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Train Network with Numeric Features

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This example shows how to create and train a simple neural network for deep learning feature data classification.

If you have a data set of numeric features (for example a collection of numeric data without spatial or time dimensions), then you can train a deep learning network using a feature input layer. For an example showing how to train a network for image classification, see Create Simple Deep Learning Neural Network for Classification.

This example shows how to train a network to classify the gear tooth condition of a transmission system given a mixture of numeric sensor readings, statistics, and categorical labels.

Load Data

Load the transmission casing dataset for training. The data set consists of 208 synthetic readings of a transmission system consisting of 18 numeric readings and three categorical labels:

  1. SigMean — Vibration signal mean

  2. SigMedian — Vibration signal median

  3. SigRMS — Vibration signal RMS

  4. SigVar — Vibration signal variance

  5. SigPeak — Vibration signal peak

  6. SigPeak2Peak — Vibration signal peak to peak

  7. SigSkewness — Vibration signal skewness

  8. SigKurtosis — Vibration signal kurtosis

  9. SigCrestFactor — Vibration signal crest factor

  10. SigMAD — Vibration signal MAD

  11. SigRangeCumSum — Vibration signal range cumulative sum

  12. SigCorrDimension — Vibration signal correlation dimension

  13. SigApproxEntropy — Vibration signal approximate entropy

  14. SigLyapExponent — Vibration signal Lyap exponent

  15. PeakFreq — Peak frequency.

  16. HighFreqPower — High frequency power

  17. EnvPower — Environment power

  18. PeakSpecKurtosis — Peak frequency of spectral kurtosis

  19. SensorCondition — Condition of sensor, specified as "Sensor Drift" or "No Sensor Drift"

  20. ShaftCondition — Condition of shaft, specified as "Shaft Wear" or "No Shaft Wear"

  21. GearToothCondition — Condition of gear teeth, specified as "Tooth Fault" or "No Tooth Fault"

Read the transmission casing data from the CSV file "transmissionCasingData.csv". 

filename = "transmissionCasingData.csv";
tbl = readtable(filename,TextType="String");

Convert the labels for prediction to categorical using the convertvars function.

labelName = "GearToothCondition";
tbl = convertvars(tbl,labelName,"categorical");

View the first few rows of the table.

head(tbl)
    SigMean     SigMedian    SigRMS    SigVar     SigPeak    SigPeak2Peak    SigSkewness    SigKurtosis    SigCrestFactor    SigMAD     SigRangeCumSum    SigCorrDimension    SigApproxEntropy    SigLyapExponent    PeakFreq    HighFreqPower    EnvPower    PeakSpecKurtosis    SensorCondition    ShaftCondition     GearToothCondition
    ________    _________    ______    _______    _______    ____________    ___________    ___________    ______________    _______    ______________    ________________    ________________    _______________    ________    _____________    ________    ________________    _______________    _______________    __________________

    -0.94876     -0.9722     1.3726    0.98387    0.81571       3.6314        -0.041525       2.2666           2.0514         0.8081        28562              1.1429             0.031581            79.931            0          6.75e-06       3.23e-07         162.13         "Sensor Drift"     "No Shaft Wear"      No Tooth Fault  
    -0.97537    -0.98958     1.3937    0.99105    0.81571       3.6314        -0.023777       2.2598           2.0203        0.81017        29418              1.1362             0.037835            70.325            0          5.08e-08       9.16e-08         226.12         "Sensor Drift"     "No Shaft Wear"      No Tooth Fault  
      1.0502      1.0267     1.4449    0.98491     2.8157       3.6314         -0.04162       2.2658           1.9487        0.80853        31710              1.1479             0.031565            125.19            0          6.74e-06       2.85e-07         162.13         "Sensor Drift"     "Shaft Wear"         No Tooth Fault  
      1.0227      1.0045     1.4288    0.99553     2.8157       3.6314        -0.016356       2.2483           1.9707        0.81324        30984              1.1472             0.032088             112.5            0          4.99e-06        2.4e-07         162.13         "Sensor Drift"     "Shaft Wear"         No Tooth Fault  
      1.0123      1.0024     1.4202    0.99233     2.8157       3.6314        -0.014701       2.2542           1.9826        0.81156        30661              1.1469              0.03287            108.86            0          3.62e-06       2.28e-07         230.39         "Sensor Drift"     "Shaft Wear"         No Tooth Fault  
      1.0275      1.0102     1.4338     1.0001     2.8157       3.6314         -0.02659       2.2439           1.9638        0.81589        31102              1.0985             0.033427            64.576            0          2.55e-06       1.65e-07         230.39         "Sensor Drift"     "Shaft Wear"         No Tooth Fault  
      1.0464      1.0275     1.4477     1.0011     2.8157       3.6314        -0.042849       2.2455           1.9449        0.81595        31665              1.1417             0.034159            98.838            0          1.73e-06       1.55e-07         230.39         "Sensor Drift"     "Shaft Wear"         No Tooth Fault  
      1.0459      1.0257     1.4402    0.98047     2.8157       3.6314        -0.035405       2.2757            1.955        0.80583        31554              1.1345               0.0353            44.223            0          1.11e-06       1.39e-07         230.39         "Sensor Drift"     "Shaft Wear"         No Tooth Fault

