Simple Widget Introduction¶
What are widgets?¶
Widgets are eventful python objects that have a representation in the browser, often as a control like a slider, textbox, etc.
What can they be used for?¶
To use the widget framework, you need to import
from ipywidgets import *
Widgets have their own display
repr which allows them to be
displayed using IPython’s display framework. Constructing and returning
IntSlider automatically displays the widget (as seen below).
Widgets are displayed inside the widget area, which sits between the
code cell and output. You can hide all of the widgets in the widget area
by clicking the grey x in the margin.
You can also explicitly display the widget using
from IPython.display import display w = IntSlider() display(w)
Multiple display() calls¶
If you display the same widget twice, the displayed instances in the front-end will remain in sync with each other. Try dragging the slider below and watch the slider above.
Why does displaying the same widget twice work?¶
Widgets are represented in the back-end by a single object. Each time a widget is displayed, a new representation of that same object is created in the front-end. These representations are called views.
You can close a widget by calling its
All of the IPython widgets share a similar naming scheme. To read the
value of a widget, you can query its
w = IntSlider() display(w)
Similarly, to set a widget’s value, you can set its
w.value = 100
In addition to
value, most widgets share
visible. To see the entire list of synchronized,
stateful properties of any specific widget, you can query the
['readout_format', 'description', 'readout', '_model_module_version', 'min', '_model_module', '_range', '_view_module', 'layout', '_view_name', 'continuous_update', 'msg_throttle', 'orientation', 'step', 'max', '_dom_classes', '_model_name', 'style', '_view_module_version', 'value', 'disabled']
Shorthand for setting the initial values of widget properties¶
While creating a widget, you can set some or all of the initial values of that widget by defining them as keyword arguments in the widget’s constructor (as seen below).
Text(value='Hello World!', disabled=True)
Linking two similar widgets¶
If you need to display the same value two different ways, you’ll have to
use two different widgets. Instead of attempting to manually synchronize
the values of the two widgets, you can use the
function to link two properties together. Below, the values of two
widgets are linked together.
a = FloatText() b = FloatSlider() display(a,b) mylink = jslink((a, 'value'), (b, 'value'))