# ClassificationNeuralNetwork

## Description

A `ClassificationNeuralNetwork`

object is a trained, feedforward,
and fully connected neural network for classification. The first fully connected layer of the
neural network has a connection from the network input (predictor data `X`

), and each
subsequent layer has a connection from the previous layer. Each fully connected layer
multiplies the input by a weight matrix (`LayerWeights`

) and
then adds a bias vector (`LayerBiases`

). An
activation function follows each fully connected layer (`Activations`

and
`OutputLayerActivation`

). The final fully connected layer and the subsequent
softmax activation function produce the network's output, namely classification scores
(posterior probabilities) and predicted labels. For more information, see Neural Network Structure.

## Creation

Create a `ClassificationNeuralNetwork`

object by using `fitcnet`

.

## Properties

### Neural Network Properties

`LayerSizes`

— Sizes of fully connected layers

positive integer vector

This property is read-only.

Sizes of the fully connected layers in the neural network model, returned as a
positive integer vector. The *i*th element of
`LayerSizes`

is the number of outputs in the
*i*th fully connected layer of the neural network model.

`LayerSizes`

does not include the size of the final fully
connected layer. This layer always has *K* outputs, where
*K* is the number of classes in `Y`

.

**Data Types: **`single`

| `double`

`LayerWeights`

— Learned layer weights

cell array

This property is read-only.

Learned layer weights for the fully connected layers, returned as a cell array.
The *i*th entry in the cell array corresponds to the layer weights
for the *i*th fully connected layer. For example,
`Mdl.LayerWeights{1}`

returns the weights for the first fully
connected layer of the model `Mdl`

.

`LayerWeights`

includes the weights for the final fully
connected layer.

**Data Types: **`cell`

`LayerBiases`

— Learned layer biases

cell array

This property is read-only.

Learned layer biases for the fully connected layers, returned as a cell array. The
*i*th entry in the cell array corresponds to the layer biases for
the *i*th fully connected layer. For example,
`Mdl.LayerBiases{1}`

returns the biases for the first fully
connected layer of the model `Mdl`

.

`LayerBiases`

includes the biases for the final fully connected
layer.

**Data Types: **`cell`

`Activations`

— Activation functions for fully connected layers

`'relu'`

| `'tanh'`

| `'sigmoid'`

| `'none'`

| cell array of character vectors

This property is read-only.

Activation functions for the fully connected layers of the neural network model, returned as a character vector or cell array of character vectors with values from this table.

Value | Description |
---|---|

`"relu"` | Rectified linear unit (ReLU) function — Performs a threshold operation on each element of the input, where any value less than zero is set to zero, that is, $$f\left(x\right)=\{\begin{array}{cc}x,& x\ge 0\\ 0,& x<0\end{array}$$ |

`"tanh"` | Hyperbolic tangent (tanh) function — Applies the |

`"sigmoid"` | Sigmoid function — Performs the following operation on each input element: $$f(x)=\frac{1}{1+{e}^{-x}}$$ |

`"none"` | Identity function — Returns each input element without performing any transformation, that is, |

If

`Activations`

contains only one activation function, then it is the activation function for every fully connected layer of the neural network model, excluding the final fully connected layer. The activation function for the final fully connected layer is always softmax (`OutputLayerActivation`

).If

`Activations`

is an array of activation functions, then the*i*th element is the activation function for the*i*th layer of the neural network model.

**Data Types: **`char`

| `cell`

`OutputLayerActivation`

— Activation function for final fully connected layer

`'softmax'`

This property is read-only.

Activation function for the final fully connected layer, returned as
`'softmax'`

. The function takes each input
*x _{i}* and returns the following, where

*K*is the number of classes in the response variable:

$$f({x}_{i})=\frac{\mathrm{exp}({x}_{i})}{{\displaystyle \sum _{j=1}^{K}\mathrm{exp}({x}_{j})}}.$$

The results correspond to the predicted classification scores (or posterior probabilities).

`ModelParameters`

— Parameter values used to train model

`NeuralNetworkParams`

object

This property is read-only.

