# Getting Started with TensorFlow 2.x

Google's TensorFlow engine has a unique way of solving problems, allowing us to solve machine learning problems very efficiently. Nowadays, machine learning is used in almost all areas of life and work, with famous applications in computer vision, speech recognition, language translations, healthcare, and many more. We will cover the basic steps to understand how TensorFlow operates and eventually build up to production code techniques later in the pages of this book. For the moment, the fundamentals presented in this chapter are paramount in order to provide you with a core understanding for the recipes found in the rest of this book.

In this chapter, we'll start by covering some basic recipes and helping you to understand how TensorFlow 2.x works. You'll also learn how to access the data used to run the examples in this book, and how to get additional resources. By the end of this chapter, you should have knowledge of the following...

# How TensorFlow works

Started as an internal project by researchers and engineers from the Google Brain team, initially named **DistBelief**, an open source framework for high performance numerical computations was released in November 2015 under the name TensorFlow (tensors are a generalization of scalars, vectors, matrices, and higher dimensionality matrices). You can read the original paper on the project here: http://download.tensorflow.org/paper/whitepaper2015.pdf. After the appearance of version 1.0 in 2017, last year, Google released TensorFlow 2.0, which continues the development and improvement of TensorFlow by making it more user-friendly and accessible.

Production-oriented and capable of handling different computational architectures (CPUs, GPUs, and now TPUs), TensorFlow is a framework for any kind of computation that requires high performance and easy distribution. It excels at deep learning, making it possible to create everything from shallow networks (neural networks...

# Declaring variables and tensors

Tensors are the primary data structure that TensorFlow uses to operate on the computational graph. Even if now, in TensorFlow 2.x, this aspect is hidden, the data flow graph is still operating behind the scenes. This means that the logic of building a neural network doesn't change all that much between TensorFlow 1.x and TensorFlow 2.x. The most eye-catching aspect is that you no longer have to deal with placeholders, the previous entry gates for data in a TensorFlow 1.x graph.

Now, you simply declare tensors as variables and proceed to building your graph.

A *tensor* is a mathematical term that refers to generalized vectors or matrices. If vectors are one-dimensional and matrices are two-dimensional, a tensor is *n*-dimensional (where *n* could be 1, 2, or even larger).

We can declare these tensors as variables and use them for our computations. To do this, first, we must learn how to create tensors.

## Getting ready

When...

# Using eager execution

When developing deep and complex neural networks, you need to continuously experiment with architectures and data. This proved difficult in TensorFlow 1.0 because you always need to run your code from the beginning to end in order to check whether it worked. TensorFlow 2.x works in eager execution mode as default, which means that you develop and check your code step by step as you progress into your project. This is great news; now we just have to understand how to experiment with eager execution, so we can use this TensorFlow 2.x feature to our advantage. This recipe will provide you with the basics to get started.

## Getting ready

TensorFlow 1.x performed optimally because it executed its computations after compiling a static computational graph. All computations were distributed and connected into a graph as you compiled your network and that graph helped TensorFlow to execute computations, leveraging the available resources (multi-core CPUs of multiple...

# Working with matrices

Understanding how TensorFlow works with matrices is very important when developing the flow of data through computational graphs. In this recipe, we will cover the creation of matrices and the basic operations that can be performed on them with TensorFlow.

It is worth emphasizing the importance of matrices in machine learning (and mathematics in general): machine learning algorithms are computationally expressed as matrix operations. Knowing how to perform matrix computations is a plus when working with TensorFlow, though you may not need it often; its high-end module, Keras, can deal with most of the matrix algebra stuff behind the scenes (more on Keras in *Chapter 3,** Keras*).

This book does not cover the mathematical background on matrix properties and matrix algebra (linear algebra), so the unfamiliar reader is strongly encouraged to learn enough about matrices to be comfortable with matrix algebra. In the *See also* section, you can find a couple of resources...

# Declaring operations

Apart from matrix operations, there are hosts of other TensorFlow operations we must at least be aware of. This recipe will provide you with a quick and essential glance at what you really need to know.

## Getting ready

Besides the standard arithmetic operations, TensorFlow provides us with more operations that we should be aware of. We should acknowledge them and learn how to use them before proceeding. Again, we just import TensorFlow:

```
import tensorflow as tf
```

Now we're ready to run the code to be found in the following section.

## How to do it…

TensorFlow has the standard operations on tensors, that is, `add()`

, `subtract()`

, `multiply()`

, and `division()`

in its `math`

module. Note that all of the operations in this section will evaluate the inputs elementwise, unless specified otherwise:

- TensorFlow provides some variations of
`division()`

and the relevant functions. - It is worth mentioning that
`division()`

returns the same...

# Implementing activation functions

Activation functions are the key for neural networks to approximate non-linear outputs and adapt to non-linear features. They introduce non-linear operations into neural networks. If we're careful as to which activation functions are selected and where we put them, they're very powerful operations that we can tell TensorFlow to fit and optimize.

## Getting ready

When we start to use neural networks, we'll use activation functions regularly because activation functions are an essential part of any neural network. The goal of an activation function is just to adjust weight and bias. In TensorFlow, activation functions are non-linear operations that act on tensors. They are functions that operate in a similar way to the previous mathematical operations. Activation functions serve many purposes, but the main concept is that they introduce a non-linearity into the graph while normalizing the outputs.

## How to do it…

The...

# Working with data sources

For most of this book, we will rely on the use of datasets to fit machine learning algorithms. This section has instructions on how to access each of these datasets through TensorFlow and Python.

Some of the data sources rely on the maintenance of outside websites so that you can access the data. If these websites change or remove this data, then some of the following code in this section may need to be updated. You can find the updated code on this book's GitHub page:

https://github.com/PacktPublishing/Machine-Learning-Using-TensorFlow-Cookbook

## Getting ready

Throughout the book, the majority of the datasets that we will be using are accessible using TensorFlow Datasets, whereas some others will require some extra effort by using a Python script to download, or by manually downloading them through the internet.

**TensorFlow Datasets** (**TFDS**) is a collection of datasets ready to use (you can find the complete list here: https...

# Additional resources

In this section, you will find additional links, documentation sources, and tutorials that will be of great assistance when learning and using TensorFlow.

## Getting ready

When learning how to use TensorFlow, it helps to know where to turn for assistance or pointers. This section lists some resources to get TensorFlow running and to troubleshoot problems.

## How to do it…

Here is a list of TensorFlow resources:

- The code for this book is available online at the Packt repository: https://github.com/PacktPublishing/Machine-Learning-Using-TensorFlow-Cookbook
- The official TensorFlow Python API documentation is located at https://www.tensorflow.org/api_docs/python. Here, there is documentation and examples of all of the functions, objects, and methods in TensorFlow.
- TensorFlow's official tutorials are very thorough and detailed. They are located at https://www.tensorflow.org/tutorials/index.html. They start covering image...