Читать книгу Algorithms For Dummies - John Paul Mueller, John Mueller Paul, Luca Massaron - Страница 7

Introduction

You need to learn about algorithms for school or work. Yet, all the books you’ve tried on the subject end up being more along the lines of really good sleep-inducing aids rather than texts to teach you something. Assuming that you can get past the arcane symbols obviously written by a demented two-year-old with a penchant for squiggles, you end up having no idea of why you’d even want to know anything about them. Most math texts are boring! However, Algorithms For Dummies, 2nd Edition is different. The first thing you’ll note is that this book has a definite lack of odd symbols (especially of the squiggly sort) floating about. Yes, you see a few (it is a math book, after all), but what you find instead are clear instructions for using algorithms that actually have names and a history behind them and that perform useful tasks. You’ll encounter simple coding techniques to perform amazing tasks that will intrigue your friends. You can certainly make them jealous as you perform feats of math that they can’t begin to understand. You get all this without having to strain your brain, even a little, and you won’t even fall asleep (well, unless you really want to do so). New in this edition of the book are more details about how algorithms work, and you even get to create your own basic math package so that you know how to do it for that next job interview.

About This Book

Algorithms For Dummies, 2nd Edition is the math book that you wanted in college but didn’t get. You discover, for example, that algorithms aren’t new. After all, the Babylonians used algorithms to perform simple tasks as early as 1,600 BC. If the Babylonians could figure this stuff out, certainly you can, too! This book actually has three things that you won’t find in most math books:

 Algorithms that have actual names and a historical basis so that you can remember the algorithm and know why someone took time to create it

 Simple explanations of how the algorithm performs awesome feats of data manipulation, data analysis, or probability prediction

 Code that shows how to use the algorithm without actually dealing with arcane symbols that no one without a math degree can understand

Part of the emphasis of this book is on using the right tools. This book uses Python to perform various tasks. Python has special features that make working with algorithms significantly easier. For example, Python provides access to a huge array of packages that let you do just about anything you can imagine, and more than a few that you can’t. However, unlike many texts that use Python, this one doesn’t bury you in packages. We use a select group of packages that provide great flexibility with a lot of functionality but don’t require you to pay anything. You can go through this entire book without forking over a cent of your hard-earned money.

You also discover some interesting techniques in this book. The most important is that you don’t just see the algorithms used to perform tasks; you also get an explanation of how the algorithms work. Unlike many other books, Algorithms For Dummies, 2nd Edition enables you to fully understand what you’re doing, but without requiring you to have a PhD in math. Every one of the examples shows the expected output and tells you why that output is important. You aren’t left with the feeling that something is missing.

Of course, you might still be worried about the whole programming environment issue, and this book doesn’t leave you in the dark there, either. This book relies on Google Colab to provide a programming environment (although you can use Jupyter Notebook quite easily, too). Because you access Colab through a browser, you can program anywhere and at any time that you have access to a browser, even on your smartphone while at the dentist’s office or possibly while standing on your head watching reruns of your favorite show.

To help you absorb the concepts, this book uses the following conventions:

 Text that you’re meant to type just as it appears in the book is in bold. The exception is when you’re working through a step list: Because each step is bold, the text to type is not bold.

 Words that we want you to type in that are also in italics are used as placeholders, which means that you need to replace them with something that works for you. For example, if you see “Type Your Name and press Enter,” you need to replace Your Name with your actual name.

 We also use italics for terms we define. This means that you don’t have to rely on other sources to provide the definitions you need.

 Web addresses and programming code appear in monofont. If you're reading a digital version of this book on a device connected to the Internet, you can click the live link to visit that website, like this: http://www.dummies.com.

 When you need to click command sequences, you see them separated by a special arrow, like this: File ⇒ New File, which tells you to click File and then New File.

Foolish Assumptions

You might find it difficult to believe that we’ve assumed anything about you — after all, we haven’t even met you yet! Although most assumptions are indeed foolish, we made certain assumptions to provide a starting point for the book.

The first assumption is that you’re familiar with the platform you want to use, because the book doesn’t provide any guidance in this regard. (Chapter 3 does, however, tell you how to access Google Colab from your browser and use it to work with the code examples in the book.) To give you the maximum information about Python with regard to algorithms, this book doesn’t discuss any platform-specific issues. You really do need to know how to install applications, use applications, and generally work with your chosen platform before you begin working with this book.