Parameter values used to train the `ClassificationNeuralNetwork`

model, returned as a `NeuralNetworkParams`

object.
`ModelParameters`

contains parameter values such as the
name-value arguments used to train the neural network classifier.

Access the properties of `ModelParameters`

by using dot
notation. For example, access the function used to initialize the fully connected
layer weights of a model `Mdl`

by using
`Mdl.ModelParameters.LayerWeightsInitializer`

.

### Convergence Control Properties

`ConvergenceInfo`

— Convergence information

structure array

This property is read-only.

Convergence information, returned as a structure array.

Field | Description |
---|---|

`Iterations` | Number of training iterations used to train the neural network model |

`TrainingLoss` | Training cross-entropy loss for the returned model, or
`resubLoss(Mdl,'LossFun','crossentropy')` for model
`Mdl` |

`Gradient` | Gradient of the loss function with respect to the weights and biases at the iteration corresponding to the returned model |

`Step` | Step size at the iteration corresponding to the returned model |

`Time` | Total time spent across all iterations (in seconds) |

`ValidationLoss` | Validation cross-entropy loss for the returned model |

`ValidationChecks` | Maximum number of times in a row that the validation loss was greater than or equal to the minimum validation loss |

`ConvergenceCriterion` | Criterion for convergence |

`History` | See `TrainingHistory` |

**Data Types: **`struct`

`TrainingHistory`

— Training history

table

This property is read-only.

Training history, returned as a table.

Column | Description |
---|---|

`Iteration` | Training iteration |

`TrainingLoss` | Training cross-entropy loss for the model at this iteration |

`Gradient` | Gradient of the loss function with respect to the weights and biases at this iteration |

`Step` | Step size at this iteration |

`Time` | Time spent during this iteration (in seconds) |

`ValidationLoss` | Validation cross-entropy loss for the model at this iteration |

`ValidationChecks` | Running total of times that the validation loss is greater than or equal to the minimum validation loss |

**Data Types: **`table`

`Solver`

— Solver used to train neural network model

`'LBFGS'`

This property is read-only.

Solver used to train the neural network model, returned as
`'LBFGS'`

. To create a `ClassificationNeuralNetwork`

model, `fitcnet`

uses a limited-memory
Broyden-Fletcher-Goldfarb-Shanno quasi-Newton algorithm (LBFGS) as its loss function
minimization technique, where the software minimizes the cross-entropy loss.

### Predictor Properties

`PredictorNames`

— Predictor variable names

cell array of character vectors

This property is read-only.

Predictor variable names, returned as a cell array of character vectors. The order
of the elements of `PredictorNames`

corresponds to the order in which
the predictor names appear in the training data.

**Data Types: **`cell`

`CategoricalPredictors`

— Categorical predictor indices

vector of positive integers | `[]`

This property is read-only.

Categorical predictor indices, returned as a
vector of positive integers. Assuming that the predictor data contains observations in
rows, `CategoricalPredictors`

contains index values corresponding to
the columns of the predictor data that contain categorical predictors. If none of the
predictors are categorical, then this property is empty
(`[]`

).

**Data Types: **`double`

`ExpandedPredictorNames`

— Expanded predictor names

cell array of character vectors

This property is read-only.

Expanded predictor names, returned as a cell array of character vectors. If the
model uses encoding for categorical variables, then
`ExpandedPredictorNames`

includes the names that describe the
expanded variables. Otherwise, `ExpandedPredictorNames`

is the same
as `PredictorNames`

.

**Data Types: **`cell`

`Mu`

— Predictor means

numeric vector | `[]`

*Since R2023b*

This property is read-only.

Predictor means, returned as a numeric vector. If you set `Standardize`

to
`1`

or `true`

when
you train the neural network model, then the length of the
`Mu`

vector is equal to the
number of expanded predictors (see
`ExpandedPredictorNames`

). The
vector contains `0`

values for dummy variables
corresponding to expanded categorical predictors.

If you set `Standardize`

to `0`

or `false`

when you train the neural network model, then the `Mu`

value is an empty vector (`[]`

).

