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"""Interact with functions using widgets."""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from __future__ import print_function
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try: # Python >= 3.3
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from inspect import signature, Parameter
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except ImportError:
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from IPython.utils.signatures import signature, Parameter
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from inspect import getcallargs
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from IPython.core.getipython import get_ipython
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from IPython.html.widgets import (Widget, Text,
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FloatSlider, IntSlider, Checkbox, Dropdown,
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Box, Button, DOMWidget, Output)
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from IPython.display import display, clear_output
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from IPython.utils.py3compat import string_types, unicode_type
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from IPython.utils.traitlets import HasTraits, Any, Unicode
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empty = Parameter.empty
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def _matches(o, pattern):
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"""Match a pattern of types in a sequence."""
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if not len(o) == len(pattern):
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return False
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comps = zip(o,pattern)
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return all(isinstance(obj,kind) for obj,kind in comps)
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def _get_min_max_value(min, max, value=None, step=None):
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"""Return min, max, value given input values with possible None."""
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if value is None:
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if not max > min:
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raise ValueError('max must be greater than min: (min={0}, max={1})'.format(min, max))
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value = min + abs(min-max)/2
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value = type(min)(value)
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elif min is None and max is None:
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if value == 0.0:
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min, max, value = 0.0, 1.0, 0.5
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elif value == 0:
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min, max, value = 0, 1, 0
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elif isinstance(value, (int, float)):
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min, max = (-value, 3*value) if value > 0 else (3*value, -value)
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else:
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raise TypeError('expected a number, got: %r' % value)
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else:
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raise ValueError('unable to infer range, value from: ({0}, {1}, {2})'.format(min, max, value))
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if step is not None:
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# ensure value is on a step
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r = (value - min) % step
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value = value - r
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return min, max, value
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def _widget_abbrev_single_value(o):
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"""Make widgets from single values, which can be used as parameter defaults."""
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if isinstance(o, string_types):
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return Text(value=unicode_type(o))
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elif isinstance(o, dict):
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return Dropdown(options=o)
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elif isinstance(o, bool):
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return Checkbox(value=o)
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elif isinstance(o, float):
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min, max, value = _get_min_max_value(None, None, o)
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return FloatSlider(value=o, min=min, max=max)
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elif isinstance(o, int):
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min, max, value = _get_min_max_value(None, None, o)
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return IntSlider(value=o, min=min, max=max)
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else:
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return None
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def _widget_abbrev(o):
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"""Make widgets from abbreviations: single values, lists or tuples."""
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float_or_int = (float, int)
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if isinstance(o, (list, tuple)):
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if o and all(isinstance(x, string_types) for x in o):
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return Dropdown(options=[unicode_type(k) for k in o])
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elif _matches(o, (float_or_int, float_or_int)):
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min, max, value = _get_min_max_value(o[0], o[1])
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if all(isinstance(_, int) for _ in o):
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cls = IntSlider
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else:
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cls = FloatSlider
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return cls(value=value, min=min, max=max)
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elif _matches(o, (float_or_int, float_or_int, float_or_int)):
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step = o[2]
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if step <= 0:
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raise ValueError("step must be >= 0, not %r" % step)
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min, max, value = _get_min_max_value(o[0], o[1], step=step)
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if all(isinstance(_, int) for _ in o):
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cls = IntSlider
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else:
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cls = FloatSlider
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return cls(value=value, min=min, max=max, step=step)
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else:
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return _widget_abbrev_single_value(o)
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def _widget_from_abbrev(abbrev, default=empty):
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"""Build a Widget instance given an abbreviation or Widget."""
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if isinstance(abbrev, Widget) or isinstance(abbrev, fixed):
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return abbrev
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widget = _widget_abbrev(abbrev)
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if default is not empty and isinstance(abbrev, (list, tuple, dict)):
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# if it's not a single-value abbreviation,
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# set the initial value from the default
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try:
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widget.value = default
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except Exception:
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# ignore failure to set default
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pass
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if widget is None:
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raise ValueError("%r cannot be transformed to a Widget" % (abbrev,))
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return widget
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def _yield_abbreviations_for_parameter(param, kwargs):
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"""Get an abbreviation for a function parameter."""
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name = param.name
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kind = param.kind
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ann = param.annotation
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default = param.default
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not_found = (name, empty, empty)
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if kind in (Parameter.POSITIONAL_OR_KEYWORD, Parameter.KEYWORD_ONLY):
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if name in kwargs:
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value = kwargs.pop(name)
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elif ann is not empty:
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value = ann
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elif default is not empty:
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value = default
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else:
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yield not_found
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yield (name, value, default)
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elif kind == Parameter.VAR_KEYWORD:
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# In this case name=kwargs and we yield the items in kwargs with their keys.
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for k, v in kwargs.copy().items():
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kwargs.pop(k)
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yield k, v, empty
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def _find_abbreviations(f, kwargs):
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"""Find the abbreviations for a function and kwargs passed to interact."""
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new_kwargs = []
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for param in signature(f).parameters.values():
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for name, value, default in _yield_abbreviations_for_parameter(param, kwargs):
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if value is empty:
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raise ValueError('cannot find widget or abbreviation for argument: {!r}'.format(name))
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new_kwargs.append((name, value, default))
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return new_kwargs
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def _widgets_from_abbreviations(seq):
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"""Given a sequence of (name, abbrev) tuples, return a sequence of Widgets."""
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result = []
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for name, abbrev, default in seq:
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widget = _widget_from_abbrev(abbrev, default)
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if not widget.description:
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widget.description = name
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widget._kwarg = name
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result.append(widget)
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return result
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def interactive(__interact_f, **kwargs):
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"""
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Builds a group of interactive widgets tied to a function and places the
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group into a Box container.
