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from IPython.display import display
from IPython.display import (
display_png, display_html, display_latex,
display_javascript, display_svg
)
Write a simple MyCircle Python class. Here is a skeleton to get you started:
class MyCircle(object):
def __init__(self, center=(0.0,0.0), radius=1.0, color='blue'):
self.center = center
self.radius = radius
self.color = color
Now add special display methods to this class for the following representations (remember to wrap them in Python strings):
For HTML:
○
For SVG:
<svg width="100px" height="100px">
<circle cx="50" cy="50" r="20" stroke="black" stroke-width="1" fill="white"/>
</svg>
For LaTeX (wrap with $ and use a raw Python string):
\bigcirc
For JavaScript:
alert('I am a circle!');
After you write the class, create an instance and then use display_html, display_svg, display_latex and display_javascript to display those representations.
Here is the solution to the simple MyCircle class:
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%load soln/mycircle.py
Now create an instance and use the display methods:
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c = MyCircle()
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display(c)
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display_html(c)
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display_svg(c)
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display_latex(c)
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display_javascript(c)
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%matplotlib inline
from matplotlib import pyplot as plt
Now let's assume that the MyCircle class has already been defined and add a PNG representation using a formatter display function. Here is a function that converts a MyCircle instance to raw PNG data.
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from IPython.core.pylabtools import print_figure
def circle_to_png(circle):
"""Render AnotherCircle to png data using matplotlib"""
fig, ax = plt.subplots()
patch = plt.Circle(circle.center,
radius=circle.radius,
fc=circle.color,
)
ax.add_patch(patch)
plt.axis('scaled')
data = print_figure(fig, 'png')
# We MUST close the figure, otherwise IPython's display machinery
# will pick it up and send it as output, resulting in a double display
plt.close(fig)
return data
Now use the IPython API to get the PNG formatter (image/png) and call the for_type method to register circle_to_png as the display function for MyCircle.
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%load soln/mycircle_png.py
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display_png(c)
In this exercise, you will register a display formatter function that generates a PNG representation of a 2d NumPy array. Here is the function that uses the Python Imaging Library (PIL) to generate the raw PNG data:
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from PIL import Image
from io import BytesIO
import numpy as np
def ndarray_to_png(x):
if len(x.shape) != 2: return
x = np.asarray(Image.fromarray(x).resize((500, 500)))
x = (x - x.min()) / (x.max() - x.min())
img = Image.fromarray((x*256).astype('uint8'))
img_buffer = BytesIO()
img.save(img_buffer, format='png')
return img_buffer.getvalue()
Use the for_type method of the PNG formatter to register ndarray_to_png as the display function for np.ndarray.
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%load soln/ndarray_png.py
Now create a few NumPy arrays and display them. Notice that their default representation in the Notebook is PNG rather than text.
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a = np.random.rand(100,100)
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a
You can still display the plain text representation using the display_pretty function.
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from IPython.display import display_pretty
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display_pretty(a)
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b = np.linspace(0,100.0, 100**2).reshape((100,100))
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b