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


Most of the standard library in Julia (which can be found in /share/julia/base and /share/julia/stdlib, relative to where Julia was installed) is written in Julia itself. The rest of Julia's code ecosystem is contained in packages that are simply GitHub repositories. They are most often authored by external contributors, and already provide functionality for such diverse disciplines such as bioinformatics, chemistry, cosmology, finance, linguistics, machine learning, mathematics, statistics, and high-performance computing. A package listing can be found at

Julia's installation contains a built-in package manager, Pkg, for installing additional packages that are written in Julia. Version and dependency management is handled automatically by Pkg.

Pkghas a REPL mode, which can be started from within the Julia REPL by entering the ] key, which is often called the REPL's package mode. The Pkg mode is shown as a blue prompt, like this:(v1.0) pkg>.

From this mode, we can start all functions of Pkg. To return to the normal REPL mode, press Backspace or Ctrl C.

To initialize your environment, enter the init command, which creates an empty Project.toml file in your Julia installation folder.

Adding a new package

Before adding a new package, it is always a good idea to update your package database for the already installed packages with the up command. Then, add a new package by issuing the add PackageName command, and execute it by using PackageName in the code or in the REPL.

For example, to add 2D plotting capabilities, install the Plots package with add Plots in the Package mode by first typing ]. This installs the Plots package and all of its dependencies, building them when needed.

To make a graph of 100 random numbers between 0 and 1, execute the following commands:

using Plotsplot(rand(100))

The rand(100) function is an array with 100 random numbers. This produces the following output:

A plot of white noise with Plots

After installing a new Julia version, update all the installed packages by running up in the Pkg REPL-mode.