**Data Types: **`double`

`Sigma`

— Predictor standard deviations

numeric vector | `[]`

*Since R2023b*

This property is read-only.

Predictor standard deviations, returned as a numeric vector. If you set
`Standardize`

to `1`

or `true`

when you train the neural network model, then the length of the
`Sigma`

vector is equal to the number of expanded predictors (see
`ExpandedPredictorNames`

). The vector contains
`1`

values for dummy variables corresponding to expanded
categorical predictors.

If you set `Standardize`

to `0`

or `false`

when you train the neural network model, then the `Sigma`

value is an empty vector (`[]`

).

**Data Types: **`double`

`X`

— Unstandardized predictors

numeric matrix | table

This property is read-only.

Unstandardized predictors used to train the neural network model, returned as a
numeric matrix or table. `X`

retains its original orientation, with
observations in rows or columns depending on the value of the
`ObservationsIn`

name-value argument in the call to
`fitcnet`

.

**Data Types: **`single`

| `double`

| `table`

### Response Properties

`ClassNames`

— Unique class names

numeric vector | categorical vector | logical vector | character array | cell array of character vectors

This property is read-only.

Unique class names used in training, returned as a numeric vector, categorical
vector, logical vector, character array, or cell array of character vectors.
`ClassNames`

has the same data type as the class labels
`Y`

. (The software
treats string arrays as cell arrays of character vectors.)
`ClassNames`

also determines the class order.

**Data Types: **`single`

| `double`

| `categorical`

| `logical`

| `char`

| `cell`

`ResponseName`

— Response variable name

character vector

This property is read-only.

Response variable name, returned as a character vector.

**Data Types: **`char`

`Y`

— Class labels

numeric vector | categorical vector | logical vector | character array | cell array of character vectors

This property is read-only.

Class labels used to train the model, returned as a numeric vector, categorical
vector, logical vector, character array, or cell array of character vectors.
`Y`

has the same data type as the response variable used to train
the model. (The software treats string arrays
as cell arrays of character vectors.)

Each row of `Y`

represents the classification of the
corresponding observation in `X`

.

**Data Types: **`single`

| `double`

| `categorical`

| `logical`

| `char`

| `cell`

### Other Data Properties

`HyperparameterOptimizationResults`

— Cross-validation optimization of hyperparameters

`BayesianOptimization`

object | table

This property is read-only.

Cross-validation optimization of hyperparameters, specified as a `BayesianOptimization`

object or a table of hyperparameters and associated
values. This property is nonempty if the `'OptimizeHyperparameters'`

name-value pair argument is nonempty when you create the model. The value of
`HyperparameterOptimizationResults`

depends on the setting of the
`Optimizer`

field in the
`HyperparameterOptimizationOptions`

structure when you create the
model.

Value of `Optimizer` Option | Value of `HyperparameterOptimizationResults` |
---|---|

`"bayesopt"` (default) | Object of class `BayesianOptimization` |

`"gridsearch"` or `"randomsearch"` | Table of hyperparameters used, observed objective function values (cross-validation loss), and rank of observations from lowest (best) to highest (worst) |

`NumObservations`

— Number of observations

positive numeric scalar

This property is read-only.

Number of observations in the training data stored in `X`

and
`Y`

, returned as a positive numeric scalar.

**Data Types: **`double`

`RowsUsed`

— Observations of original training data stored

logical vector | `[]`

This property is read-only.

Observations of the original training data stored in the model, returned as a
logical vector. This property is empty if all observations are stored in
`X`

and `Y`

.

**Data Types: **`logical`

`W`

— Observation weights

numeric vector

This property is read-only.

Observation weights used to train the model, returned as an
*n*-by-1 numeric vector. *n* is the number of
observations (`NumObservations`

).

The software normalizes the observation weights specified in the
`Weights`

name-value argument so that the elements of
`W`

within a particular class sum up to the prior probability of
that class.

