Julia: Difference between revisions

(22 intermediate revisions by the same user not shown)

Line 1:

~~__FORCETOC__~~

Julia is a numerical computation and general purpose high-level programming language.

It's standout feature is its performance which allows libraries to be written in Julia directly.

In contrast, many libraries in [[R]] and [[Python]] are written in [[C]] or [[C++]] for performance purposes and accessed using Rcpp or Cython.

In contrast, many libraries in [[R]] and [[Python]] are written in [[C (programming language)]] or [[C++]] for performance purposes and accessed using Rcpp or Cython.

If necessary, you can still interface with other languages.

See [https://en.wikibooks.org/wiki/Introducing_Julia Introducing Julia] for a comprehensive guide on how to program in Julia.

Line 14:

Line 13:

Most items can be accessed from the Atom control palette <code>Ctrl + Shift + P</code>

Shortcuts:

* <code>Ctrl + Enter</code> Evaluate current selection

* <code>Ctrl + Enter</code> Evaluate current selection/section.

* <code>Shift + Enter</code> Evaluate current section and jump to next.

* <code>Shift + Enter</code> Evaluate current selection/section and jump to next.

==~~Basic~~ Usage==

==Usage==

===Package Management===

[https://www.simonwenkel.com/2018/10/06/a-brief-introduction-to-package-management-with-julia.html Guide]

Initializing a new project

====Initializing a new project====

cd project_folder

Line 28:

Line 27:

</syntaxhighlight>

Loading an existing project

====Loading an existing project====

cd project_folder

julia

using Pkg;

Pkg.activate(~~"./"~~);

Pkg.activate(@__DIR__);

Pkg.instantiate();

</syntaxhighlight>

===String Interpolation===

====Updating an existing project====

If the dependencies in <code>Project.toml</code> have been updated, you will need to run

<code>Pkg.resolve()</code> to install new packages and update your local <code>Manifest.toml</code>

using Pkg;

Pkg.activate(@__DIR__);

Pkg.resolve();

</syntaxhighlight>

To update the your dependencies, run <code>Pkg.update()</code>

using Pkg;

Pkg.activate(@__DIR__);

Pkg.update();

</syntaxhighlight>

====Other Pkg Commands====

You can see all the commands by typing <code>?</code> in the package manager.

* <code>add [packagename]</code> Add a package

* <code>update [packagename]</code> Update a specific package or all packages

* <code>remove [packagename]</code> Remove a package

* <code>status</code> Show the current Pkg directory and installed packages

===Basics===

====Functions====

You can chain functions using the pipe operator <code>|></code>. This is similar to <code>%>%</code> in [[R]] or <code>|></code> in [[F_sharp| F#]]

a = [1,2,3];

// Equivalent to sum(a)

b = a |> sum

</syntaxhighlight>

====Strings====

=====String Interpolation=====

"Variable x is $x, y is $y, and x+y is $(x+y)"

</syntaxhighlight>

===Arrays===

====String Concatenation====

Julia uses <code>*</code> to concatenate strings.

You will get an error if you use <code>+</code>.

"a"*"b"

</syntaxhighlight>

====Arrays====

[[https://en.wikibooks.org/wiki/Introducing_Julia/Arrays_and_tuples Full details]]

Line 51:

Line 91:

myArr = Array{Float64,1}(undef, 3)

// Convert ~~an iterable~~ to an array with collect

// Convert a collection to an array with collect

myArr = collect(1:3)

myArr = collect(1:0.5:3)

// myArr == [1.0,1.5,2.0,2.5,3.0]

// Reference copy

Line 100:

Line 141:

===Graphics===

==Graphics==

You can use MeshCat.jl to create visualizations to view in a web browser.

Line 108:

Line 149:

MeshCat.jl is built using [https://github.com/JuliaGizmos/WebIO.jl WebIO.jl].

===Machine Learning===

==Machine Learning==

See [[Flux]] and [[Knet.jl]]

==Object Oriented Programming==

===Object Oriented Programming===

Julia is a [https://en.wikipedia.org/wiki/Multiple_dispatch Multiple Dispatch] language.

You can use a <code>struct</code> in place of classes and define ~~functions~~ which ~~have~~ your struct as a parameter ~~in place~~ of methods.

You can use a <code>struct</code> in place of classes and define methods which use your struct as a parameter.

You can find all definitions of a function using the <code>methods</code> function.

For example:

Line 141:

Line 183:

supertype(Int64)

# Check if a is a subtype of b with <:

# This is the same symbol for creating a subtype

# This is the same symbol for creating a subtype of an abstract type

# E.g. mutable struct myNum <: Number

Int64 <: Number

Line 157:

Line 199:

It includes convenience features including NN layers, activation functions, and an automatic differentiation system.

See [[Machine Learning in Julia]] for more details on how to use Flux.

===Latexify.jl===

[https://github.com/korsbo/Latexify.jl Link]

Prints out a latex string for any Julia expression or value.

Very useful for printing out matrices to insert into Latex documents.

