Warning

This documentation covers a development version of IPython. The development version may differ significantly from the latest stable release.

Important

This documentation covers IPython versions 6.0 and higher. Beginning with version 6.0, IPython stopped supporting compatibility with Python versions lower than 3.3 including all versions of Python 2.7.

If you are looking for an IPython version compatible with Python 2.7, please use the IPython 5.x LTS release and refer to its documentation (LTS is the long term support release).

Integrating your objects with IPython

Tab completion

To change the attributes displayed by tab-completing your object, define a __dir__(self) method for it. For more details, see the documentation of the built-in dir() function.

You can also customise key completions for your objects, e.g. pressing tab after obj["a. To do so, define a method _ipython_key_completions_(), which returns a list of objects which are possible keys in a subscript expression obj[key].

New in version 5.0: Custom key completions

Rich display

The notebook and the Qt console can display richer representations of objects. To use this, you can define any of a number of _repr_*_() methods. Note that these are surrounded by single, not double underscores.

Both the notebook and the Qt console can display svg, png and jpeg representations. The notebook can also display html, javascript, markdown and latex. If the methods don’t exist, or return None, it falls back to a standard repr().

For example:

class Shout(object):
    def __init__(self, text):
        self.text = text

    def _repr_html_(self):
        return "<h1>" + self.text + "</h1>"

There are also two more powerful display methods:

class MyObject

_repr_mimebundle_(include=None, exclude=None)

Should return a dictionary of multiple formats, keyed by mimetype, or a tuple of two dictionaries: data, metadata. If this returns something, other _repr_*_ methods are ignored. The method should take keyword arguments include and exclude, though it is not required to respect them.

_ipython_display_()

Displays the object as a side effect; the return value is ignored. If this is defined, all other display methods are ignored.

Formatters for third-party types

The user can also register formatters for types without modifying the class:

from bar import Foo

def foo_html(obj):
    return '<marquee>Foo object %s</marquee>' % obj.name

html_formatter = get_ipython().display_formatter.formatters['text/html']
html_formatter.for_type(Foo, foo_html)

# Or register a type without importing it - this does the same as above:
html_formatter.for_type_by_name('bar.Foo', foo_html)

Custom exception tracebacks

Rarely, you might want to display a custom traceback when reporting an exception. To do this, define the custom traceback using _render_traceback_(self) method which returns a list of strings, one string for each line of the traceback. For example, the ipyparallel a parallel computing framework for IPython, does this to display errors from multiple engines.

Please be conservative in using this feature; by replacing the default traceback you may hide important information from the user.