**Data Types: **`single`

| `double`

### Other Classification Properties

`Cost`

— Misclassification cost

numeric square matrix

Misclassification cost, returned as a numeric square matrix, where
`Cost(i,j)`

is the cost of classifying a point into class
`j`

if its true class is `i`

. The cost matrix
always has this form: `Cost(i,j) = 1`

if `i ~= j`

,
and `Cost(i,j) = 0`

if `i = j`

. The rows correspond
to the true class and the columns correspond to the predicted class. The order of the
rows and columns of `Cost`

corresponds to the order of the classes
in `ClassNames`

.

The software uses the `Cost`

value for prediction, but not
training. You can change the `Cost`

property value of the trained
model by using dot notation.

**Data Types: **`double`

`Prior`

— Prior class probabilities

numeric vector

This property is read-only.

Prior class probabilities, returned as a numeric vector. The order of the elements
of `Prior`

corresponds to the elements of
`ClassNames`

.

**Data Types: **`double`

`ScoreTransform`

— Score transformation

character vector | function handle

Score transformation, specified as a character vector or function handle. `ScoreTransform`

represents a built-in transformation function or a function handle for transforming predicted classification scores.

To change the score transformation function to * function*, for example, use dot notation.

For a built-in function, enter a character vector.

Mdl.ScoreTransform = '

*function*';This table describes the available built-in functions.

Value Description `'doublelogit'`

1/(1 + *e*^{–2x})`'invlogit'`

log( *x*/ (1 –*x*))`'ismax'`

Sets the score for the class with the largest score to 1, and sets the scores for all other classes to 0 `'logit'`

1/(1 + *e*^{–x})`'none'`

or`'identity'`

*x*(no transformation)`'sign'`

–1 for *x*< 0

0 for*x*= 0

1 for*x*> 0`'symmetric'`

2 *x*– 1`'symmetricismax'`

Sets the score for the class with the largest score to 1, and sets the scores for all other classes to –1 `'symmetriclogit'`

2/(1 + *e*^{–x}) – 1For a MATLAB

^{®}function or a function that you define, enter its function handle.Mdl.ScoreTransform = @

*function*;must accept a matrix (the original scores) and return a matrix of the same size (the transformed scores).`function`

**Data Types: **`char`

| `function_handle`

## Object Functions

### Create `CompactClassificationNeuralNetwork`

`compact` | Reduce size of machine learning model |

### Create `ClassificationPartitionedModel`

`crossval` | Cross-validate machine learning model |

### Create `dlnetwork`

`dlnetwork` (Deep Learning Toolbox) | Deep learning neural network |

### Interpret Prediction

`lime` | Local interpretable model-agnostic explanations (LIME) |

`partialDependence` | Compute partial dependence |

`plotPartialDependence` | Create partial dependence plot (PDP) and individual conditional expectation (ICE) plots |

`shapley` | Shapley values |

### Assess Predictive Performance on New Observations

### Assess Predictive Performance on Training Data

`resubEdge` | Resubstitution classification edge |

`resubLoss` | Resubstitution classification loss |

`resubMargin` | Resubstitution classification margin |

`resubPredict` | Classify training data using trained classifier |

### Compare Accuracies

`compareHoldout` | Compare accuracies of two classification models using new data |

`testckfold` | Compare accuracies of two classification models by repeated cross-validation |

### Gather Properties of Classification Neural Network Model

`gather` | Gather properties of Statistics and Machine Learning Toolbox object from GPU |

## Examples

### Train Neural Network Classifier

Train a neural network classifier, and assess the performance of the classifier on a test set.

Read the sample file `CreditRating_Historical.dat`

into a table. The predictor data consists of financial ratios and industry sector information for a list of corporate customers. The response variable consists of credit ratings assigned by a rating agency. Preview the first few rows of the data set.

```
creditrating = readtable("CreditRating_Historical.dat");
head(creditrating)
```

ID WC_TA RE_TA EBIT_TA MVE_BVTD S_TA Industry Rating _____ ______ ______ _______ ________ _____ ________ _______ 62394 0.013 0.104 0.036 0.447 0.142 3 {'BB' } 48608 0.232 0.335 0.062 1.969 0.281 8 {'A' } 42444 0.311 0.367 0.074 1.935 0.366 1 {'A' } 48631 0.194 0.263 0.062 1.017 0.228 4 {'BBB'} 43768 0.121 0.413 0.057 3.647 0.466 12 {'AAA'} 39255 -0.117 -0.799 0.01 0.179 0.082 4 {'CCC'} 62236 0.087 0.158 0.049 0.816 0.324 2 {'BBB'} 39354 0.005 0.181 0.034 2.597 0.388 7 {'AA' }

