Interact Exercise 5

Imports

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



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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

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.
    """
    circle = """
<svg width= "%d" height= "%d"> 
    <circle cx= "%d" cy="%d" r="%d" fill= "%s"/> 
</svg>"""%(width,height,cx,cy,r,fill)
    display(SVG(circle))



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



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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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w = interactive(draw_circle, width = fixed(300), height = fixed(300), cx = (0,300), cy = (0,300,10), r = (0,50), fill = 'red');



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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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display(w)









    



---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-1-bb151daac4e8> in <module>()
----> 1 display(w)

NameError: name 'display' is not defined



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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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