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Getting Started with Python and Raspberry Pi (Redirected from Learning Python By Developing Raspberry Pi Applications)
Getting Started with Python and Raspberry Pi (Redirected from Learning Python By Developing Raspberry Pi Applications)

Getting Started with Python and Raspberry Pi (Redirected from Learning Python By Developing Raspberry Pi Applications): Learn to design and implement reliable Python applications on the Raspberry Pi using a range of external libraries, the Raspberry Pis GPIO port, and the camera module

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Getting Started with Python and Raspberry Pi (Redirected from Learning Python By Developing Raspberry Pi Applications)

Chapter 2. Understanding Control Flow and Data Types

Now that we are able to run Python code, we will take a look at some of the ways in which we can store data and control the flow of execution through the Python code.

In this chapter, we will cover:

  • The basics of data types in Python
  • Using the math module for operations on numerical types
  • Using the tring module for string manipulation

As mentioned earlier, all the code used in this chapter is written for Python 2.7, and is able to be executed on any Python 2.7 interpreter.

Data in Python

Before jumping to the various data types that are available in Python, it is worth noting that Python is a strong dynamically typed programming language, which means both that:

  • Once a variable (a unit of stored data in a program) has been given a value, its type is set and will not change until the variable is assigned a value of a different type (strong)
  • A variable can hold a value of any type as the type is given by the value, not the variable itself (dynamic)

This is best explained with an example that can be executed from the interactive console, assuming we have a variable representing a string:

flan = "flan"

We can query the value held by the variable and the type using the following code (note that this will only work on an interactive console as return values are automatically printed to the terminal):

flan
type(flan)

As the following output shows, the variable is of type str which represents a string in Python:

Data in Python

We can now reassign the variable to a new numerical...

Control flow operators

If you have ever used any other programming language, you are probably familiar with the standard control flow operators if, for, and while, which are all present in Python and operate in a fairly similar way.

if and while can be used in a similar way as they would usually be with any Boolean expression, as shown in the following example. Since the interactive terminal is not fantastic at handling indentation, we will just run these examples as standard Python scripts.

import random
if random.randint(1, 100) % 2 == 1:
    print "Win!"
else:
    print "Lose!"
times_lost = 0
while random.randint(1, 100) % 2 == 0:
    times_lost += 1
print "Win! (after %d losses)" % (times_lost)

As the following output shows, the execution in the first example is controlled solely by the random number generated in the if statement. In the second, the random number generation determines the amount of times a section of code will be executed whilst the overall...

Using functions

The final topic we will cover in this chapter is that of separating code into functions, and how variables can be passed to and returned from them.

We will first start with a simple function that takes no arguments and does not return a value. The following example shows the basic syntax for a function in Python:

def say_hello():
    print "Hello!"
say_hello()

This example simply prints Hello! to the terminal, as shown in the following output:

Using functions

In the next example, we will introduce an argument which will be used in the string. As the example shows, all that is needed is the argument name unlike the other programming languages, which require a type.

def say_hello(person_name):
    print "Hello, %s!" % (person_name)
say_hello("Sanae")

Tip

If you have a function that only operates on a specific type, you can still enforce arguments to take a specific type using the isinstance() function.

Here the string Hello, Sanae! is printed as shown in the following...

Summary

In this chapter, we looked at the most common data types in Python, took an overview of their operations, and understood how control flow can be controlled within a Python script.

In the next chapter, we will look further into the container data types that can be used to hold multiple pieces of data. We will also take a look at IO and see how our Python programs can interact with the other data and devices on the system.

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Description

The Raspberry Pi is one of the smallest and most affordable single board computers that has taken over the world of hobby electronics and programming, and the Python programming language makes this the perfect platform to start coding with. The book will start with a brief introduction to Raspberry Pi and Python. We will direct you to the official documentation that helps you set up your Raspberry Pi with the necessary equipment such as the monitor, keyboard, mouse, power supply, and so on. It will then dive right into the basics of Python programming. Later, it will focus on other Python tasks, for instance, interfacing with hardware, GUI programming, and more. Once you get well versed with the basic programming, the book will then teach you to develop Python/Raspberry Pi applications. By the end of this book, you will be able to develop Raspberry Pi applications with Python and will have good understanding of Python programming for Raspberry Pi.

Who is this book for?

This book is designed for those who are unfamiliar with the art of Python development and want to get to know their way round the language and the many additional libraries that allow you to get a full application up and running in no time.

What you will learn

  • Fundamentals of Python applications
  • Designing applications for multithreading
  • Interacting with electronics and physical devices
  • Debugging applications when they go wrong
  • Packaging and installing Python modules
  • User interface design using Qt
  • Building easy to use commandline interfaces
  • Connecting applications to the Internet
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Length: 200 pages
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Language : English
ISBN-13 : 9781783551590
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Length: 200 pages
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Language : English
ISBN-13 : 9781783551590
Category :
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Table of Contents

12 Chapters
1. Your First Steps with Python on the Pi Chevron down icon Chevron up icon
2. Understanding Control Flow and Data Types Chevron down icon Chevron up icon
3. Working with Data Structures and I/O Chevron down icon Chevron up icon
4. Understanding Object-oriented Programming and Threading Chevron down icon Chevron up icon
5. Packaging Code with setuptools Chevron down icon Chevron up icon
6. Accessing the GPIO Pins Chevron down icon Chevron up icon
7. Using the Camera Module Chevron down icon Chevron up icon
8. Extracting Data from the Internet Chevron down icon Chevron up icon
9. Creating Command-line Interfaces Chevron down icon Chevron up icon
10. Debugging Applications with PDB and Log Files Chevron down icon Chevron up icon
11. Designing Your GUI with Qt Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Rating distribution
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Felix Dec 11, 2016
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
This is for python 2.7 I was looking for a book on python 3.2
Amazon Verified review Amazon
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