Because each value in the `ID`

variable is a unique customer ID, that is, `length(unique(creditrating.ID))`

is equal to the number of observations in `creditrating`

, the `ID`

variable is a poor predictor. Remove the `ID`

variable from the table, and convert the `Industry`

variable to a `categorical`

variable.

```
creditrating = removevars(creditrating,"ID");
creditrating.Industry = categorical(creditrating.Industry);
```

Convert the `Rating`

response variable to a `categorical`

variable.

creditrating.Rating = categorical(creditrating.Rating, ... ["AAA","AA","A","BBB","BB","B","CCC"]);

Partition the data into training and test sets. Use approximately 80% of the observations to train a neural network model, and 20% of the observations to test the performance of the trained model on new data. Use `cvpartition`

to partition the data.

rng("default") % For reproducibility of the partition c = cvpartition(creditrating.Rating,"Holdout",0.20); trainingIndices = training(c); % Indices for the training set testIndices = test(c); % Indices for the test set creditTrain = creditrating(trainingIndices,:); creditTest = creditrating(testIndices,:);

Train a neural network classifier by passing the training data `creditTrain`

to the `fitcnet`

function.

`Mdl = fitcnet(creditTrain,"Rating")`

Mdl = ClassificationNeuralNetwork PredictorNames: {'WC_TA' 'RE_TA' 'EBIT_TA' 'MVE_BVTD' 'S_TA' 'Industry'} ResponseName: 'Rating' CategoricalPredictors: 6 ClassNames: [AAA AA A BBB BB B CCC] ScoreTransform: 'none' NumObservations: 3146 LayerSizes: 10 Activations: 'relu' OutputLayerActivation: 'softmax' Solver: 'LBFGS' ConvergenceInfo: [1x1 struct] TrainingHistory: [1000x7 table]

`Mdl`

is a trained `ClassificationNeuralNetwork`

classifier. You can use dot notation to access the properties of `Mdl`

. For example, you can specify `Mdl.TrainingHistory`

to get more information about the training history of the neural network model.

Evaluate the performance of the classifier on the test set by computing the test set classification error. Visualize the results by using a confusion matrix.

testAccuracy = 1 - loss(Mdl,creditTest,"Rating", ... "LossFun","classiferror")

testAccuracy = 0.7977

confusionchart(creditTest.Rating,predict(Mdl,creditTest))

### Specify Neural Network Classifier Architecture

Specify the structure of a neural network classifier, including the size of the fully connected layers.

Load the `ionosphere`

data set, which includes radar signal data. `X`

contains the predictor data, and `Y`

is the response variable, whose values represent either good ("g") or bad ("b") radar signals.

`load ionosphere`

Separate the data into training data (`XTrain`

and `YTrain`

) and test data (`XTest`

and `YTest`

) by using a stratified holdout partition. Reserve approximately 30% of the observations for testing, and use the rest of the observations for training.

rng("default") % For reproducibility of the partition cvp = cvpartition(Y,"Holdout",0.3); XTrain = X(training(cvp),:); YTrain = Y(training(cvp)); XTest = X(test(cvp),:); YTest = Y(test(cvp));

Train a neural network classifier. Specify to have 35 outputs in the first fully connected layer and 20 outputs in the second fully connected layer. By default, both layers use a rectified linear unit (ReLU) activation function. You can change the activation functions for the fully connected layers by using the `Activations`

name-value argument.

