How to import custom module in julia

julia current module
julia reload module
julia find module
julia load file
julia module export all
julia warning: replacing module
julia add path
julia require file

I have a module I wrote here:

# Hello.jl
module Hello
    function foo
        return 1
    end
end

and

# Main.jl
using Hello
foo()

When I run the Main module:

$ julia ./Main.jl

I get this error:

ERROR: LoadError: ArgumentError: Hello not found in path
 in require at ./loading.jl:249
 in include at ./boot.jl:261
 in include_from_node1 at ./loading.jl:320
 in process_options at ./client.jl:280
 in _start at ./client.jl:378
while loading /Main.jl, in expression starting on line 1

You should include("./Hello.jl") before using Hello

Modules · The Julia Language, I found some documentation on the Module-command, but none on how to add custom modules to JULIA_PATH so I can import my functions to my new projects. After installation, to start using functions and definitions from the module, you tell Julia to make the code available to your current session, with the using or import statements, which accept the names of one or more installed modules: julia> using Calculus julia> On success, all the definitions in the Calculus module are available for use.

There is a new answer to this question since the release of Julia v0.7 and v1.0 that is slightly different. I just had to do this so I figured I'd post my findings here.

As already explained in other solutions, it is necessary to include the relevant script which defines the module. However, since the custom module is not a package, it cannot be loaded as a package with the same using or import commands as could be done in older Julia versions.

So the Main.jl script would be written with a relative import like this:

include("./Hello.jl")
using .Hello
foo()

I found this explained simply in Stefan Karpinski's discourse comment on a similar question. As he describes, the situation can also get more elaborate when dealing with submodules. The documentation section on module paths is also a good reference.

Introducing Julia/Modules and packages, a.jl and b.jl both lokk like this. module A import ..U f = U.f g = U.g export f, g end. so one dot as a prefix looks in the namespace of the current  Large modules can take several seconds to load because executing all of the statements in a module often involves compiling a large amount of code. Julia creates precompiled caches of the module to reduce this time. The incremental precompiled module file are created and used automatically when using import or using to load a module. This will cause it to be automatically compiled the first time it is imported.

There have already been some short answers, but I wanted to provide a more complete answer if possible.

When you run using MyModule, Julia only searches for it in a list of directories known as your LOAD_PATH. If you type LOAD_PATH in the Julia REPL, you will get something like the following:

2-element Array{ByteString,1}:
 "/Applications/Julia-0.4.5.app/Contents/Resources/julia/local/share/julia/site/v0.4"
 "/Applications/Julia-0.4.5.app/Contents/Resources/julia/share/julia/site/v0.4"

These are the directories that Julia will search for modules to include when you type using Hello. In the example that you provided, since Hello was not in your LOAD_PATH, Julia was unable to find it.

If you wish to include a local module, you can specify its location relative to your current working directory.

julia> include("./src/Hello.jl")

Once the file has been included, you can then run using Hello as normal to get all of the same behavior. For one off scripts, this is probably the best solution. However, if you find yourself regular having to include() a certain set of directories, you can permanently add them to your LOAD_PATH.

Adding directories to LOAD_PATH

Manually adding directories to your LOAD_PATH can be a pain if you wish to regularly use particular modules that are stored outside of the Julia LOAD_PATH. In that case, you can append additional directories to the LOAD_PATH environment variable. Julia will then automatically search through these directories whenever you issue an import or using command.

One way to do this is to add the following to your .basrc, .profile, .zshrc.

export JULIA_LOAD_PATH="/path/to/module/storage/folder"

This will append that directory onto the standard directories that Julia will search. If you then run

julia> LOAD_PATH

It should return

3-element Array{ByteString,1}:
 "/path/to/module/storage/folder"
 "/Applications/Julia-0.4.5.app/Contents/Resources/julia/local/share/julia/site/v0.4"
 "/Applications/Julia-0.4.5.app/Contents/Resources/julia/share/julia/site/v0.4"

You can now freely run using Hello and Julia will automatically find the module (as long as it is stored underneath /path/to/module/storage/folder.

For more information, take a look at this page from the Julia Docs.

How do you add custom Julia modules to Julia path : Julia, Once a variable is imported this way (or, equivalently, with the import keyword), a module may not create its own variable with the same name. Imported variables  Well, the only reason for you to have a setup.py file and all the __init__.py files in this folder is if you want to use my_project like a package. In order to install that package into Python, you would need to run python setup.py. However, if you don't want to use my_project like a package, but rather just as a collection of modules, then

Though 张实唯's answer is the most convenient, you should not use include outside the REPL. If you're writing a program file, go through the trouble of adding the appropriate directory to the LOAD_PATH. Remy gives a very good explanation of how to do so, but it's worth also explaining why you should do so in the first place. (Additionally from the docs: push!(LOAD_PATH, "/Path/To/My/Module/") but note your module and your file have to have the same name)

The problem is that anything you include will be defined right where you call include even if it is also defined elsewhere. Since the goal of modules is re-use, you'll probably eventually use MyModule in more than one file. If you call include in each file, then each will have its own definition of MyModule, and even though they are identical, these will be different definitions. That means any data defined in the MyModule (such as data types) will not be the same.

