Book Image

Julia Programming Projects

By : Adrian Salceanu
Book Image

Julia Programming Projects

By: Adrian Salceanu

Overview of this book

Julia is a new programming language that offers a unique combination of performance and productivity. Its powerful features, friendly syntax, and speed are attracting a growing number of adopters from Python, R, and Matlab, effectively raising the bar for modern general and scientific computing. After six years in the making, Julia has reached version 1.0. Now is the perfect time to learn it, due to its large-scale adoption across a wide range of domains, including fintech, biotech, education, and AI. Beginning with an introduction to the language, Julia Programming Projects goes on to illustrate how to analyze the Iris dataset using DataFrames. You will explore functions and the type system, methods, and multiple dispatch while building a web scraper and a web app. Next, you'll delve into machine learning, where you'll build a books recommender system. You will also see how to apply unsupervised machine learning to perform clustering on the San Francisco business database. After metaprogramming, the final chapters will discuss dates and time, time series analysis, visualization, and forecasting. We'll close with package development, documenting, testing and benchmarking. By the end of the book, you will have gained the practical knowledge to build real-world applications in Julia.
Table of Contents (19 chapters)
Title Page
Copyright and Credits
About Packt

Constructing dates and times

In order to construct new date/time objects representing the current date or time, Julia provides two helper functions, now and today. Let's look at some examples in the read-eval-print loop (REPL):

julia> using Dates 
julia> d = today() 

julia> typeof(d) 

julia> dt = now() 

julia> dt |> typeof 

julia> t = Dates.Time(now()) 

julia> typeof(t) 

The now function can also accept an additional argument to return the UTC time (without local adjustments for daylight savings):

julia> now(UTC) 

Internally, all the types wrap an Int64 value that can be accessed through the instant field:

julia> dt.instant 
Dates.UTInstant{Millisecond}(63677378014868 milliseconds) 

julia> t.instant 
75147529000000 nanoseconds 

julia> d.instant 
Dates.UTInstant{Day}(737006 days)

The instant property of the objects reflects the precision level of each type...