Numpy Exercise 1

Imports



In [92]:

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



In [1]:

    
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.



In [120]:

    
def checkerboard(size):
    Z = np.empty((size,size),dtype=float)
    Z.fill(1.0)
    Z[1::2,::2] = 0.0
    Z[::2,1::2] = 0.0
    return Z
va.vizarray(Z)

checkerboard(4)









    Out[120]:





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



In [121]:

    
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.



In [126]:

    
va.enable()
va.set_block_size(10)
checkerboard(20)









    Out[126]:



In [ ]:

    
assert True

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



In [127]:

    
va.set_block_size(5)
checkerboard(27)









    Out[127]:



In [ ]:

    
assert True