Main Content

Simulink.sdi.compareSignals

Compare data in two Simulink.sdi.Signal objects

collapse all in page

Syntax

diff = Simulink.sdi.compareSignals(sigID1,sigID2)
diff = Simulink.sdi.compareSignals(sigID1,sigID2,Name=Value)

Description

diff = Simulink.sdi.compareSignals(sigID1,sigID2) compares the signals that correspond to the signal IDs sigID1 and sigID2 and returns the results in a Simulink.sdi.DiffSignalResult object. For more information on how the comparison results are computed, see How the Simulation Data Inspector Compares Data.

example

diff = Simulink.sdi.compareSignals(sigID1,sigID2,Name=Value) compares the signals that correspond to the signal IDs sigID1 and sigID2 using the options specified by one or more name-value arguments. (since R2023a)

Examples

collapse all

Open Live Script

You can use the Simulation Data Inspector programmatic interface to compare signals within a single run. This example compares the input and output signals of an aircraft longitudinal flight controller.

Load the Simulation Data Inspector session file that contains the flight control data.

Simulink.sdi.load("AircraftExample.mldatx");

To access the latest run, use the Simulink.sdi.Run.getLatest function.

aircraftRun = Simulink.sdi.Run.getLatest;

Use the Simulink.sdi.getSignalsByName function to access the Stick signal, which represents the input to the controller, and the alpha, rad signal, which represents the output.

stick = getSignalsByName(aircraftRun,"Stick");
alpha = getSignalsByName(aircraftRun,"alpha, rad");

Use the signal IDs to compare the Stick and alpha, rad signals using the Simulink.sdi.compareSignals function. The Stick signal is the baseline. The alpha, rad signal is the signal to compare against the baseline.

comparisonResults = Simulink.sdi.compareSignals(stick.ID,alpha.ID);
match = comparisonResults.Status
match = 
  ComparisonSignalStatus enumeration

    OutOfTolerance

The comparison result is out of tolerance. You can use the Simulink.sdi.view function to open the Simulation Data Inspector to view and analyze the comparison results.

Simulink.sdi.view

Comparison of the stick and alpha, rad signals

You can specify time and magnitude tolerance values to use for the comparison. Comparisons use tolerance values specified for the baseline signal in the comparison. To account for the phase shift, set a time tolerance of 1 on the Stick signal. To account for magnitude differences, set an absolute tolerance value of 0.1 on the Stick signal.

stick.TimeTol = 1;
stick.AbsTol = 0.1;

Compare the signals again. This time, because of the absolute and time tolerances, the signal comparison passes.

comparisonResults = Simulink.sdi.compareSignals(stick.ID,alpha.ID);
match = comparisonResults.Status
match = 
  ComparisonSignalStatus enumeration

    WithinTolerance

Comparison of the Stick and alpha, rad signals using a time tolerance of 1 and an absolute tolerance of 0.1

Open Live Script

This example shows how to compare signals from different simulation runs using the Simulation Data Inspector's Simulink.sdi.compareSignals function. When you only have one signal of interest to compare, using a signal comparison returns the Simulink.sdi.diffSignalResult object with the comparison data directly.

Generate Simulation Data

Use the slexAircraftExample model to generate simulation runs. Between the runs, change the time constant of the input filter.

% Load example model
load_system('slexAircraftExample')

% Mark the alpha, rad signal for streaming
Simulink.sdi.markSignalForStreaming('slexAircraftExample/Aircraft Dynamics Model',4,'on')

% Simulate system
out_1 = sim('slexAircraftExample');

% Change input filter time constant
modelWorkspace = get_param('slexAircraftExample','modelworkspace');
assignin(modelWorkspace,'Ts',0.2)

% Simulate again
out_2 = sim('slexAircraftExample');

Get Signal IDs for the Signal Comparison

Create run objects using the run IDs, and then use getSignalIDByIndex to get the signal IDs to pass to Simulink.sdi.compareSignals.

