Antonello Lobianco - Julia Quick Syntax Reference: A Pocket Guide for Data Science Programming

Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the books product page, located at www.apress.com/9781484251898 . For more detailed information, please visit http://www.apress.com/source-code .

This Julia quick syntax reference book covers the main syntax elements of the Julia language as well as some of its more important packages.

The first chapter explains the basic skills needed to set up the software you need to run and develop Julia programs, including managing Julia packages.

Chapterpresents the many predefined types (integers, strings, arrays, etc.) and the methods to work with them. Memory and copy issues are also presented in this chapter, together with an important discussion about the implementation of the various concepts ofmissingness.

After the basic data types have been introduced, Chapterdeals with how to organize them in a sequence of logical statements to compose your program. Control flow, functions, blocks, and scope are all discussed in this chapter.

In Chapter, we extend our discussion to custom typesin Julia, both primitive and composite types can be custom-definedand to their organization in the program, either using inheritance or composition. This chapter will be of particular use to readers accustomed to other object-oriented programs, in order to see how to apply object-oriented concepts in Julia.

Chapterexplains how to retrieve the inputs needed by your program from a given source (the terminal, a text/CSV/Excel/JSON file, or a remote resource) and conversely, to export the outputs of your program.

In Chapter.

Julia is a relatively new language, and while the package ecosystem is developing extremely rapidly (as most packages can be written directly in the Julia language alone), it is highly likely that you will still need libraries for which a direct port to Julia is not yet available. Conversely, your main workflow may be in another, slower, high-level language and you may want to use Julia to implement some performant-critical tasks. Chaptershows how to use C, C++, Python, and R code and their relative libraries in Julia and, conversely, embed Julia code in Python or R programs.

The following chapter (Chapter) gives a few recommendations for writing efficient code, with runtime performances comparable to compiled languages. We also deal here withprogrammers efficiency, discussing profiling and debugging tools and with a short introduction to runtime exceptions.

This completes the discussion of thecoreof the language. Julia, however, has been designed as a thin language where most features are provided by external packages, either shipped with Julia itself (a sort of Julia Standard Library) or provided by third parties.

Therefore, the second part of the book deals with this Julia package ecosystem. Chapterintroduces the main packages for working with numerical data: storage with data structure packages like DataFrames and IndexedTables ; munging with DataFramesMeta , Query , and Pipe ; and visualization with the Plot package.

If Chapterconcludes the book with a series of tools that are of more general use, like composing dynamic documents with Wave , dealing with ZIP files with ZipFile , and exposing a given Julia model on the web with Interact and Mux . Examples given in the text are intentionally trivial. They are minimal working examples of the syntax for the concepts they explain. If you are looking for recipes directly applicable to your domain, a cookbook kind of book may be more convenient.

While each package has been tested specifically with Julia 1.2 and 1.3-rc4, thanks to the Julia developers commitment to a stable API, they should remain relevant for the entire 1.x series. Concerning third-party packages, we report the exact version we tested our code with. The section entitled Using the Package Manager in Chapterexplains how to update a package to a given version if subsequent versions of the package break the API.

Is such cases, please report the problem to us using the form at https://julia-book.com . We will regularly publish updates and errata on this site, where a discussion forum focused on the book is also available.

This work has been supported by the French National Research Agency through the Laboratory of Excellence, ARBRE, part of the Investissements dAvenir program (ANR 11 LABX-0002-01).

I want to thank Germn Gonzlez-Morris for his valuable help in finding errors in the code and improving the description of the language. I want to also thank Mark Powers, the Apress coordinating editor, for his numerous check ins that pushed me to continue and finish the book.

This has been possible thanks to the understanding and support of my family.