Calling your Python functions with graphical controls¶
We need to import a few functions from IPython.
import IPython.html.widgets as widgets
from IPython.html.widgets import interact, interactive, fixed
Let's create a simple function.
def f(x):
print("%d^2=%d" % (x, x*x))
f(3)
3^2=9
To make our function interactive, we add the decorator @interact. The argument to @interact specifies the domain for the x argument. IPython understands that (0, 10) means "a slider with an integer ranging from 0 to 10".
@interact(x=(0, 10))
def f(x):
print("%d^2=%d" % (x, x*x))
5^2=25
We can set a default value easily.
@interact(x=(0, 10))
def f(x=3):
print("%d^2=%d" % (x, x*x))
3^2=9
Widget abbreviations¶
Other controls can be created easily:
- checkbox
- text area
- slider
- dropdown
Here is a complete example.
import numpy as np
import matplotlib.pyplot as plt
%matplotlib inline
@interact(fun=('sin', 'cos', 'arctan'), # dropdown menu
title='my function', # text area
dashed=False, # checkbox
xscale=(.1, 100.)) # float slider
def complex_plot(fun='sin',
title='sine',
dashed=False,
xscale=5.):
f = getattr(np, fun)
t = np.linspace(-xscale, +xscale, 1000)
s = '--' if dashed else '-'
plt.plot(t, f(t), s, lw=3);
plt.xlim(-xscale, +xscale);
plt.title(title);
IPython adopts the following conventions, called widget abbreviations.
| Keyword argument | Widget |
True or False | CheckboxWiget |
'Hi there' | TextareaWidget |
value or (min,max) or (min,max,step) if integers are passed | IntSliderWidget |
value or (min,max) or (min,max,step) if floats are passed | FloatSliderWidget |
('orange','apple') or {'one':1,'two':2} | DropdownWidget |
More widgets¶
For more fine-grained control, it is possible to specify widgets explicitly. A widget is just a graphical control like a dropdown list, a button, or a slider. Here is the list of all available widgets:
[widget for widget in dir(widgets) if widget.endswith('Widget')]
['AccordionWidget', 'BoundedFloatTextWidget', 'BoundedIntTextWidget', 'ButtonWidget', 'CheckboxWidget', 'ContainerWidget', 'DOMWidget', 'DropdownWidget', 'FloatProgressWidget', 'FloatSliderWidget', 'FloatTextWidget', 'HTMLWidget', 'ImageWidget', 'IntProgressWidget', 'IntSliderWidget', 'IntTextWidget', 'LatexWidget', 'PopupWidget', 'RadioButtonsWidget', 'SelectWidget', 'TabWidget', 'TextWidget', 'TextareaWidget', 'ToggleButtonWidget', 'ToggleButtonsWidget', 'Widget']
We're going to replace a few widgets: the checkbox by a toggle button, and the dropdown list by a sequence of radio buttons. The first step is to recover the widget instance created with @interact.
interact(complex_plot,
title='my function',
xscale=(.1, 100.),
fun=widgets.RadioButtonsWidget(values=['sin', 'cos', 'arctan']),
dashed=widgets.ToggleButtonWidget(),);
This would also work with custom widgets.