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









    



Downloading:  https://raw.githubusercontent.com/ellisonbg/misc/master/vizarray.py
Using existing version:  github.ellisonbg.misc.vizarray

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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va.enable()



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def checkerboard(size):
    k = np.zeros((size,size))
    for i in range(size):
        if size %2 == 0:
            k[i,i%2:size:2] = 1.0
        elif size %2 == 1:
            k[i,i%2:size+1:2] = 1.0
    return k

print checkerboard(4)









    



[[ 1.  0.  1.  0.]
 [ 0.  1.  0.  1.]
 [ 1.  0.  1.  0.]
 [ 0.  1.  0.  1.]]



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va.vizarray(checkerboard(5))









    Out[42]:



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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
# raise NotImplementedError()
m = checkerboard(20)
va.set_block_size(10)
va.vizarray(m)









    Out[45]:



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assert True

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



In [47]:

    
# YOUR CODE HERE
# raise NotImplementedError()
r = checkerboard(27)
va.set_block_size(5)
va.vizarray(r)









    Out[47]:



In [48]:

    
assert True



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def checkerboard(w, h) :
    re = np.r_[ w*[0,1] ]
    ro = np.r_[ w*[1,0] ]
    return np.row_stack(h*(re, ro))


AB = checkerboard(5, 10)



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va.enable()



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def gen_checkerboard(size):
    even = 1 * [0,1]
    odd = 1* [1,0]
    checkerboard = np.row_stack(size/2*(even, odd))
    return checkerboard.repeat(size, axis = 0)
print (gen_checkerboard(2))









    



[[0 1]
 [0 1]
 [1 0]
 [1 0]]



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