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PyJulia

Experimenting with developing a better interface to Julia language that works with Python 2 & 3 and Julia v0.6+.

to run the tests, execute from the toplevel directory

python -m unittest discover

Note You need to explicitly add julia to your PATH, an alias will not work.

pyjulia is tested against Python versions 2.7 and 3.5. Older versions of Python (than 2.7) are not supported.

Installation

You will need to install PyCall in your existing Julia installation

Pkg.add("PyCall")

Your python installation must be able to call Julia. If your installer does not add the Julia binary directory to your PATH, you will have to add it.

Then finally you have to install pyjulia.

To get released versions you can use:

pip install julia

You may clone it directly to your home directory.

git clone https://github.com/JuliaPy/pyjulia

then inside the pyjulia directory you need to run the python setup file

[sudo] pip install [-e] .

The -e flag makes a development install meaning that any change to pyjulia source tree will take effect at next python interpreter restart without having to reissue an install command.

pyjulia is known to work with PyCall.jl ≥ v0.7.2.

If you run into problems using pyjulia, first check the version of PyCall.jl you have installed by running Pkg.installed("PyCall").

Usage

To call Julia functions from python, first import the library

import julia

then create a Julia object that makes a bridge to the Julia interpreter (assuming that julia is in your PATH)

j = julia.Julia()

You can then call Julia functions from python, e.g.

j.sind(90)

How it works

PyJulia loads the libjulia library and executes the statements therein. To convert the variables, the PyCall package is used. Python references to Julia objects are reference counted by Python, and retained in the PyCall.pycall_gc mapping on the Julia side (the mapping is removed when reference count drops to zero, so that the Julia object may be freed).

Limitations

Not all valid Julia identifiers are valid Python identifiers. Unicode identifiers are invalid in Python 2.7 and so pyjulia cannot call or access Julia methods/variables with names that are not ASCII only. Additionally, it is a common idiom in Julia to append a ! character to methods which mutate their arguments. These method names are invalid Python identifers. pyjulia renames these methods by subsituting ! with _b. For example, the Julia method sum! can be called in pyjulia using sum_b(...).