Compatibility Tools

Some packages require a little extra help to work nicely with PythonCall.

Some of these are "fixes" that are silently applied for you, and some are just extra functions to bridge a gap. We aim to keep these as minimal as possible.

Stdlib

Whenever a Python exception is displayed by Julia, sys.last_traceback and friends are set. This allows the post-mortem debugger pdb.pm() to work. Disable by setting PythonCall.CONFIG.auto_sys_last_traceback = false.

Tabular data & Pandas

A pandas.DataFrame can be wrapped in Julia as a PyPandasDataFrame, providing a Tables.jl-compatible interface.

Furthermore, any Python object which can be converted to a PyTable (e.g. pandas.DataFrame can be converted to PyPandasDataFrame) satisfies the Tables.jl interface.

In the other direction, the following functions can be used to convert any Tables.jl-compatible table to a Python table.

PythonCall.pytableFunction
pytable(src, format=:pandas; ...)

Construct a Python table from the Tables.jl-compatible table src.

The format controls the type of the resulting table, and is one of:

  • :pandas: A pandas.DataFrame. Keyword arguments are passed to the DataFrame constructor.
  • :columns: A dict mapping column names to columns.
  • :rows: A list of rows, which are namedtuples.
  • :rowdicts: A list of rows, which are dicts.

MatPlotLib / PyPlot / Seaborn

MatPlotLib figures can be shown with Julia's display mechanism, like display(fig) or display(mime, fig).

This means that if you return a figure from a Jupyter or Pluto notebook cell, it will be shown. You can call display(plt.gcf()) to display the current figure.

We also provide a simple MatPlotLib backend: mpl.use("module://juliacall.matplotlib"). Now you can call plt.show() to display the figure with Julia's display mechanism. You can specify the format like plt.show(format="png").

GUIs (including MatPlotLib)

Event loops

If for example you wish to use PyPlot in interactive mode (matplotlib.pyplot.ion()) then activating the correct event loop will allow it to work.

PythonCall.event_loop_onFunction
event_loop_on(g::Symbol; interval=0.04, fix=false)

Activate an event loop for the GUI framework g, so that the framework can run in the background of a Julia session.

The event loop runs every interval seconds. If fix is true and g is a Qt framework, then fix_qt_plugin_path is called.

Supported values of g (and the Python module they relate to) are: :pyqt4 (PyQt4), :pyqt5 (PyQt5), :pyside (PySide), :pyside2 (PySide2), :gtk (gtk), :gtk3 (gi), :wx (wx), :tkinter (tkinter).

Qt path fix

PythonCall.fix_qt_plugin_pathFunction
fix_qt_plugin_path()

Try to set the QT_PLUGIN_PATH environment variable in Python, if not already set.

This fixes the problem that Qt does not know where to find its qt.conf file, because it always looks relative to sys.executable, which can be the Julia executable not the Python one when using this package.

If CONFIG.auto_fix_qt_plugin_path is true, then this is run automatically before PyQt4, PyQt5, PySide or PySide2 are imported.

IPython

If Python is running an IPython kernel, then:

  • Currently disabled: Julia's Base.stdout is set to Python's sys.stdout.
  • A PythonDisplay and IPythonDisplay are pushed onto Julia's display stack, so that display(x) goes to IPython if possible.