Environment Variables#
ndv recognizes the following environment variables:
Boolean variables can be set to 1, 0, True, or False (case insensitive).
Variable | Description | Default |
|---|---|---|
NDV_CANVAS_BACKEND | Explicitly choose the graphics library: "vispy" or "pygfx" | auto |
NDV_GUI_FRONTEND | Explicitly choose the GUI library: "qt", "wx", or "jupyter" | auto |
NDV_DEBUG_EXCEPTIONS | Whether to drop into a debugger when an exception is raised. (for development) | False |
NDV_EXIT_ON_EXCEPTION | Whether to exit the application on the first unhandled exception. (for development) | False |
NDV_IPYTHON_MAGIC | Whether to use %gui magic when running in IPython, to enable interactive usage. | True |
NDV_SYNCHRONOUS | Whether to force data request/draw to be synchronous. (*note: this currently has no effect on Jupyter, which is always asynchronous) | False |
Framework selection#
Depending on how you've installed ndv, you may end up with multiple supported GUI or graphics libraries installed. You can control which ones ndv uses with NDV_CANVAS_BACKEND and NDV_GUI_FRONTEND, respectively, as described above. Note that currently, only one GUI framework can be used per session.
Defaults
GUI:
ndv tries to be aware of the GUI library you are using. So it will use jupyter if you are in a Jupyter notebook, qt if a QApplication is already running, and wx if a wx.App is already running. Finally, it will check for the availability of libraries in the order of qt, wx, jupyter.
Graphics:
If you have both VisPy and pygfx installed, ndv will (currently) default to using VisPy.