection Method using exponentially weighted moving averages (HDDMW). To use observation weights, specify the DetectionMethod as "ddm" or "hddma" in the call to incrementalConceptDriftDetector.

Dependencies

To enable this port, select the check box for Add input port for observation weights on the Main tab of the Block Parameters dialog box.

Data Types: single | double

Output

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Flag indicating whether the Detect Drift block tracks the drift status, returned as logical 0 (false) or 1 (true).

ValueDescription
1 (true)The incrementalConceptDriftDetector object is warm. Consequently, the block tracks the drift status in the signal output.
0 (false)The incrementalConceptDriftDetector object is not warm. Consequently, the block only updates the internal statistics and does not track the drift status.

Data Types: Boolean

Current drift status, specified as 0 (stable, or no drift), 1 (drift warning) or 2 (drift detected).

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

Parameters

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To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Main

Specify the name of a workspace variable that contains the configured incrementalConceptDriftDetector object.

Programmatic Use

Block Parameter: DriftDetector
Type: character vector or string
Values: incrementalConceptDriftDetector object name
Default: "IncCDDetector"

Select the check box to include the input port w for observation weights in the Detect Drift block.

Programmatic Use

Block Parameter: ShowInputWeights
Type: character vector
Values: "off" | "on"
Default: "off"

Specify the discrete interval between sample time hits or specify another type of sample time, such as continuous (0) or inherited (–1). For more options, see Types of Sample Time (Simulink).

By default, the Detect Drift block inherits sample time based on the context of the block within the model.

Programmatic Use

Block Parameter: SystemSampleTime
Type: string scalar or character vector
Values: scalar
Default: "–1"

Data Types

Fixed-Point Operational Parameters

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

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

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 the 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 value causing the overflow 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 drift status 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 the data type.

For more information about data types, see Control Data Types of Signals (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: DriftStatusDataTypeStr
Type: character vector or string
Values: "Inherit: auto" | "double" | "single" | "half" | "int8" | "uint8" | "int16" | "uint16" | "int32" | "uint32" | "int64" | "uint64" | "boolean" | "fixdt(1,16,0)" | "fixdt(1,16,2^0,0)" | "<data type expression>"
Default: "Inherit: auto"

Specify the lower value of the drift status range that Simulink checks.

Simulink uses the minimum value to perform:

Programmatic Use

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

Specify the upper value of the drift status range that Simulink checks.

Simulink uses the maximum value to perform:

Programmatic Use

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

Specify the data type of the mean (moving average of input observations). The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

For more information about data types, see Control Data Types of Signals (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: MeanDataTypeStr
Type: character vector or string
Values: "Inherit: auto" | "double" | "single" | "half" | "int8" | "uint8" | "int16" | "uint16" | "int32" | "uint32" | "int64" | "uint64" | "boolean" | "fixdt(1,16,0)" | "fixdt(1,16,2^0,0)" | "<data type expression>"
Default: "Inherit: auto"

Specify the lower value of the mean range that Simulink checks.

Simulink uses the minimum value to perform:

Programmatic Use

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

Specify the upper value of the mean range that Simulink checks.

Simulink uses the maximum value to perform:

Programmatic Use

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

Specify the data type of the variance (moving variance of input observations). The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

For more information about data types, see Control Data Types of Signals (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: VarianceDataTypeStr
Type: character vector or string
Values: "Inherit: auto" | "double" | "single" | "half" | "int8" | "uint8" | "int16" | "uint16" | "int32" | "uint32" | "int64" | "uint64" | "boolean" | "fixdt(1,16,0)" | "fixdt(1,16,2^0,0)" | "<data type expression>"
Default: "Inherit: auto"

Specify the lower value of the variance range that Simulink checks.

Simulink uses the minimum value to perform:

Programmatic Use

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

Specify the upper value of the variance range that Simulink checks.

Simulink uses the maximum value to perform:

Programmatic Use

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

Specify the data type of the weights sum (moving sum of weighted input observations). The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

For more information about data types, see Control Data Types of Signals (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: WeightsSumDataTypeStr
Type: character vector or string
Values: "Inherit: auto" | "double" | "single" | "half" | "int8" | "uint8" | "int16" | "uint16" | "int32" | "uint32" | "int64" | "uint64" | "boolean" | "fixdt(1,16,0)" | "fixdt(1,16,2^0,0)" | "<data type expression>"
Default: "Inherit: auto"

Specify the lower value of the weights sum range that Simulink checks.

Simulink uses the minimum value to perform:

Programmatic Use

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

Specify the upper value of the weights sum range that Simulink checks.

Simulink uses the maximum value to perform:

Programmatic Use

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

Block Characteristics

Data Types

Boolean | double | enumerated | fixed point | half | integer | single

Direct Feedthrough

yes

Multidimensional Signals

no

Variable-Size Signals

no

Zero-Crossing Detection

no

Extended Capabilities

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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™.

Version History

Introduced in R2024b

See Also

Blocks

Objects

Functions