% Get run data
runIDs = Simulink.sdi.getAllRunIDs;

runID1 = runIDs(end-1);
runID2 = runIDs(end);

run1 = Simulink.sdi.getRun(runID1);
run2 = Simulink.sdi.getRun(runID2);

sigID1 = getSignalIDByIndex(run1,1);
sigID2 = getSignalIDByIndex(run2,1);

Compare Signals

Compare the signals, and open the Simulation Data Inspector to view the results.

diffResult = Simulink.sdi.compareSignals(sigID1,sigID2);

Simulink.sdi.view

Input Arguments

collapse all

Signal ID of baseline signal, specified as an integer. The Simulation Data Inspector assigns a signal ID to each signal when a run is created. You can get the signal ID for a signal using one of these functions:

Signal ID of signal to compare, specified as an integer. The Simulation Data Inspector assigns a signal ID to each signal when a run is created. You can get the signal ID for a signal using one of these functions:

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: diff = Simulink.sdi.compareSignals(sigID1,sigID2,DataType="MustMatch")

Comparison sensitivity to signal data types, specified as "MustMatch". Specify DataType="MustMatch" when you want the comparison to be sensitive to numeric data type mismatches in compared signals.

When signal data types do not match, the Status property of the Simulink.sdi.DiffSignalResult object for the result is set to DataTypeMismatch.

The Simulink.sdi.compareSignals function compares the data types before synchronizing and comparing the signal data. When you do not specify this name-value argument, the comparison checks data types only to detect a comparison between string and numeric data. For a comparison between string and numeric data, results are not computed, and the status for the result is DataTypeMismatch. For signals that have different numeric data types, the comparison computes results.

When you configure the comparison to stop on the first mismatch, a data type mismatch stops the comparison.

Comparison sensitivity to signal time vectors, specified as "MustMatch". Specify Time="MustMatch" when you want the comparison to be sensitive to mismatches in the time vectors of compared signals. When you specify this name-value argument, the algorithm compares the time vectors before synchronizing and comparing the signal data.

When the time vectors do not match, the Status property of the Simulink.sdi.DiffSignalResult object for the result is set to TimeMismatch.

Comparisons are not sensitive to differences in signal time vectors unless you specify this name-value argument. For comparisons that are not sensitive to differences in the time vectors, the comparison algorithm synchronizes the signals prior to the comparison. For more information about how synchronization works, see How the Simulation Data Inspector Compares Data.

When you specify that time vectors must match and configure the comparison to stop on the first mismatch, a time vector mismatch stops the comparison.

Comparison sensitivity to signal start and stop times, specified as "MustMatch". Specify StartStop="MustMatch" when you want the comparison to be sensitive to mismatches in signal start and stop times. When you specify this name-value argument, the algorithm compares the start and stop times for each signal before synchronizing and comparing the signal data.

When the start times and stop times do not match, the Status property of the Simulink.sdi.DiffSignalResult object for the result is set to StartStopMismatch.

When you specify that start and stop times must match and configure the comparison to stop on the first mismatch, a start or stop time mismatch stops the comparison.

Whether comparison stops on first detected mismatch, specified as "Metadata" or "Any". A stopped comparison may not compute results for all channels when comparing multidimensional signals and can return a mismatched result more quickly.

  • "Metadata" — A mismatch in metadata stops the comparison. Metadata comparisons happen before signal data comparisons.

    The Simulation Data Inspector always compares signal units. When you configure the comparison to stop on the first mismatch, mismatched units always stop the comparison. You can specify additional name-value arguments to configure the comparison to check and stop on the first mismatch for additional metadata, such as signal data type, start and stop times, and time vectors.

  • "Any" — A mismatch in metadata or signal data stops the comparison.

Whether to compute comparison results for each channel in multidimensional signals, specified as logical true (1) or false (0).

  • true or 1 — Comparison expands multidimensional signals represented as a single signal with nonscalar sample values to a set of signals with scalar sample values and computes a comparison result for each signal.

    The representation of the multidimensional signal in the Simulation Data Inspector as a single signal with nonscalar sample values does not change.

  • false or 0 — Comparison does not compute results for multidimensional signals represented as a single signal with nonscalar sample values.

Output Arguments

collapse all

Signal comparison result, returned as a Simulink.sdi.DiffSignalResult object. Complex signal comparison results are returned as an array of two DiffSignalResult objects. One DiffSignalResult object contains the real data and the other contains the imaginary data. Check the Name property of the DiffSignalResult object to determine whether it contains real or imaginary data.

Limitations

The Simulation Data Inspector does not support comparing:

  • Before R2020a: Signals of data types int64 or uint64.

  • Variable-size signals.

If you perform multiple signal comparisons or run comparisons, only the latest DiffSignalResult object has visible properties.

Version History

Introduced in R2011b

See Also

Objects

Functions

Tools

Topics