Mdl = fitcnet(XTrain,YTrain, ... "LayerSizes",[35 20])

Mdl = ClassificationNeuralNetwork ResponseName: 'Y' CategoricalPredictors: [] ClassNames: {'b' 'g'} ScoreTransform: 'none' NumObservations: 246 LayerSizes: [35 20] Activations: 'relu' OutputLayerActivation: 'softmax' Solver: 'LBFGS' ConvergenceInfo: [1x1 struct] TrainingHistory: [47x7 table]

Access the weights and biases for the fully connected layers of the trained classifier by using the `LayerWeights`

and `LayerBiases`

properties of `Mdl`

. The first two elements of each property correspond to the values for the first two fully connected layers, and the third element corresponds to the values for the final fully connected layer with a softmax activation function for classification. For example, display the weights and biases for the second fully connected layer.

Mdl.LayerWeights{2}

`ans = `*20×35*
0.0481 0.2501 -0.1535 -0.0934 0.0760 -0.0579 -0.2465 1.0411 0.3712 -1.2007 1.1162 0.4296 0.4045 0.5005 0.8839 0.4624 -0.3154 0.3454 -0.0487 0.2648 0.0732 0.5773 0.4286 0.0881 0.9468 0.2981 0.5534 1.0518 -0.0224 0.6894 0.5527 0.7045 -0.6124 0.2145 -0.0790
-0.9489 -1.8343 0.5510 -0.5751 -0.8726 0.8815 0.0203 -1.6379 2.0315 1.7599 -1.4153 -1.4335 -1.1638 -0.1715 1.1439 -0.7661 1.1230 -1.1982 -0.5409 -0.5821 -0.0627 -0.7038 -0.0817 -1.5773 -1.4671 0.2053 -0.7931 -1.6201 -0.1737 -0.7762 -0.3063 -0.8771 1.5134 -0.4611 -0.0649
-0.1910 0.0246 -0.3511 0.0097 0.3160 -0.0693 0.2270 -0.0783 -0.1626 -0.3478 0.2765 0.4179 0.0727 -0.0314 -0.1798 -0.0583 0.1375 -0.1876 0.2518 0.2137 0.1497 0.0395 0.2859 -0.0905 0.4325 -0.2012 0.0388 -0.1441 -0.1431 -0.0249 -0.2200 0.0860 -0.2076 0.0132 0.1737
-0.0415 -0.0059 -0.0753 -0.1477 -0.1621 -0.1762 0.2164 0.1710 -0.0610 -0.1402 0.1452 0.2890 0.2872 -0.2616 -0.4204 -0.2831 -0.1901 0.0036 0.0781 -0.0826 0.1588 -0.2782 0.2510 -0.1069 -0.2692 0.2306 0.2521 0.0306 0.2524 -0.4218 0.2478 0.2343 -0.1031 0.1037 0.1598
1.1848 1.6142 -0.1352 0.5774 0.5491 0.0103 0.0209 0.7219 -0.8643 -0.5578 1.3595 1.5385 1.0015 0.7416 -0.4342 0.2279 0.5667 1.1589 0.7100 0.1823 0.4171 0.7051 0.0794 1.3267 1.2659 0.3197 0.3947 0.3436 -0.1415 0.6607 1.0071 0.7726 -0.2840 0.8801 0.0848
0.2486 -0.2920 -0.0004 0.2806 0.2987 -0.2709 0.1473 -0.2580 -0.0499 -0.0755 0.2000 0.1535 -0.0285 -0.0520 -0.2523 -0.2505 -0.0437 -0.2323 0.2023 0.2061 -0.1365 0.0744 0.0344 -0.2891 0.2341 -0.1556 0.1459 0.2533 -0.0583 0.0243 -0.2949 -0.1530 0.1546 -0.0340 -0.1562
-0.0516 0.0640 0.1824 -0.0675 -0.2065 -0.0052 -0.1682 -0.1520 0.0060 0.0450 0.0813 -0.0234 0.0657 0.3219 -0.1871 0.0658 -0.2103 0.0060 -0.2831 -0.1811 -0.0988 0.2378 -0.0761 0.1714 -0.1596 -0.0011 0.0609 0.4003 0.3687 -0.2879 0.0910 0.0604 -0.2222 -0.2735 -0.1155
-0.6192 -0.7804 -0.0506 -0.4205 -0.2584 -0.2020 -0.0008 0.0534 1.0185 -0.0307 -0.0539 -0.2020 0.0368 -0.1847 0.0886 -0.4086 -0.4648 -0.3785 0.1542 -0.5176 -0.3207 0.1893 -0.0313 -0.5297 -0.1261 -0.2749 -0.6152 -0.5914 -0.3089 0.2432 -0.3955 -0.1711 0.1710 -0.4477 0.0718
0.5049 -0.1362 -0.2218 0.1637 -0.1282 -0.1008 0.1445 0.4527 -0.4887 0.0503 0.1453 0.1316 -0.3311 -0.1081 -0.7699 0.4062 -0.1105 -0.0855 0.0630 -0.1469 -0.2533 0.3976 0.0418 0.5294 0.3982 0.1027 -0.0973 -0.1282 0.2491 0.0425 0.0533 0.1578 -0.8403 -0.0535 -0.0048
1.1109 -0.0466 0.4044 0.6366 0.1863 0.5660 0.2839 0.8793 -0.5497 0.0057 0.3468 0.0980 0.3364 0.4669 0.1466 0.7883 -0.1743 0.4444 0.4535 0.1521 0.7476 0.2246 0.4473 0.2829 0.8881 0.4666 0.6334 0.3105 0.9571 0.2808 0.6483 0.1180 -0.4558 1.2486 0.2453
⋮