==References==

@@ Line 1: / Line 1: @@
-__FORCETOC__
 Julia is a numerical computation and general purpose high-level programming language.
 It's standout feature is its performance which allows libraries to be written in Julia directly.
-In contrast, many libraries in [[R]] and [[Python]] are written in [[C]] or [[C++]] for performance purposes and accessed using Rcpp or Cython.
+In contrast, many libraries in [[R]] and [[Python]] are written in [[C (programming language)]] or [[C++]] for performance purposes and accessed using Rcpp or Cython.
 If necessary, you can still interface with other languages.
 See [https://en.wikibooks.org/wiki/Introducing_Julia Introducing Julia] for a comprehensive guide on how to program in Julia.
@@ Line 14: / Line 13: @@
 Most items can be accessed from the Atom control palette <code>Ctrl + Shift + P</code><br>
 Shortcuts:
-* <code>Ctrl + Enter</code> Evaluate current selection
+* <code>Ctrl + Enter</code> Evaluate current selection/section.
-* <code>Shift + Enter</code> Evaluate current section and jump to next.
+* <code>Shift + Enter</code> Evaluate current selection/section and jump to next.
-==Basic Usage==
+==Usage==
 ===Package Management===
 [https://www.simonwenkel.com/2018/10/06/a-brief-introduction-to-package-management-with-julia.html Guide]
-Initializing a new project
+====Initializing a new project====
 <syntaxhighlight lang="bash">
 cd project_folder
@@ Line 28: / Line 27: @@
 </syntaxhighlight>
-Loading an existing project
+====Loading an existing project====
 <syntaxhighlight lang="bash">
 cd project_folder
 julia
 using Pkg;
-Pkg.activate("./");
+Pkg.activate(@__DIR__);
 Pkg.instantiate();
 </syntaxhighlight>
-===String Interpolation===
+====Updating an existing project====
+If the dependencies in <code>Project.toml</code> have been updated, you will need to run
+<code>Pkg.resolve()</code> to install new packages and update your local <code>Manifest.toml</code>
+<syntaxhighlight lang="bash">
+using Pkg;
+Pkg.activate(@__DIR__);
+Pkg.resolve();
+</syntaxhighlight>
+To update the your dependencies, run <code>Pkg.update()</code>
+<syntaxhighlight lang="bash">
+using Pkg;
+Pkg.activate(@__DIR__);
+Pkg.update();
+</syntaxhighlight>
+====Other Pkg Commands====
+You can see all the commands by typing <code>?</code> in the package manager.
+* <code>add [packagename]</code> Add a package
+* <code>update [packagename]</code> Update a specific package or all packages
+* <code>remove [packagename]</code> Remove a package
+* <code>status</code> Show the current Pkg directory and installed packages
+===Basics===
+====Functions====
+You can chain functions using the pipe operator <code>|></code>. This is similar to <code>%>%</code> in [[R]] or <code>|></code> in [[F_sharp| F#]]
+<syntaxhighlight lang="julia>
+a = [1,2,3];
+// Equivalent to sum(a)
+b = a |> sum
+</syntaxhighlight>
+====Strings====
+=====String Interpolation=====
 <syntaxhighlight lang="julia">
 "Variable x is $x, y is $y, and x+y is $(x+y)"
 </syntaxhighlight>
-===Arrays===
+====String Concatenation====
+Julia uses <code>*</code> to concatenate strings.
+You will get an error if you use <code>+</code>.
+<syntaxhighlight lang="julia">
+"a"*"b"
+</syntaxhighlight>
+====Arrays====
 [[https://en.wikibooks.org/wiki/Introducing_Julia/Arrays_and_tuples Full details]]
 <syntaxhighlight lang="julia">
@@ Line 51: / Line 91: @@
 myArr = Array{Float64,1}(undef, 3)
-// Convert an iterable to an array with collect
+// Convert a collection to an array with collect
-myArr = collect(1:3)
+myArr = collect(1:0.5:3)
+// myArr == [1.0,1.5,2.0,2.5,3.0]
 // Reference copy
@@ Line 100: / Line 141: @@
-===Graphics===
+==Graphics==
 {{Main|Graphics in Julia}}
 You can use MeshCat.jl to create visualizations to view in a web browser.<br>
@@ Line 108: / Line 149: @@
 MeshCat.jl is built using [https://github.com/JuliaGizmos/WebIO.jl WebIO.jl].<br>
-===Machine Learning===
+==Machine Learning==
 {{Main|Machine Learning in Julia}}
+See [[Flux]] and [[Knet.jl]]
+==Object Oriented Programming==
-===Object Oriented Programming===
 Julia is a [https://en.wikipedia.org/wiki/Multiple_dispatch Multiple Dispatch] language.<br>
-You can use a <code>struct</code> in place of classes and define functions which have your struct as a parameter in place of methods.<br>
+You can use a <code>struct</code> in place of classes and define methods which use your struct as a parameter.<br>
+You can find all definitions of a function using the <code>methods</code> function.
 For example:
 <syntaxhighlight lang="julia">
@@ Line 141: / Line 183: @@
 supertype(Int64)
 # Check if a is a subtype of b with <:
-# This is the same symbol for creating a subtype
+# This is the same symbol for creating a subtype of an abstract type
 # E.g. mutable struct myNum <: Number
 Int64 <: Number
@@ Line 157: / Line 199: @@
 It includes convenience features including NN layers, activation functions, and an automatic differentiation system.
 See [[Machine Learning in Julia]] for more details on how to use Flux.
+===Latexify.jl===
+[https://github.com/korsbo/Latexify.jl Link]<br>
+Prints out a latex string for any Julia expression or value.<br>
+Very useful for printing out matrices to insert into Latex documents.
+==References==
+{{Reflist}}