This book isn’t a math primer. Yes, you see lots of examples of complex math, but the emphasis is on helping you use Python to perform common tasks using algorithms rather than learning math theory. However, you do get explanations of many of the algorithms used in the book so that you can understand how the algorithms work. Chapters 1 and 2 guide you through a what you need to know in order to use this book successfully. Chapter 5 is a special chapter that discusses how to create your own math library, which significantly aids you in understanding how math works with code to create a reusable package. It also looks dandy on your resume to say that you’ve created your own math library.

This book also assumes that you can access items on the Internet. Sprinkled throughout are numerous references to online material that will enhance your learning experience. However, these added sources are useful only if you actually find and use them. You must also have Internet access to use Google Colab.

Icons Used in This Book

As you read this book, you encounter icons in the margins that indicate material of interest (or not, as the case may be). Here’s what the icons mean:

Tips are nice because they help you save time or perform some task without a lot of extra work. The tips in this book are time-saving techniques or pointers to resources that you should try so that you can get the maximum benefit from Python, or in performing algorithm-related or data analysis–related tasks.

We don’t want to sound like angry parents or some kind of maniacs, but you should avoid doing anything that’s marked with a Warning icon. Otherwise, you might find that your application fails to work as expected, you get incorrect answers from seemingly bulletproof algorithms, or (in the worst-case scenario) you lose data.

Whenever you see this icon, think advanced tip or technique. You might find these tidbits of useful information just too boring for words, or they could contain the solution you need to get a program running. Skip these bits of information whenever you like.

If you don’t get anything else out of a particular chapter or section, remember the material marked by this icon. This text usually contains an essential process or a bit of information that you must know to work with Python, or to perform algorithm-related or data analysis–related tasks successfully.

Beyond the Book

This book isn’t the end of your Python or algorithm learning experience — it’s really just the beginning. We provide online content to make this book more flexible and better able to meet your needs. That way, as we receive email from you, we can address questions and tell you how updates to Python, or its associated add-ons affect book content. In fact, you gain access to all these cool additions:

 Cheat sheet: You remember using crib notes in school to make a better mark on a test, don’t you? You do? Well, a cheat sheet is sort of like that. It provides you with some special notes about tasks that you can do with Python, Google Colab, and algorithms that not every other person knows. To find the cheat sheet for this book, go to www.dummies.com and enter Algorithms For Dummies, 2nd Edition Cheat Sheet in the search box. The cheat sheet contains really neat information such as finding the algorithms that you commonly need to perform specific tasks.

 Updates: Sometimes changes happen. For example, we might not have seen an upcoming change when we looked into our crystal ball during the writing of this book. In the past, this possibility simply meant that the book became outdated and less useful, but you can now find updates to the book, if we make any, by going to www.dummies.com and entering Algorithms For Dummies, 2nd Edition in the search box.In addition to these updates, check out the blog posts with answers to reader questions and demonstrations of useful book-related techniques at http://blog.johnmuellerbooks.com/.

 Companion files: Hey! Who really wants to type all the code in the book and reconstruct all those plots manually? Most readers prefer to spend their time actually working with Python, performing tasks using algorithms, and seeing the interesting things they can do, rather than typing. Fortunately for you, the examples used in the book are available for download, so all you need to do is read the book to learn algorithm usage techniques. You can find these files by searching Algorithms For Dummies, 2nd Edition at www.dummies.com and scrolling down the left side of the page that opens. The source code is also at http://www.johnmuellerbooks.com/source-code/, and https://github.com/lmassaron/algo4d_2ed.

Where to Go from Here

It’s time to start your algorithm learning adventure! If you’re completely new to algorithms, you should start with Chapter 1 and progress through the book at a pace that allows you to absorb as much of the material as possible. Make sure to read about Python, because the book uses this language as needed for the examples.

If you’re a novice who’s in an absolute rush to get going with algorithms as quickly as possible, you can skip to Chapter 3 with the understanding that you may find some topics a bit confusing later.

Readers who have some exposure to Python, and have the appropriate language versions installed, can save reading time by moving directly to Chapter 5. You can always go back to earlier chapters as necessary when you have questions. However, you do need to understand how each technique works before moving to the next one. Every technique, coding example, and procedure has important lessons for you, and you could miss vital content if you start skipping too much information.