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 [4]:

    
def checkerboard(size):
    """Return a 2d checkboard of 0.0 and 1.0 as a NumPy array"""
    c=np.empty((size,size,)) #this makes the array
    for i in range(size):    
        for j in range(size):#gives the size of the matrix as defined by the imput
            if (i+j)%2==0:
                c[i,j]=1
            else:
                c[i,j]=0
    return c
print checkerboard(8) #needed to check to make sure this was working









    



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



In [42]:

    
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 [55]:

    
va.set_block_size(10)        #set the block size
va.vizarray(checkerboard(20))#makes the checkerboard









    Out[55]:



In [56]:

    
assert True

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



In [57]:

    
va.set_block_size(5)
va.vizarray(checkerboard(27))#same as above









    Out[57]:



In [58]:

    
assert True