The following little program needs some documentation and some tests. Since you didn't write it, I'll tell you what it's supposed to do. You'll need to document it. Feel free to test for additional exceptions if you have time but start with it as it is.
The point of the program is to compute the $L_{2}$ norm of a vector $v$. A second argument, if provided, will be interpreted as a vector of weights. The second argument must have the same length as the input vector.
NOTE: The input type of the vectors for this program should be a list of numbers.
As a reminder, the weighted $L_2$ norm of a vector $v$ is given by \begin{align*} \|v\|_{W} = \sqrt{\sum_{i=1}^{N}{\left(w_{i}v_{i}\right)^2}} \end{align*} where $N$ is the length of the vector $v$, $v_{i}$ is the i-th component of the vector $v$ and $w_{i}$ is the i-th component of the weight vector.
You must write the documentation and a decent test suite. Try to include some doctests as well!
Next, use the pytest module to run the doctests and unit tests and to assess the code coverage.
If you don't already have pytest, you can install it using pip install pytest. If you have trouble installing, here's the website: pytest installation.
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import numpy as np
def L2(v, *args):
"""Returns the norm of a vector v
INPUTS
======
v: list of float, vector
args:list of float, weight vector
RETURNS
======
norm: float
if the dimension of w and v is not the same, an error is raised
EXAMPLES
>>L2([1,1,1,1,1],[1,2,3,4,5])
7.416198487095663
"""
======
"""
s = 0.0 # Initialize sum
if len(args) == 0: # No weight vector
for vi in v:
s += vi * vi
else: # Weight vector present
w = args[0] # Get the weight vector
if (len(w) != len(v)): # Check lengths of lists
raise ValueError("Length of list of weights must match length of target list.")
for i, vi in enumerate(v):
s += w[i] * w[i] * vi * vi
return np.sqrt(s)
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L2([1,1,1,1,1],[1,2,3,4,5])
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import doctest
doctest.testmod(verbose=True)
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%%file L2.py
import numpy as np
def vector_len(v, *args):
"""Returns the norm of a vector v
INPUTS
======
v: list of float, vector
args:list of float, weight vector
RETURNS
======
norm: float
if the dimension of w and v is not the same, an error is raised
EXAMPLES
>>L2([1,1,1,1,1],[1,2,3,4,5])
7.416198487095663
"""
s = 0.0 # Initialize sum
if len(args) == 0: # No weight vector
for vi in v:
s += vi * vi
else: # Weight vector present
w = args[0] # Get the weight vector
if (len(w) != len(v)): # Check lengths of lists
raise ValueError("Length of list of weights must match length of target list.")
for i, vi in enumerate(v):
s += w[i] * w[i] * vi * vi
return np.sqrt(s)
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L2([1,1,1,1,1])
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%%file test_L2.py
import L2
def test_L2_result():
assert L2.vector_len([1,1,1,1,1],[1,2,3,4,5])==7.416198487095663
def test_L2_no_weight():
assert L2.vector_len([1,1,1,1,1])==2.2360679774997898
def test_L2_dimensions():
try:
L2.vector_len([1,1,1,1,1,1],[1,2,3])
except ValueError as err:
assert(type(err)==ValueError)
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!pytest --cov
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!pytest --cov --cov-report term-missing
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