Numpy Exercise 1

Imports



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import numpy as np
%matplotlib inline
import matplotlib.pyplot as plt
import seaborn as sns



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import antipackage
import github.ellisonbg.misc.vizarray as va

Checkerboard

Write a Python function that creates a square (size,size) 2d Numpy array with the values 0.0 and 1.0:

Your function should work for both odd and even size.
The 0,0 element should be 1.0.
The dtype should be float.



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def checkerboard(size):
    """Return a 2d checkboard of 0.0 and 1.0 as a NumPy array"""
    a = np.zeros((size,size))
    x=0
    while x < size:
        a[x,0] = 1
        x += 2
    for x in range(0,size):
        for y in range(1,size):
            a[x,y]= (-1)**(x+y) + a[x,y-1] 
    return a



In [38]:

    
checkerboard(4)









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array([[ 1.,  0.,  1.,  0.],
       [ 0.,  1.,  0.,  1.],
       [ 1.,  0.,  1.,  0.],
       [ 0.,  1.,  0.,  1.]])



In [37]:

    
a = checkerboard(4)
assert a[0,0]==1.0
assert a.sum()==8.0
assert a.dtype==np.dtype(float)
assert np.all(a[0,0:5:2]==1.0)
assert np.all(a[1,0:5:2]==0.0)

b = checkerboard(5)
assert b[0,0]==1.0
assert b.sum()==13.0
assert np.all(b.ravel()[0:26:2]==1.0)
assert np.all(b.ravel()[1:25:2]==0.0)

Use vizarray to visualize a checkerboard of size=20 with a block size of 10px.



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# YOUR CODE HERE
va.enable()
va.set_block_size(10)
checkerboard(20)









    Out[40]:



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assert True

Use vizarray to visualize a checkerboard of size=27 with a block size of 5px.



In [41]:

    
# YOUR CODE HERE
va.set_block_size(5)
checkerboard(27)









    Out[41]:



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assert True