Book Image

Julia 1.0 Programming - Second Edition

By : Ivo Balbaert
Book Image

Julia 1.0 Programming - Second Edition

By: Ivo Balbaert

Overview of this book

The release of Julia 1.0 is now ready to change the technical world by combining the high productivity and ease of use of Python and R with the lightning-fast speed of C++. Julia 1.0 programming gives you a head start in tackling your numerical and data problems. You will begin by learning how to set up a running Julia platform, before exploring its various built-in types. With the help of practical examples, this book walks you through two important collection types: arrays and matrices. In addition to this, you will be taken through how type conversions and promotions work. In the course of the book, you will be introduced to the homo-iconicity and metaprogramming concepts in Julia. You will understand how Julia provides different ways to interact with an operating system, as well as other languages, and then you'll discover what macros are. Once you have grasped the basics, you’ll study what makes Julia suitable for numerical and scientific computing, and learn about the features provided by Julia. By the end of this book, you will also have learned how to run external programs. This book covers all you need to know about Julia in order to leverage its high speed and efficiency for your applications.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell

An example project – word frequency

A lot of the concepts and techniques that we have seen so far in this book come together in this little project. Its aim is to read a text file, remove all characters that are not used in words, and count the frequency of the words in the remaining text. This can be useful, for example, when counting the word density on a web page, the frequency of DNA sequences, or the number of hits on a website that came from various IP addresses. This can be done in some ten lines of code. For example, when words1.txt contains the sentence to be, or not to be, that is the question!, then this is the output of the program:

Word : frequency be : 2is : 1not : 1or : 1question : 1that : 1the : 1to : 2

Here is the code with comments:

# code in chapter 5\word_frequency.jl: 
# 1- read in text file: 
str = read("words1.txt", String) 
# 2- replace non alphabet characters from text with a space: 
nonalpha = r"(\W\s?)" # define a regular expression 
str = replace(str, nonalpha =...