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

Working with files

To work with files, we need the IOStream type. IOStream is a type with the IO supertype and has the following characteristics:

  • The fields are given by fieldnames(IOStream):
(:handle, :ios, :name, :mark)  
  • The types are given by IOStream.types:
(Ptr{Nothing}, Array{UInt8,1}, AbstractString, Int64)

The file handle is a pointer of the Ptr type, which is a reference to the file object.

Opening and reading a line-oriented file with the example.dat name is very easy:

// code in Chapter 8\io.jl 
fname = "example.dat"
f1 = open(fname) 

fname is a string that contains the path to the file, using the escaping of special characters with \ when necessary. For example, in Windows, when the file is in the test folder on the D: drive, this would become d:\\test\\example.dat. The f1 variable is now an IOStream(<file example.dat>) object.

To read all lines one after another in an array, use data = readlines(f1), which returns 3-element Array{String,1}:

"this is line 1."
"42; 3.14"
"this is...