Interact Exercise 5

Imports

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



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%matplotlib inline
import matplotlib.pyplot as plt
import numpy as np
from IPython.html.widgets import interact, interactive, fixed
from IPython.html import widgets
from IPython.display import SVG

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:



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s = """
<svg width="100" height="100">
  <circle cx="50" cy="50" r="20" fill="aquamarine" />
</svg>
"""



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SVG(s)









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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.



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def draw_circle(width=100, height=100, cx=25, cy=25, r=5, fill='red'):
    """Draw an SVG circle.
    
    Parameters
    ----------
    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.
    """
    # YOUR CODE HERE
    s = "<svg width = '%s' height= '%s'> <circle cx='%s' cy='%s' r='%s' fill='%s' /> </svg>" %(width,height,cx,cy,r,fill) 
    display(SVG(s))
#     return SVG(s)



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draw_circle(cx=10, cy=10, r=10, fill='blue')



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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.



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# YOUR CODE HERE
w=interactive(draw_circle, width=fixed(300),height=fixed(300), cx=(0,300,1),cy=(0,300,1),r=(0,50,1),fill='red')

w



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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:



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# YOUR CODE HERE
from IPython.display import display
display(w)



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assert True # leave this to grade the display of the widget

Play with the sliders to change the circles parameters interactively.



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