Numpy Exercise 1

Imports


In [20]:
import numpy as np
%matplotlib inline
import matplotlib.pyplot as plt
import seaborn as sns

In [21]:
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 [28]:
def checkerboard(size):
    a = np.zeros((size,size))
    a[0::2,::2] = 1
    a[1::2,1::2] = 1
    return a

In [29]:
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 [32]:
va.set_block_size(10)
va.enable()

In [33]:
va.vizarray(checkerboard(20))


Out[33]:

In [34]:
assert True

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


In [35]:
va.set_block_size(5)
va.vizarray(checkerboard(27))


Out[35]:

In [36]:
assert True

Success!