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

Date adjustments

Period arithmetic is very powerful, but sometimes we need to express more flexible rules that are dependent on other dates. I'm thinking about last day of the next monthnext Tuesday, or the third Monday of each month.

For such cases, the Dates module exposes the adjuster API. For starters, we have the firstdayof* and the lastdayof* family of functions—firstdayofweek, firstdayofmonth, firstdayofquarter, and firstdayofyear; plus lastdayofweek, lastdayofmonth, lastdayofquarter, and lastdayofyear, respectively. They take as input a date/time object and adjust it to the indicated point in time:

julia> firstdayofweek(Date(2019, 1, 31)) 

In 2019, the first day of the week includes January 31 is Monday, 28.

The lastdayof* family of functions works in a similar manner. But useful as they are, they don't provide enough flexibility. Luckily, we're covered. If we need other dates apart from the first or the last day, we have to reach for the tonext and toprev pair of functions...