Numpy Exercise 1

Imports



In [90]:

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



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import antipackage
import github.ellisonbg.misc.vizarray as va

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 [122]:

    
def checkerboard(size):
    """Return a 2d checkboard of 0.0 and 1.0 as a NumPy array"""
    a=np.zeros((size,size))
    a[::2,::2]=1.0
    a[1::2,1::2]=1.0
    return a

raise NotImplementedError()









    



---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
<ipython-input-122-76cac979b60f> in <module>()
      6     return a
      7 
----> 8 raise NotImplementedError()

NotImplementedError:



In [123]:

    
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 [124]:

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









    Out[124]:



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assert True

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



In [125]:

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









    Out[125]:



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assert True