To train a network using categorical features, you must first convert the categorical features to numeric. First, convert the categorical predictors to categorical using the convertvars function by specifying a string array containing the names of all the categorical input variables. In this data set, there are two categorical features with names "SensorCondition" and "ShaftCondition".

categoricalInputNames = ["SensorCondition" "ShaftCondition"];
tbl = convertvars(tbl,categoricalInputNames,"categorical");

Loop over the categorical input variables. For each variable:

  • Convert the categorical values to one-hot encoded vectors using the onehotencode function.

  • Add the one-hot vectors to the table using the addvars function. Specify to insert the vectors after the column containing the corresponding categorical data.

  • Remove the corresponding column containing the categorical data.

for i = 1:numel(categoricalInputNames)
    name = categoricalInputNames(i);
    oh = onehotencode(tbl(:,name));
    tbl = addvars(tbl,oh,After=name);
    tbl(:,name) = [];
end

Split the vectors into separate columns using the splitvars function.

tbl = splitvars(tbl);

View the first few rows of the table. Notice that the categorical predictors have been split into multiple columns with the categorical values as the variable names.

head(tbl)
    SigMean     SigMedian    SigRMS    SigVar     SigPeak    SigPeak2Peak    SigSkewness    SigKurtosis    SigCrestFactor    SigMAD     SigRangeCumSum    SigCorrDimension    SigApproxEntropy    SigLyapExponent    PeakFreq    HighFreqPower    EnvPower    PeakSpecKurtosis    No Sensor Drift    Sensor Drift    No Shaft Wear    Shaft Wear    GearToothCondition
    ________    _________    ______    _______    _______    ____________    ___________    ___________    ______________    _______    ______________    ________________    ________________    _______________    ________    _____________    ________    ________________    _______________    ____________    _____________    __________    __________________

    -0.94876     -0.9722     1.3726    0.98387    0.81571       3.6314        -0.041525       2.2666           2.0514         0.8081        28562              1.1429             0.031581            79.931            0          6.75e-06       3.23e-07         162.13                0                1                1              0           No Tooth Fault  
    -0.97537    -0.98958     1.3937    0.99105    0.81571       3.6314        -0.023777       2.2598           2.0203        0.81017        29418              1.1362             0.037835            70.325            0          5.08e-08       9.16e-08         226.12                0                1                1              0           No Tooth Fault  
      1.0502      1.0267     1.4449    0.98491     2.8157       3.6314         -0.04162       2.2658           1.9487        0.80853        31710              1.1479             0.031565            125.19            0          6.74e-06       2.85e-07         162.13                0                1                0              1           No Tooth Fault  
      1.0227      1.0045     1.4288    0.99553     2.8157       3.6314        -0.016356       2.2483           1.9707        0.81324        30984              1.1472             0.032088             112.5            0          4.99e-06        2.4e-07         162.13                0                1                0              1           No Tooth Fault  
      1.0123      1.0024     1.4202    0.99233     2.8157       3.6314        -0.014701       2.2542           1.9826        0.81156        30661              1.1469              0.03287            108.86            0          3.62e-06       2.28e-07         230.39                0                1                0              1           No Tooth Fault  
      1.0275      1.0102     1.4338     1.0001     2.8157       3.6314         -0.02659       2.2439           1.9638        0.81589        31102              1.0985             0.033427            64.576            0          2.55e-06       1.65e-07         230.39                0                1                0              1           No Tooth Fault  
      1.0464      1.0275     1.4477     1.0011     2.8157       3.6314        -0.042849       2.2455           1.9449        0.81595        31665              1.1417             0.034159            98.838            0          1.73e-06       1.55e-07         230.39                0                1                0              1           No Tooth Fault  
      1.0459      1.0257     1.4402    0.98047     2.8157       3.6314        -0.035405       2.2757            1.955        0.80583        31554              1.1345               0.0353            44.223            0          1.11e-06       1.39e-07         230.39                0                1                0              1           No Tooth Fault