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Returns
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-------
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container : a Box instance containing multiple widgets
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Parameters
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----------
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__interact_f : function
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The function to which the interactive widgets are tied. The **kwargs
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should match the function signature.
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**kwargs : various, optional
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An interactive widget is created for each keyword argument that is a
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valid widget abbreviation.
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"""
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f = __interact_f
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co = kwargs.pop('clear_output', True)
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manual = kwargs.pop('__manual', False)
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kwargs_widgets = []
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container = Box()
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container.result = None
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container.args = []
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container.kwargs = dict()
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kwargs = kwargs.copy()
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new_kwargs = _find_abbreviations(f, kwargs)
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# Before we proceed, let's make sure that the user has passed a set of args+kwargs
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# that will lead to a valid call of the function. This protects against unspecified
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# and doubly-specified arguments.
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getcallargs(f, **{n:v for n,v,_ in new_kwargs})
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# Now build the widgets from the abbreviations.
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kwargs_widgets.extend(_widgets_from_abbreviations(new_kwargs))
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# This has to be done as an assignment, not using container.children.append,
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# so that traitlets notices the update. We skip any objects (such as fixed) that
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# are not DOMWidgets.
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c = [w for w in kwargs_widgets if isinstance(w, DOMWidget)]
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# If we are only to run the function on demand, add a button to request this
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if manual:
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manual_button = Button(description="Run %s" % f.__name__)
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c.append(manual_button)
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# Use an output widget to capture the output of interact.
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output = Output()
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c.append(output)
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container.children = c
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# Build the callback
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def call_f(name=None, old=None, new=None):
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with output:
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container.kwargs = {}
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for widget in kwargs_widgets:
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value = widget.value
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container.kwargs[widget._kwarg] = value
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if co:
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clear_output(wait=True)
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if manual:
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manual_button.disabled = True
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try:
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container.result = f(**container.kwargs)
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except Exception as e:
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ip = get_ipython()
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if ip is None:
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container.log.warn("Exception in interact callback: %s", e, exc_info=True)
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else:
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ip.showtraceback()
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finally:
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if manual:
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manual_button.disabled = False
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# Wire up the widgets
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# If we are doing manual running, the callback is only triggered by the button
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# Otherwise, it is triggered for every trait change received
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# On-demand running also suppresses running the function with the initial parameters
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if manual:
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manual_button.on_click(call_f)
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else:
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for widget in kwargs_widgets:
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widget.on_trait_change(call_f, 'value')
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container.on_displayed(lambda _: call_f(None, None, None))
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return container
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def interact(__interact_f=None, **kwargs):
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"""
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Displays interactive widgets which are tied to a function.
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Expects the first argument to be a function. Parameters to this function are
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widget abbreviations passed in as keyword arguments (**kwargs). Can be used
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as a decorator (see examples).
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Returns
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-------
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f : __interact_f with interactive widget attached to it.
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Parameters
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----------
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__interact_f : function
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The function to which the interactive widgets are tied. The **kwargs
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should match the function signature. Passed to :func:`interactive()`
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**kwargs : various, optional
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An interactive widget is created for each keyword argument that is a
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valid widget abbreviation. Passed to :func:`interactive()`
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Examples
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--------
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Renders an interactive text field that shows the greeting with the passed in
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text.
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1. Invocation of interact as a function
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def greeting(text="World"):
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print "Hello {}".format(text)
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interact(greeting, text="IPython Widgets")
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2. Invocation of interact as a decorator
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@interact
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def greeting(text="World"):
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print "Hello {}".format(text)
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3. Invocation of interact as a decorator with named parameters
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@interact(text="IPython Widgets")
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def greeting(text="World"):
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print "Hello {}".format(text)
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Renders an interactive slider widget and prints square of number.
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1. Invocation of interact as a function
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def square(num=1):
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print "{} squared is {}".format(num, num*num)
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interact(square, num=5)
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2. Invocation of interact as a decorator
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@interact
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def square(num=2):
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print "{} squared is {}".format(num, num*num)
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3. Invocation of interact as a decorator with named parameters
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@interact(num=5)
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def square(num=2):
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print "{} squared is {}".format(num, num*num)
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"""
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# positional arg support in: https://gist.github.com/8851331
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if __interact_f is not None:
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# This branch handles the cases 1 and 2
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# 1. interact(f, **kwargs)
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# 2. @interact
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# def f(*args, **kwargs):
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# ...
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f = __interact_f
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w = interactive(f, **kwargs)
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try:
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f.widget = w
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except AttributeError:
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# some things (instancemethods) can't have attributes attached,
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# so wrap in a lambda
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f = lambda *args, **kwargs: __interact_f(*args, **kwargs)
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f.widget = w
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display(w)
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return f
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else:
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# This branch handles the case 3
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# @interact(a=30, b=40)
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# def f(*args, **kwargs):
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# ...
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def dec(f):
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return interact(f, **kwargs)
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return dec
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def interact_manual(__interact_f=None, **kwargs):
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"""interact_manual(f, **kwargs)
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As `interact()`, generates widgets for each argument, but rather than running
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the function after each widget change, adds a "Run" button and waits for it
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to be clicked. Useful if the function is long-running and has several
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parameters to change.
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"""
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return interact(__interact_f, __manual=True, **kwargs)
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class fixed(HasTraits):
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"""A pseudo-widget whose value is fixed and never synced to the client."""
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value = Any(help="Any Python object")
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description = Unicode('', help="Any Python object")
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def __init__(self, value, **kwargs):
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super(fixed, self).__init__(value=value, **kwargs)
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