Numpy Exercise 1

Imports



In [2]:

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



In [3]:

    
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 [5]:

    
def checkerboard(size):
    """Return a 2d checkboard of 0.0 and 1.0 as a NumPy array"""
    check = np.zeros((size,size),float)
    check.fill(0.0)
    n = 0
    while n<(size):
        if n % 2 == 0: #For even number rows, start filling 1's at position 0
            p = 0
        else:         #For odd number rows, start filling 1's at position 1
            p = 1
        while p<(size):
            check[n,p] = (1.0)  #Fill 1's at position n,p
            p = p + 2    #Skip one position in row before filling in a row (Key to the checkerboard pattern)
        n = n + 1  #Move to next row
        
    return check

#print (checkerboard(7))    #Was used to test output
#raise NotImplementedError()









    



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



In [55]:

    
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 [59]:

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









    Out[59]:



In [ ]:

    
assert True

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



In [60]:

    
va.set_block_size(5)
va.vizarray(checkerboard(27))
#raise NotImplementedError()









    Out[60]:



In [ ]:

    
assert True