Lobianco Julia Quick Syntax Reference

A Pocket Guide for Data Science Programming
1. Auflage 2019
ISBN: 978-1-4842-5190-4
Verlag: Apress
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 216 Seiten

Reihe: Apress Access Books

This quick Julia programming language guide is a condensed code and syntax reference to the Julia 1.x programming language, updated with the latest features of the Julia APIs, libraries, and packages. It presents the essential Julia syntax in a well-organized format that can be used as a handy reference. 

This book provides an introduction that reveals basic Julia structures and syntax; discusses data types, control flow, functions, input/output, exceptions, metaprogramming, performance, and more.  Additionally, you'll learn to interface Julia with other programming languages such as R for statistics or Python. You will learn how to use Julia packages for data analysis, numerical optimization and symbolic computation, and how to disseminate your results in dynamic documents or interactive web pages.  

In this book, the focus is on providing important information as quickly as possible. It is packed with useful information and is a must-have for any Julia programmer.

What You Will Learn  

• Set up the software needed to run Julia and your first Hello World example
• Work with types and the different containers that Julia makes available for rapid application development
• Use vectorized, classical loop-based code, logical operators, and blocks
• Explore Julia functions by looking at arguments, return values, polymorphism, parameters, anonymous functions, and broadcasts
• Build custom structures in Julia
• Interface Julia with other languages such as C/C++, Python, and R
• Program a richer API, modifying the code before it is executed using expressions, symbols, macros, quote blocks, and more
• Maximize your code’s performance 

Who This Book Is For

Experienced programmers new to Julia, as well as existing Julia coders new tothe now stable Julia version 1.0 release.

Autoren/Hrsg.