To see why this is a huge problem, consider these three files:

types.jl

module TypeModule
struct A end
export A
end

a_function.jl

include("types.jl")
module AFunctionModule
using TypeModule
function takes_a(a::A)
    println("Took A!")
end
export takes_a
end

function_caller.jl

include("a_function.jl")
include("types.jl")
using TypeModule, AFunctionModule
my_a = A()
takes_a(my_a)

If you run julia function_caller.jl you'll get MethodError: no method matching takes_a(::TypeModule.A). This is because the type A used in function_caller.jl is different from the one used in a_function.jl. In this simple case, you can actually "fix" the problem by reversing the order of the includes in function_caller.jl (or just by deleting include("types.jl") entirely from function_caller.jl! That's not good!). But what if you wanted another file b_function.jl that also used a type defined in TypeModule? You would have to do something very hacky. Or you could just modify your LOAD_PATH so the module is only defined once.

EDIT in response to xji: To distribute a module, you'd use Pkg (docs). I understood the premise of this question to be a custom, personal module.

Incidentally, if you really don't like the idea of modifying your load path (even if it's only within the scope of a single script...) you could symlink your module into a package directory (e.g. ~/.julia/v0.6/MyModule/MyModule.jl) and then Pkg.add(MyModule) and then import as normal. I find that to be a bit more trouble.

How to import module from another file in same directory?, I have a module I wrote here: # Hello.jl module Hello function foo return 1 end end and # Main.jl using Hello foo() When I run the Main module: $ julia ./Main.jl I​  1 Answer 1. The Julia Modules documentation states: The import keyword [] only operates on a single name at a time. It does not add modules to be searched the way using does. import also differs from using in that functions must be imported using import to be extended with new methods.

Unless you explicitly load the file (include("./Hello.jl")) Julia looks for module files in directories defined in the LOAD_PATH variable.

See this page.

Modules, I have a module I wrote here: # Hello.jl module Hello function foo return 1 end end. and # Main.jl using Hello foo(). When I run the Main module: $ julia ./Main.jl. pylab is the name for the Python module that includes matplotlib and numpy in a single namespace, according to matplotlib’s docs; it is the recommended interface to matplotlib. @pyimport is a Julia macro that is equivalent to a using statement on the Julia equivalent of the Python module.

How to import custom module in julia - julia - iOS, We recommend that you use PkgTemplates for creating new packages instead of module HelloWorld import Random import JSON greet() = print("Hello World! Calling Python functions from the Julia language. This package provides the ability to directly call and fully interoperate with Python from the Julia language.You can import arbitrary Python modules from Julia, call Python functions (with automatic conversion of types between Julia and Python), define Python classes from Julia methods, and share large data structures between Julia and Python

julia: How to import custom module in julia, Python Module Search Path. While importing a module, Python looks at several places. Interpreter first looks for a built-in module. Then(if built-in module not found), Python looks into a list of directories defined in sys.path. The search is in this order. The current directory. PYTHONPATH (an environment variable with a list of directories).

5. Creating Packages · Pkg.jl, A package can only be loaded once per Julia session. If you have run import Example in the current Julia session, you will have to restart Julia and rerun activate tutorial in the Pkg REPL. Revise.jl can make this process significantly more pleasant, but setting it up is beyond the scope of this guide.

Comments
  • What is the signigicance of using then? I thought this kw would include the module for me...
  • @dopatraman using is to introduce the names of a module into current scope, while the module itself won't be include() automaticlly (except for those in "LOAD_PATH")
  • If you have definitions inside a module, you also need to export them.
  • The second link is dead. Information as of this writing is available here: docs.julialang.org/en/v1/manual/modules/#Modules-and-files-1
  • I'm using Julia 1.2 and it appears it is not necessary to use the using .name statement anymore. Executing include("./name") is enough to import the file and its functions into the current script.
  • @theferrit32 include and using differ essentially. Much like C/C++, include brings the source code of the specified file into the calling file as if one had written the other file directly within the calling file. using on the other hand is not concerned with files (unless a file with the same name is found in the LOAD_PATH). It is used to import symbols of a specific module into the calling module. One may define multiple modules per file, and each module would need to call using or import on the sibling modules in order to access their functions.
  • That actually doesn't seem to be portable if the program is to be distributed and run on other users' systems right? In this way every user will have to modify their environment variable just to run every new Julia program on their system?
  • @xji No; this is just for loading libraries from Julia and this works exactly like C, Python etc. If you want to run a Julia program, julia myprogram.jl (just like python myprogram.py). However if you want to import a library into a Julia program, Julia needs to know where to look - just like GCC/Clang needs to know where to look for non-system C/C++ header files, or Python needs to know where to look for non-system or user-installed packages. There is no portable alternative for any language. If you don't want to modify your path, install the package with the Julia package manager.
  • for Julia >= 0.7, see @kiliantics answer stackoverflow.com/a/52298205/2822346. Basically, you need to add a . to make relative import after the include statement
  • That actually doesn't seem to be portable if the program is to be distributed and run on other users' systems right? In this way every user will have to modify their environment variable just to run every new Julia program on their system?