Numpy Exercise 1

Imports



In [1]:

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



In [2]:

    
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 [95]:

    
def checkerboard(size):
    #Create a 2x2 diagonal array
    x = np.diag((1.0, 1.0))
    #If the size is even, the array is tiled
    if size % 2 == 0:
        checkers = np.tile(x, (size/2, size/2))
    #If the size is odd, the array is tiled larger
    else:
        board = np.tile(x, ((size + 1)/2, (size + 1)/2))
        #The extra row is removed, the matrix is transponsed, and the new extra row is removed
        remove = np.delete(board, size, 0)
        trans = np.transpose(remove)
        checkers = np.delete(trans, size, 0)
    return checkers
    
            
    
    
    
    
    
print checkerboard(4)









    



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



In [96]:

    
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 [98]:

    
va.set_block_size(10)
va.enable()

checkerboard(20)









    Out[98]:



In [99]:

    
assert True

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



In [101]:

    
va.set_block_size(5)
checkerboard(27)









    Out[101]:



In [102]:

    
assert True



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