Using different kernels

You can now choose a kernel for a notebook within the user interface, rather than starting up a separate notebook server for each kernel you want to use. The syntax highlighting adapts to match the language you're working in.

Information about the kernel is stored in the notebook file, so when you open a notebook, it will automatically start the correct kernel.

It is also easier to use the Qt console and the terminal console with other kernels, using the --kernel flag:

ipython qtconsole --kernel bash
ipython console --kernel bash

# To list available kernels
ipython kernelspec list

Kernel authors should see :ref:`kernelspecs` for how to register their kernels with IPython so that these mechanisms work.

Typing unicode identifiers

Complex expressions can be much cleaner when written with a wider choice of characters. Python 3 allows unicode identifiers, and IPython 3 makes it easier to type those, using a feature from Julia. Type a backslash followed by a LaTeX style short name, such as \alpha. Press tab, and it will turn into α.

Other new features

• :class:`~.TextWidget` and :class:`~.TextareaWidget` objects now include a placeholder attribute, for displaying placeholder text before the user has typed anything.

• The %load magic can now find the source for objects in the user namespace. To enable searching the namespace, use the -n option.

  In [1]: %load -n my_module.some_function
  

• :class:`~.DirectView` objects have a new :meth:`~.DirectView.use_cloudpickle` method, which works like view.use_dill(), but causes the cloudpickle module from PiCloud's cloud library to be used rather than dill or the builtin pickle module.

• Added a .ipynb exporter to nbconvert. It can be used by passing --to notebook as a commandline argument to nbconvert.

• New nbconvert preprocessor called :class:`~.ClearOutputPreprocessor`. This clears the output from IPython notebooks.

• New preprocessor for nbconvert that executes all the code cells in a notebook. To run a notebook and save its output in a new notebook:

  ipython nbconvert InputNotebook --ExecutePreprocessor.enabled=True --to notebook --output Executed
  

• Consecutive stream (stdout/stderr) output is merged into a single output in the notebook document. Previously, all output messages were preserved as separate output fields in the JSON. Now, the same merge is applied to the stored output as the displayed output, improving document load time for notebooks with many small outputs.

Backwards incompatible changes

• :func:`IPython.core.oinspect.getsource` call specification has changed:

  • oname keyword argument has been added for property source formatting
  • is_binary keyword argument has been dropped, passing True had previously short-circuited the function to return None unconditionally

• Removed the octavemagic extension: it is now available as oct2py.ipython.

• Creating PDFs with LaTeX no longer uses a post processor. Use nbconvert --to pdf instead of nbconvert --to latex --post pdf.

• Used https://github.com/jdfreder/bootstrap2to3 to migrate the Notebook to Bootstrap 3.

  Additional changes:

  • Set .tab-content .row 0px; left and right margin (bootstrap default is -15px;)
  • Removed height: @btn_mini_height; from .list_header>div, .list_item>div in tree.less
  • Set #header div margin-bottom: 0px;
  • Set #menus to float: left;
  • Set #maintoolbar .navbar-text to float: none;
  • Added no-padding convienence class.
  • Set border of #maintoolbar to 0px

• Accessing the container DOM object when displaying javascript has been deprecated in IPython 2.0 in favor of accessing element. Starting with IPython 3.0 trying to access container will raise an error in browser javascript console.

• IPython.utils.py3compat.open was removed: :func:`io.open` provides all the same functionality.

• The NotebookManager and /api/notebooks service has been replaced by a more generic ContentsManager and /api/contents service, which supports all kinds of files.

• The Dashboard now lists all files, not just notebooks and directories.

• The --script hook for saving notebooks to Python scripts is removed, use :samp:`ipython nbconvert --to python {notebook}` instead.

• The rmagic extension is deprecated, as it is now part of rpy2. See :mod:`rpy2.ipython.rmagic`.

• :meth:`~.KernelManager.start_kernel` and :meth:`~.KernelManager.format_kernel_cmd` no longer accept a executable parameter. Use the kernelspec machinery instead.

• The widget classes have been renamed from *Widget to *. The old names are still functional, but are deprecated. i.e. IntSliderWidget has been renamed to IntSlider.

• The ContainerWidget was renamed to Box and no longer defaults as a flexible box in the web browser. A new FlexBox widget was added, which allows you to use the flexible box model.