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 [3]:

    
def checkerboard(size):
    """Return a 2d checkboard of 0.0 and 1.0 as a NumPy array"""
    array = np.zeros((size,size),dtype=np.float)
    # I slice through specific entries to add the ones in the necessary places
    array[0:size:2,0:size:2] = 1.0
    array[1:size:2,1:size:2] = 1.0
    return array
print(checkerboard(5))









    



[[ 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 [4]:

    
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 [5]:

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









    Out[5]:



In [6]:

    
assert True

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



In [7]:

    
va.set_block_size(5)
va.vizarray(checkerboard(27))









    Out[7]:



In [8]:

    
assert True