Lobianco, Antonello

Inhaltsverzeichnis

1;Table of Contents;4
2;About the Author;10
3;About the Technical Reviewer;11
4;Acknowledgments;12
5;Introduction;13
6;Part I: Language Core;16
6.1;Chapter 1: Getting Started;17
6.1.1;1.1 Why Julia?;17
6.1.2;1.2 Installing Julia;19
6.1.3;1.3 Running Julia;22
6.1.4;1.4 Miscellaneous Syntax Elements;24
6.1.5;1.5 Packages;25
6.1.5.1;1.5.1 Using the Package Manager;26
6.1.5.2;1.5.2 Using Packages;27
6.1.6;1.6 Help System;29
6.2;Chapter 2: Data Types and Structures;31
6.2.1;2.1 Simple Types (Non-Containers);32
6.2.1.1;2.1.1 Basic Mathematic Operations;33
6.2.1.2;2.1.2 Strings;33
6.2.1.2.1;Concatenation;34
6.2.2;2.2 Arrays (Lists);35
6.2.2.1;2.2.1 Multidimensional and Nested Arrays;39
6.2.3;2.3 Tuples;44
6.2.4;2.4 Named Tuples;45
6.2.5;2.5 Dictionaries;46
6.2.6;2.6 Sets;48
6.2.7;2.7 Memory and Copy Issues;48
6.2.8;2.8 Various Notes on Data Types;52
6.2.8.1;2.8.1 Random Numbers;53
6.2.8.2;2.8.2 Missing, Nothing, and NaN;53
6.3;Chapter 3: Control Flow and Functions;55
6.3.1;3.1 Code Block Structure and Variable Scope;55
6.3.2;3.2 Repeated Iteration: for and while Loops, List Comprehension, Maps;57
6.3.3;3.3 Conditional Statements: if Blocks, Ternary Operator;58
6.3.4;3.4 Functions;59
6.3.4.1;3.4.1 Arguments;61
6.3.4.2;3.4.2 Return Value;63
6.3.4.3;3.4.3 Multiple-Dispatch (aka Polymorphism);63
6.3.4.4;3.4.4 Templates (Type Parameterization);64
6.3.4.5;3.4.5 Functions as Objects;65
6.3.4.6;3.4.6 Call by Reference/Call by Value;65
6.3.4.7;3.4.7 Anonymous Functions (aka “Lambda” Functions);66
6.3.4.8;3.4.8 Broadcasting Functions;67
6.3.5;3.5 Do Blocks;68
6.3.6;3.6 Exiting Julia;68
6.4;Chapter 4: Custom Types;70
6.4.1;4.1 Primitive Type Definition;71
6.4.2;4.2 Structure Definition;72
6.4.3;4.3 Object Initialization and Usage;73
6.4.4;4.4 Abstract Types and Inheritance;74
6.4.4.1;4.4.1 Implementation of the Object-Oriented Paradigm in Julia;76
6.4.5;4.5 Some Useful Functions Related to Types;79
6.5;Chapter 5: Input/Output;80
6.5.1;5.1 Reading (Input);81
6.5.1.1;5.1.1 Reading from the Terminal;81
6.5.1.2;5.1.2 Reading from a File;82
6.5.1.2.1;Importing Data for a Matrix;83
6.5.1.2.2;Parsing Comma Separated Value (CSV) Files;83
6.5.1.3;5.1.3 Importing Data from Excel;84
6.5.1.4;5.1.4 Importing Data from JSON;85
6.5.1.5;5.1.5 Accessing Web Resources (HTTP);87
6.5.2;5.2 Writing (Output);88
6.5.2.1;5.2.1 Writing to the Terminal;88
6.5.2.2;5.2.2 Writing to a File;89
6.5.2.3;5.2.3 Exporting to CSV;90
6.5.2.4;5.2.4 Exporting Data to Excel;91
6.5.2.5;5.2.5 Exporting Data to JSON;92
6.5.3;5.3 Other Specialized IO;93
6.6;Chapter 6: Metaprogramming and Macros;94
6.6.1;6.1 Symbols;95
6.6.2;6.2 Expressions;96
6.6.2.1;6.2.1 Creating Expressions;97
6.6.2.1.1;Parse a String;97
6.6.2.1.2;Colon Prefix Operator;97
6.6.2.1.3;Quote Block;97
6.6.2.1.4;Use the Exp Constructor with a Tree;98
6.6.2.2;6.2.2 Evaluating Symbols and Expressions;98
6.6.3;6.3 Macros;100
6.6.3.1;6.3.1 Macro Definition;100
6.6.3.2;6.3.2 Macro Invocation;101
6.6.3.3;6.3.3 String Macros;102
6.7;Chapter 7: Interfacing Julia with Other Languages;104
6.7.1;7.1 Julia ? C;105
6.7.2;7.2 Julia ? C++;107
6.7.2.1;7.2.1 Interactive C++ Prompt;107
6.7.2.2;7.2.2 Embed C++ Code in a Julia Program;108
6.7.2.3;7.2.3 Load a C++ Library;111
6.7.3;7.3 Julia ? Python;113
6.7.3.1;7.3.1 Embed Python Code in a Julia Program;114
6.7.3.2;7.3.2 Use Python Libraries;115
6.7.3.3;7.3.3 PyJulia: Using Julia in Python;116
6.7.3.3.1;Installation;116
6.7.3.3.2;Usage;117
6.7.4;7.4 Julia ? R;119
6.7.4.1;7.4.1 Interactive R Prompt;120
6.7.4.2;7.4.2 Embed R Code in a Julia Program;120
6.7.4.3;7.4.3 Use R Libraries;121
6.7.4.4;7.4.4 JuliaCall: Using Julia in R;122
6.7.4.4.1;Installation;122
6.7.4.4.2;Usage;122
6.8;Chapter 8: Effectively Write Efficient Code;125
6.8.1;8.1 Performance;126
6.8.1.1;8.1.1 Benchmarking;126
6.8.1.2;8.1.2 Profiling;128
6.8.1.3;8.1.3 Type Stability;132
