日志大数据模型

Open the example modelsldemo_fuelsys.

open_system('sldemo_fuelsys')

SelectConfiguration Parameters > Data Import/Export > Log Dataset data to file.

set_param('sldemo_fuelsys','LoggingToFile','on')

Simulate the model.

sim('sldemo_fuelsys')

The MAT-fileout.matappears in your current folder. The file contains data for logged signals such asfuel(which is at the root level of the model).

一个t the command prompt, create aDatasetRefobject that refers to the logging variable by name,sldemo_fuelsys_output.

DSRef = Simulink.SimulationData.DatasetRef('out.mat','sldemo_fuelsys_output');

Preview Big Data

Use curly braces ({and}) to extract the signal elementfuel, which is the tenth element inDSRef, as aSimulink.SimulationData.Signalobject that contains aSimulationDatastoreobject.

SimDataSig = DSRef{10};

To more easily interact with theSimulationDatastoreobject that resides in theValuesproperty of theSignalobject, store a handle in a variable namedDStore.

DStore = SimDataSig.Values;

Use thepreviewmethod to inspect the first five samples of logged data for thefuelsignal.

preview(DStore)

ans = 10x1 timetable Time Data ______________ ______ 0 sec 1.209 0.00056199 sec 1.209 0.0033719 sec 1.209 0.01 sec 1.1729 0.02 sec 1.1409 0.03 sec 1.1124 0.04 sec 1.0873 0.05 sec 1.0652 0.055328 sec 1.0652 0.055328 sec 1.0652

Inspect Specific Sample

Inspect the 603rd sample of loggedfueldata.

Set theReadSizeproperty ofDStoreto a number that, considering memory resources, your computer can tolerate. For example, setReadSizeto200.

DStore.ReadSize = 200;

Read from the datastore three times. Each read operation advances the reading position by 200 samples.

read(DStore); read(DStore); read(DStore);

Now that you are very close to the 603rd sample, setReadSizeto a smaller number. For example, setReadSizeto5.

DStore.ReadSize = 5;

Read from the datastore again.

read(DStore)

ans = 5x1 timetable Time Data ________ ______ 5.79 sec 1.6097 5.8 sec 1.6136 5.81 sec 1.6003 5.82 sec 1.5904 5.83 sec 1.5832

The third sample of read data is the 603rd sample in the datastore.

Inspect Earlier Sample

Inspect the 403rd sample of loggedfueldata. Due to previous read operations, the datastore now reads starting from the 606th sample, so you must reset the datastore. Then, you can read from the first sample up to the 403rd sample.

Use the重置method to resetDStore.

重置(DStore);

SetReadSizeto200again.

DStore.ReadSize = 200;

Read from the datastore twice to advance the read position to the 401st sample.

read(DStore); read(DStore);

SetReadSizeto5again.

DStore.ReadSize = 5;

Read from the datastore.

read(DStore)

ans = 5x1 timetable Time Data ________ _______ 3.85 sec 0.999 3.86 sec 0.99219 3.87 sec 0.98538 3.88 sec 0.97858 3.89 sec 0.97179

Extract Multiple Samples

Extract samples 1001 through 1020 (a total of 20 samples).

Reset the datastore.

重置(DStore)

一个dvance to sample 1001.

DStore.ReadSize = 200;fori = 1:5 read(DStore);end

Prepare to extract 20 samples from the datastore.

DStore.ReadSize = 20;

Extract samples 1001 through 1020. Store the extracted data in a variable namedtargetSamples.

targetSamples = read(DStore)

targetSamples = 20x1 timetable Time Data ________ ______ 9.7 sec 1.5828 9.71 sec 1.5733 9.72 sec 1.5664 9.73 sec 1.5614 9.74 sec 1.5579 9.75 sec 1.5553 9.76 sec 1.5703 9.77 sec 1.582 9.78 sec 1.5913 9.79 sec 1.5988 9.8 sec 1.605 9.81 sec 1.6101 9.82 sec 1.6145 9.83 sec 1.6184 9.84 sec 1.6049 9.85 sec 1.595 9.86 sec 1.5877 9.87 sec 1.5824 9.88 sec 1.5785 9.89 sec 1.5757

Find Maximum Value of Data in Datastore

Reset the datastore.

重置(DStore)

Write awhileloop, using thehasdatamethod, to incrementally analyze the data in chunks of 200 samples.

DStore.ReadSize = 200; runningMax = [];whilehasdata(DStore) tt = read(DStore); rawChunk = tt.Data; runningMax = max([rawChunk; runningMax]);end

Now, the variablerunningMaxstores the maximum value in the entire datastore.

runningMax

runningMax = 1.6423