**Steps to building a neural network using keras**

**What are the model phases to build neural network**

## Steps to building a neural network using keras

Keras, a high-level neural networks API, provides a simple and intuitive way to build, train, and deploy deep learning models. Let's break down how the Keras Sequential model, often used for building simple feedforward neural networks, solves a deep learning task step by step:

**Import Libraries**:

The first step is to import the necessary libraries, including TensorFlow (or another backend like Theano or CNTK) and Keras. This is typically done at the beginning of the script or notebook.

```
from tensorflow import keras
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense
```

**Initialize Model**:

Next, we initialize a Sequential model, which allows us to build a linear stack of layers.

```
model = Sequential()
```

**Add Layers**:

We add layers to the model one by one. Each layer represents a different computation, such as a fully connected layer, a convolutional layer, or a recurrent layer.

```
model.add(Dense(units=64, activation='relu', input_shape=(input_dim,)))
model.add(Dense(units=32, activation='relu'))
model.add(Dense(units=output_dim, activation='softmax'))
```

**Configure Model**:

After adding layers, we configure the model by specifying the loss function, optimizer, and evaluation metrics using the compile method.

```
model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
```

**Model Summary**:

We can print a summary of the model's architecture, including the number of parameters in each layer and the total number of trainable parameters.

```
model.summary()
```

**Train Model**:

We train the model on training data using the fit method. This involves providing the input features (X_train) and corresponding labels (Y_train), as well as specifying the batch size, number of epochs, and validation data.

```
model.fit(X_train, Y_train, batch_size=32, epochs=10, validation_data=(X_val, Y_val))
```

**Evaluate Model**:

After training, we can evaluate the model's performance on the test data using the evaluate method. This provides metrics such as loss and accuracy.

```
loss, accuracy = model.evaluate(X_test, Y_test)
print(f'Test Loss: {loss}, Test Accuracy: {accuracy}')
```

**Make Predictions**:

Finally, we can use the trained model to make predictions on new data using the predict method.

```
predictions = model.predict(X_new_data)
```

That's a basic overview of how the Keras Sequential model solves a deep learning task step by step. It provides a simple and intuitive interface for building and training deep learning models, making it accessible to both beginners and experienced practitioners.

## What are the model phases to build neural network

the activation function is a crucial component of each layer and plays a role during the forward pass, which occurs in both the model construction phase and the training phase.

**Model Construction Phase**:

During the model construction phase, when you add layers to the Sequential model, you specify the activation function for each layer using the activation parameter.

```
model.add(Dense(units=64, activation='relu', input_shape=(input_dim,)))
model.add(Dense(units=32, activation='relu'))
model.add(Dense(units=output_dim, activation='softmax'))
```

Here, 'relu' (Rectified Linear Unit) and 'softmax' are activation functions. These activations are defined and set during the construction of the model. They determine how the output of each layer is calculated during the forward pass.

**Training Phase**:

During the training phase, when you call the compile method to configure the model and the fit method to train it, the model internally uses the specified activation functions for forward propagation.

During forward propagation, the input data passes through each layer of the model, and the activations defined in each layer are applied to the input data to produce the output of the layer.

```
model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
model.fit(X_train, Y_train, batch_size=32, epochs=10, validation_data=(X_val, Y_val))
```

The activation functions are utilized in both the model construction phase (to define the layers) and the training phase (during forward propagation) to introduce non-linearity into the model, allowing it to learn complex patterns in the data.

## Top comments (0)