6.8.1.4;8.1.4 Other Tips to Improve Performance;134
6.8.1.4.1;Avoid Using Global Variables and Run Performance-Critical Code Within Functions;134
6.8.1.4.2;Annotate the Type of Data Structures;134
6.8.1.4.3;Annotate the Fields of Composite Types;134
6.8.1.4.4;Loop Matrix Elements by Column and Then by Row;135
6.8.2;8.2 Code Parallelization;136
6.8.2.1;8.2.1 Adding and Removing Processes;136
6.8.2.2;8.2.2 Running Heavy Computations on a List of Items;138
6.8.2.3;8.2.3 Aggregate Results;139
6.8.3;8.3 Debugging;140
6.8.3.1;8.3.1 Introspection Tools;141
6.8.3.2;8.3.2 Debugging Tools;142
6.8.4;8.4 Managing Runtime Errors (Exceptions);145
7;Part II: Packages Ecosystem;146
7.1;Chapter 9: Working with Data;147
7.1.1;9.1 Using the DataFrames Package;148
7.1.1.1;9.1.1 Installing and Importing the Library;148
7.1.1.2;9.1.2 Creating a DataFrame or Loading Data;149
7.1.1.3;9.1.3 Getting Insights About the Data;151
7.1.1.4;9.1.4 Filtering Data (Selecting or Querying Data);152
7.1.1.5;9.1.5 Editing Data;155
7.1.1.6;9.1.6 Editing Structure;156
7.1.1.6.1;Merging/Joining/Copying Datasets;158
7.1.1.7;9.1.7 Managing Missing Values;158
7.1.1.8;9.1.8 The Split-Apply-Combine Strategy;159
7.1.1.8.1;Aggregating;160
7.1.1.8.2;Computing the Cumulative Sum by Categories;162
7.1.1.9;9.1.9 Pivoting Data;163
7.1.1.9.1;Stacking Columns;165
7.1.1.9.2;Unstacking;165
7.1.1.9.3;The Pivot Function;167
7.1.1.9.4;Sorting;169
7.1.1.10;9.1.10 Dataframe Export;169
7.1.1.10.1;Exporting to CSV;169
7.1.1.10.2;Exporting to the OpenDocument Spreadsheet File;169
7.1.1.10.3;Exporting to a Matrix;170
7.1.1.10.4;Exporting to a Dict;170
7.1.1.10.5;Exporting to the hdf5 Format;171
7.1.2;9.2 Using IndexedTables;171
7.1.2.1;9.2.1 Creating an IndexedTable (NDSparse);172
7.1.2.2;9.2.2 Row Filtering;173
7.1.2.3;9.2.3 Editing/Adding Values;174
7.1.3;9.3 Using the Pipe Operator;174
7.1.4;9.4 Plotting;176
7.1.4.1;9.4.1 Installation and Backends;176
7.1.4.2;9.4.2 The Plot Function;179
7.1.4.3;9.4.3 Plotting from DataFrames;182
7.1.4.4;9.4.4 Saving;185
7.2;Chapter 10: Mathematical Libraries;186
7.2.1;10.1 JuMP, an Optimization Framework;187
7.2.1.1;10.1.1 The Transport Problem: A Linear Problem;189
7.2.1.1.1;The Problem;189
7.2.1.1.2;Importing the Libraries;190
7.2.1.1.3;Defining the Sets;190
7.2.1.1.4;Defining the Parameters;191
7.2.1.1.5;Declaring the Model;192
7.2.1.1.6;Declaring the Model Variables;193
7.2.1.1.7;Declaring the Model Constraints;193
7.2.1.1.8;Declaring the Model Objective;194
7.2.1.1.9;Human-Readable Visualization of the Model (Optional);194
7.2.1.1.10;Resolution of the Model;194
7.2.1.1.11;Visualization of the Results;195
7.2.1.2;10.1.2 Choosing Between Pizzas and Sandwiches, a Non-Linear Problem;197
7.2.1.2.1;The Problem;197
7.2.1.2.2;Importing the Libraries and Declaring the Model;198
7.2.1.2.3;Declaring the Model Variables, Constraints, and Objectives;198
7.2.1.2.4;Resolution of the Model and Visualization of the Results;199
7.2.2;10.2 SymPy, a CAS System;200
7.2.2.1;10.2.1 Loading the Library and Declaring Symbols;200
7.2.2.2;10.2.2 Creating and Manipulating Expressions;201
7.2.2.3;10.2.3 Solving a System of Equations;202
7.2.2.4;10.2.4 Retrieving Numerical Values;202
7.2.3;10.3 LsqFit, a Data Fit Library;203
7.2.3.1;10.3.1 Loading the Libraries and Defining the Model;204
7.2.3.2;10.3.2 Parameters;204
7.2.3.3;10.3.3 Fitting the Model;205
7.2.3.4;10.3.4 Retrieving the Parameters and Comparing them with the Observations;205
7.3;Chapter 11: Utilities;207
7.3.1;11.1 Weave for Dynamic Documents;207
7.3.2;11.2 Zip Files;211
7.3.2.1;11.2.1 Writing a Zip Archive;211
7.3.2.2;11.2.2 Reading from a Zipped Archive;212
7.3.3;11.3 Interact and Mux: Expose Interacting Models on the Web;214
7.3.3.1;11.3.1 Importing the Libraries;214
7.3.3.2;11.3.2 Defining the Logic of the Model;214
7.3.3.3;11.3.3 Defining Controls and Layout;215
7.3.3.4;11.3.4 Providing Widgets to Web Users;216
8;Index;218