Mdl.LayerBiases{2}

`ans = `*20×1*
0.6147
0.1891
-0.2767
-0.2977
1.3655
0.0347
0.1509
-0.4839
-0.3960
0.9248
⋮

The final fully connected layer has two outputs, one for each class in the response variable. The number of layer outputs corresponds to the first dimension of the layer weights and layer biases.

size(Mdl.LayerWeights{end})

`ans = `*1×2*
2 20

size(Mdl.LayerBiases{end})

`ans = `*1×2*
2 1

To estimate the performance of the trained classifier, compute the test set classification error for `Mdl`

.

testError = loss(Mdl,XTest,YTest, ... "LossFun","classiferror")

testError = 0.0774

accuracy = 1 - testError

accuracy = 0.9226

`Mdl`

accurately classifies approximately 92% of the observations in the test set.

## Extended Capabilities

### C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

The

`predict`

object function supports code generation.

For more information, see Introduction to Code Generation.

### GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™. (since R2024b)

Usage notes and limitations:

The following object functions fully support GPU arrays:

The object functions execute on a GPU if at least one of the following applies:

The model was fitted with GPU arrays.

The predictor data that you pass to the object function is a GPU array.

For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

## Version History

**Introduced in R2021a**

### R2024b: Specify GPU arrays (requires Parallel Computing Toolbox)

### R2024b: Convert to `dlnetwork`

Convert a `ClassificationNeuralNetwork`

object to a `dlnetwork`

(Deep Learning Toolbox) object using the `dlnetwork`

function. Use
`dlnetwork`

objects to make further edits and customize the underlying
neural network of a `ClassificationNeuralNetwork`

object and retrain it using the `trainnet`

(Deep Learning Toolbox)
function or a custom training loop.

### R2023b: Model stores observations with missing predictor values

Starting in R2023b, training observations with missing predictor values are included in the `X`

, `Y`

, and `W`

data properties. The `RowsUsed`

property indicates the training observations stored in the model, rather than those used for training. Observations with missing predictor values continue to be omitted from the model training process.

In previous releases, the software omitted training observations that contained missing predictor values from the data properties of the model.

### R2023b: Neural network models include standardization properties

Neural network models include `Mu`

and `Sigma`

properties that contain the means and standard deviations, respectively, used to standardize the predictors before training. The properties are empty when the fitting function does not perform any standardization.

### R2023a: Neural network classifiers support misclassification costs and prior probabilities

`fitcnet`

supports misclassification costs and prior probabilities for
neural network classifiers. Specify the `Cost`

and
`Prior`

name-value arguments when you create a model. Alternatively,
you can specify misclassification costs after training a model by using dot notation to
change the `Cost`

property value of the
model.

Mdl.Cost = [0 2; 1 0];

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