Writing Machine Learning Model - PyTorch vs. TF-Keras

Dec 9, 2021 · 4 min read · machine learning deep learning programming ·

PyTorch and Keras are both open-source deep learning frameworks, but they have some significant differences. PyTorch is a low-level framework that allows you to define your own computation graphs, while Keras is a high-level framework that provides a pre-defined set of layers and routines for building deep learning models. This means that PyTorch offers more flexibility and customization, while Keras is easier to use and more accessible to beginners.

Choosing Framework - PyTorch vs. TF-Keras

When deciding between PyTorch and TensorFlow (or Keras), it's important to consider the specific goals and requirements of your project. PyTorch is a good choice for research and development, as it allows for high flexibility and customization, and it integrates well with the Python ecosystem. It also provides a more intuitive interface for working with dynamic graphs, which can be useful for working with complex, unstructured data.

On the other hand, TensorFlow (with or without Keras) is a good choice for production, as it provides a more stable and efficient platform for deploying machine learning models. TensorFlow also has a larger community and more comprehensive support for deploying models on different platforms, such as mobile and web. Additionally, TensorFlow provides a range of pre-trained models and tools for working with large-scale datasets, which can be useful for applications that require high performance and scalability.

Different Ways to Write Machine Learning Models Using Tensorflow-Keras API

There are several ways to define a model in the TensorFlow Keras API. Here are some of the most common ways:

Sequential model

This is the most common way to define a model in Keras. A Sequential model is a linear stack of layers, where you can use the add() method to add layers to the model. For example:

1model = tf.keras.models.Sequential()
2model.add(tf.keras.layers.Dense(units=64, activation='relu', input_shape=(32,)))
3model.add(tf.keras.layers.Dense(units=10, activation='softmax'))

Functional API

The Keras functional API is a way to create models that is more flexible than the Sequential model. It allows you to create models that have multiple inputs and outputs, and it also lets you create models that share layers. For example:

1inputs = tf.keras.Input(shape=(32,))
2x = tf.keras.layers.Dense(units=64, activation='relu')(inputs)
3outputs = tf.keras.layers.Dense(units=10, activation='softmax')(x)
4
5model = tf.keras.Model(inputs=inputs, outputs=outputs)

Model subclassing

You can also define a model using the Keras subclassing API, which allows you to define a model by creating a subclass of the Model class and defining the layers in the __init__() method and the forward pass in the call() method. For example:

 1class MyModel(tf.keras.Model):
 2  def __init__(self):
 3    super(MyModel, self).__init__()
 4    self.dense1 = tf.keras.layers.Dense(units=64, activation='relu')
 5    self.dense2 = tf.keras.layers.Dense(units=10, activation='softmax')
 6
 7  def call(self, inputs):
 8    x = self.dense1(inputs)
 9    return self.dense2(x)
10
11model = MyModel()

These are just some of the ways you can define a model in the TensorFlow Keras API. You may also want to check out the official TensorFlow Keras documentation for more information: https://www.tensorflow.org/api_docs/python/tf/keras/Model.

Different Ways to Write Machine Learning Model Using PyTorch

There are several ways to define a model in PyTorch, including:

nn.Module

This is the most common way to define a model in PyTorch. To define a model using nn.Module, you create a class that subclasses nn.Module and define the layers in the __init__() method and the forward pass in the forward() method. Here's an example:

 1class MyModel(nn.Module):
 2  def __init__(self):
 3    super(MyModel, self).__init__()
 4    self.conv1 = nn.Conv2d(in_channels=1, out_channels=32, kernel_size=3)
 5    self.fc1 = nn.Linear(in_features=24 * 24 * 32, out_features=10)
 6
 7  def forward(self, x):
 8    x = self.conv1(x)
 9    x = x.view(-1, 24 * 24 * 32)  # flatten the tensor
10    return self.fc1(x)
11
12model = MyModel()

nn.Sequential

This is a way to define a model by creating a nn.Sequential object and adding layers to it using the add_module() method. For example:

1model = nn.Sequential(
2    nn.Conv2d(in_channels=1, out_channels=32, kernel_size=3),
3    nn.Linear(in_features=24 * 24 * 32, out_features=10)
4)

Functional API

PyTorch also has a functional API that is similar to the Keras functional API. This allows you to define a model using functions like nn.conv2d() and nn.linear(), and then use torch.nn.utils.functinoal.make_model() to create a model from the functions. Here's an example:

1def conv_fn(x):
2  return nn.Conv2d(in_channels=1, out_channels=32, kernel_size=3)(x)
3
4def fc_fn(x):
5  x = x.view(-1, 24 * 24 * 32)  # flatten the tensor
6  return nn.Linear(in_features=24 * 24 * 32, out_features=10)(x)
7
8model = torch.nn.utils.function.make_model(conv_fn, fc_fn)

These are just some of the ways you can define a model in PyTorch. You may also want to check out the official PyTorch documentation for more information: https://pytorch.org/docs/stable/nn.html.

Author: Sadman Kabir Soumik