View the class names of the data set.

classNames = categories(tbl{:,labelName})
classNames = 2x1 cell
    {'No Tooth Fault'}
    {'Tooth Fault'   }

Split Data Set into Training and Validation Sets

Partition the data set into training, validation, and test partitions. Set aside 15% of the data for validation, and 15% for testing.

View the number of observations in the dataset.

numObservations = size(tbl,1)
numObservations = 
208

Determine the number of observations for each partition.

numObservationsTrain = floor(0.7*numObservations)
numObservationsTrain = 
145

numObservationsValidation = floor(0.15*numObservations)
numObservationsValidation = 
31

numObservationsTest = numObservations - numObservationsTrain - numObservationsValidation
numObservationsTest = 
32

Create an array of random indices corresponding to the observations and partition it using the partition sizes.

idx = randperm(numObservations);
idxTrain = idx(1:numObservationsTrain);
idxValidation = idx(numObservationsTrain+1:numObservationsTrain+numObservationsValidation);
idxTest = idx(numObservationsTrain+numObservationsValidation+1:end);

Partition the table of data into training, validation, and testing partitions using the indices.

tblTrain = tbl(idxTrain,:);
tblValidation = tbl(idxValidation,:);
tblTest = tbl(idxTest,:);

Define Network Architecture

Define the network for classification.

Define a network with a feature input layer and specify the number of features. Also, configure the input layer to normalize the data using Z-score normalization. Next, include a fully connected layer with output size 50 followed by a batch normalization layer and a ReLU layer. For classification, specify another fully connected layer with output size corresponding to the number of classes, followed by a softmax layer.

numFeatures = size(tbl,2) - 1;
numClasses = numel(classNames);
 
layers = [
    featureInputLayer(numFeatures,Normalization="zscore")
    fullyConnectedLayer(50)
    batchNormalizationLayer
    reluLayer
    fullyConnectedLayer(numClasses)
    softmaxLayer];

Specify Training Options

Specify the training options.

  • Train the network using Adam.

  • Train using mini-batches of size 16.

  • Shuffle the data every epoch.

  • Monitor the network accuracy during training by specifying validation data.

  • Display the training progress in a plot and suppress the verbose command window output.

The software trains the network on the training data and calculates the accuracy on the validation data at regular intervals during training. The validation data is not used to update the network weights. 

miniBatchSize = 16;

options = trainingOptions("adam", ...
    MiniBatchSize=miniBatchSize, ...
    Shuffle="every-epoch", ...
    ValidationData=tblValidation, ...
    Plots="training-progress", ...
    Metrics="accuracy", ...
    Verbose=false);

Train Network

Train the network using the architecture defined by layers, the training data, and the training options. By default, trainnet uses a GPU if one is available, otherwise, it uses a CPU. Training on a GPU requires Parallel Computing Toolbox™ and a supported GPU device. For information on supported devices, see GPU Computing Requirements (Parallel Computing Toolbox). You can also specify the execution environment by using the ExecutionEnvironment name-value argument of trainingOptions.

The training progress plot shows the mini-batch loss and accuracy and the validation loss and accuracy. For more information on the training progress plot, see Monitor Deep Learning Training Progress.

net = trainnet(tblTrain,layers,"crossentropy",options);

Test Network

Predict the labels of the test data using the trained network and calculate the accuracy. Specify the same mini-batch size used for training.

scores = minibatchpredict(net,tblTest(:,1:end-1),MiniBatchSize=miniBatchSize);
YPred = scores2label(scores,classNames);

Calculate the classification accuracy. The accuracy is the proportion of the labels that the network predicts correctly. 

YTest = tblTest{:,labelName};
accuracy = sum(YPred == YTest)/numel(YTest)
accuracy = 
0.9375

View the results in a confusion matrix.

figure
confusionchart(YTest,YPred)

Figure contains an object of type ConfusionMatrixChart.

See Also

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