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]:

    
# there's got to be a more efficient way using some sort 
# of list comprehension

def checkerboard(size):
    cb = np.ones((size,size), dtype = float)
    for i in range(size):
        for j in range(size):
            if(i+j) % 2 == 1:
                cb[i,j] = 0.0
    return cb
    
checkerboard(4)









    Out[3]:





array([[ 1.,  0.,  1.,  0.],
       [ 0.,  1.,  0.,  1.],
       [ 1.,  0.,  1.,  0.],
       [ 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.enable()
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.enable()
checkerboard(27)









    Out[7]:



In [8]:

    
assert True