Interact Exercise 5


Put the standard imports for Matplotlib, Numpy and the IPython widgets in the following cell.

In [3]:
from matplotlib import pyplot as plt
import numpy as np
from IPython.display import SVG
from IPython.display import display
from IPython.html.widgets import interactive, fixed

:0: FutureWarning: IPython widgets are experimental and may change in the future.

Interact with SVG display

SVG is a simple way of drawing vector graphics in the browser. Here is a simple example of how SVG can be used to draw a circle in the Notebook:

In [4]:
s = """
<svg width="100" height="100">
  <circle cx="50" cy="50" r="20" fill="aquamarine" />

In [5]:


Write a function named draw_circle that draws a circle using SVG. Your function should take the parameters of the circle as function arguments and have defaults as shown. You will have to write the raw SVG code as a Python string and then use the IPython.display.SVG object and IPython.display.display function.

In [6]:
def draw_circle(width=100, height=100, cx=25, cy=25, r=5, fill='red'):
    """Draw an SVG circle.
    width : int
        The width of the svg drawing area in px.
    height : int
        The height of the svg drawing area in px.
    cx : int
        The x position of the center of the circle in px.
    cy : int
        The y position of the center of the circle in px.
    r : int
        The radius of the circle in px.
    fill : str
        The fill color of the circle.
    circ_image = """
<svg width="%d" height="%d">
  <circle cx="%d" cy="%d" r="%d" fill="%s" />

In [7]:
draw_circle(cx=10, cy=10, r=10, fill='blue')

In [8]:
assert True # leave this to grade the draw_circle function

Use interactive to build a user interface for exploing the draw_circle function:

  • width: a fixed value of 300px
  • height: a fixed value of 300px
  • cx/cy: a slider in the range [0,300]
  • r: a slider in the range [0,50]
  • fill: a text area in which you can type a color's name

Save the return value of interactive to a variable named w.

In [11]:
w = interactive(draw_circle,width = fixed(300),height = fixed(300),cx = (0,300),cy = (0,300,10),r = (0,50), fill  = "red")

In [12]:
c = w.children
assert c[0].min==0 and c[0].max==300
assert c[1].min==0 and c[1].max==300
assert c[2].min==0 and c[2].max==50
assert c[3].value=='red'

Use the display function to show the widgets created by interactive:

In [13]:

In [ ]:
assert True # leave this to grade the display of the widget

Play with the sliders to change the circles parameters interactively.