IJulia is a Julia-language backend combined with the Jupyter interactive environment (also used by IPython). This combination allows you to interact with the Julia language using Jupyter/IPython's powerful graphical notebook, which combines code, formatted text, math, and multimedia in a single document
First, install IPython; you may also want some scientific-Python packages (SciPy and Matplotlib). The simplest way to do this on Mac and Windows is by downloading the Anaconda package and running its installer. (Do not use Enthought Canopy/EPD.)
- Important: on Windows, the Anaconda installer window gives options Add Anaconda to the System Path and also Register Anaconda as default Python version of the system. Be sure to check these boxes.
Second, download Julia version 0.3
or later and run the installer. Then run the Julia application
(double-click on it); a window with a
julia> prompt will appear. At
the prompt, type:
to install IJulia.
- If you ran into a problem with the above steps, after fixing the
problem you can type
Pkg.build()to try to rerun the install scripts.
- If you tried it a while ago, try running
Pkg.update()and try again: this will fetch the latest versions of the Julia packages in case the problem you saw was fixed. Run
Pkg.build("IJulia")if your Julia version may have changed. If this doesn't work, try just deleting the whole
.juliadirectory in your home directory (on Windows, it is called
AppData\Roaming\julia\packagesin your home directory) and re-adding the packages.
- On MacOS, you currently need MacOS 10.7 or later; MacOS 10.6 doesn't work (unless you compile Julia yourself, from source code).
- If the browser opens the notebook and
1+1works but basic functions like
sin(3)don't work, then probably you are running Python and not Julia. Look in the upper-left corner of the notebook window: if it says IP[y]: Notebook then you are running Python. Probably this was because your
Pkg.add("IJulia")failed and you ignored the error.
- Internet Explorer 8 (the default in Windows 7) or 9 don't work with the notebook; use Firefox (6 or later) or Chrome (13 or later). Internet Explorer 10 in Windows 8 works (albeit with a few rendering glitches), but Chrome or Firefox is better.
- If the notebook opens up, but doesn't respond (the input label is
In[*]indefinitely), try running
ipython notebook(without Julia) to see if
1+1works in Python. If it is the same problem, then probably you have a firewall running on your machine (this is common on Windows) and you need to disable the firewall or at least to allow the IP address 127.0.0.1. (For the Sophos endpoint security software, go to "Configure Anti-Virus and HIPS", select "Authorization" and then "Websites", and add 127.0.0.1 to "Authorized websites"; finally, restart your computer.)
- Try running
ipython --versionand make sure that it prints
3.0.0or larger; earlier versions of IPython are no longer supported by IJulia.
Updating Julia and IJulia
Julia is improving rapidly, so it won't be long before you want to update to a more recent version. To update the packages only, keeping Julia itself the same, just run:
at the Julia prompt (or in IJulia).
If you download and install a new version of Julia from the Julia web
site, you will also probably want to update the packages with
Pkg.update() (in case newer versions of the packages are required
for the most recent Julia). In any case, if you install a new Julia
binary (or do anything that changes the location of Julia on your
computer), you must update the IJulia installation (to tell IPython
where to find the new Julia) by running
at the Julia command line (not in IJulia).
Running the IJulia Notebook
In Julia, at the
julia> prompt, you can type
using IJulia notebook()
to launch the IJulia notebook in your browser. Alternatively, you can run
A "dashboard" window like this should open in your web browser. Click on the New button and choose the Julia option to start a new "notebook". A notebook will combine code, computed results, formatted text, and images, just as in IPython. You can enter multiline input cells and execute them with shift-ENTER, and the menu items are mostly self-explanatory. Refer to the the IPython documentation for more information.
Using older IPython versions
While we strongly recommend using IPython version 3 or later (note that this
has nothing to do with whether you use Python version 2 or 3), we recognize
that in the short term some users may need to continue using IPython 2.x. You
can do this by checkout out the
ipython2 branch of the IJulia package:
Pkg.checkout("IJulia", "ipython2") Pkg.build("IJulia")
Analogous to the IPython.display.clear_output() function in IPython, IJulia provides a function:
to clear the output from the current input cell. If the optional
wait argument is
true, then the front-end waits to clear the
output until new output is available to replace it (to minimize
flickering). This is useful to make simple animations, via repeated
IJulia.clear_output(true) followed by calls to
display(...) to display a new animation frame.
Default display size
When Julia displays a large data structure such as a matrix, by default
it truncates the display to a given number of lines and columns. In IJulia,
this truncation is to 30 lines and 80 columns by default. You can change
this default by the
COLUMNS environment variables, respectively,
which can also be changed within IJulia via
ENV["LINES"] = 60).
(Like in the REPL, you can also display non-truncated data structures via
Manual installation of IPython
First, you will need to install a few prerequisites:
You need version 3.0 or later of IPython. Note that IPython 3.0 was released in February 2015, so the version pre-packaged with operating-system distribution is likely to be too old for the next few weeks or months. Until then, you may have to install IPython manually. On Mac and Windows systems, it is currently easiest to use the Anaconda Python installer.
To use the IPython notebook interface, which runs in your web browser and provides a rich multimedia environment, you will need to install the jsonschema, Jinja2, Tornado, and pyzmq (requires
apt-get install libzmq-devand possibly
pip install --upgrade --force-reinstall pyzmqon Ubuntu if you are using
pip) Python packages. (Given the pip installer,
pip install jsonschema jinja2 tornado pyzmqshould normally be sufficient.) These should have been automatically installed if you installed IPython itself via
You need Julia version 0.3 or later.
Once IPython 3.0+ and Julia 0.3+ are installed, you can install IJulia from a Julia console by typing:
This will download IJulia and a few other prerequisites, and will set up a Julia kernel for IPython.
If the command above returns an error, you may need to run
retry it, or possibly run
Pkg.build("IJulia") to force a rebuild.
Other IPython interface
Most people will use the notebook (browser-based) interface, but you
can also use the IPython
or IPython terminal interfaces by running
ipython qtconsole --kernel
ipython console --kernel julia-0.3, respectively.
0.3 with whatever major Julia version you are using.)
Differences from IPython
One difference from IPython is that the IJulia kernel currently does
not support "magics", which are special commands prefixed with
%% to execute code in a different language. This and other features
are under consideration in the IJulia
Debugging IJulia problems
If IJulia is crashing (e.g. it gives you a "kernel appears to have
died" message), you can modify it to print more descriptive error
messages to the terminal: edit your
IJulia/src/IJulia.jl file (in
.julia package directory) to change the line
verbose = false
at the top to
verbose = true and
const capture_stderr = true to
const capture_stderr = false. Then restart the kernel or open a new
notebook and look for the error message when IJulia dies