In [1]:
import numpy as np
Create a class to represent vectors of arbitrary length and which is initialised with a list of values, e.g.:
x = MyVector([0, 2, 4])
Equip the class with methods that:
Test your implementation using two vectors of length 3. To help you get started, a skeleton of the class is provided below. Don't forget to use self where necessary.
In [2]:
class MyVector:
def __init__(self, x):
self.x = x
# Return length of vector
def size(self):
return len(self.x)
# This allows access by index, e.g. y[2]
def __getitem__(self, index):
return self.x[index]
# Return norm of vector
def norm(self):
squared_norm = 0
for el in self.x:
squared_norm += el*el
return np.sqrt(squared_norm)
# Return dot product of vector with another vector
def dot(self, other):
# Check if vector have the same length
if self.size() == other.size():
# Initialize product
prod = 0
# Add the product element by element to the total
for i in range(self.size()):
prod += self[i]*other[i]
else:
raise ValueError('Vector must be of the same length')
return prod
In [3]:
# Test cases
x = MyVector([3, 4, 0])
y = MyVector([1, 2, 6])
z = MyVector([1, 2])
print(x.size()) # 3
print(y.size()) # 3
print(x.norm()) # 5
print(y.norm()) # square root of 41
print(x.dot(y)) # 11
print(x.dot(z)) # Error
age' that returns the age of the studentEquip your class with the method '__repr__' such using print on a student record displays with the format
Surname: Bloggs, Forename: Andrea, College: ChurchillEquip your class with the method __lt__(self, other) so that a list of record entries can be sorted by
(surname, forename). Create a list of entries and test the sorting. Make sure you have two entries with the same
surname.
Hint: To get the current year:
In [4]:
import datetime
year = datetime.date.today().year
print(year)
In [5]:
class Students:
# We have 6 attributes, CRSid is optional (default value set to None)
def __init__(self, surname, forename, birthYear, triposYear, college, CRSid = None):
self.surname = surname
self.forename = forename
self.birthYear = birthYear
self.triposYear = triposYear
self.college = college
self.CRSid = CRSid
def __repr__(self):
"Print the student in the format Surname: surname, Forename: forename, College: college"
return 'Surname: {}, Forename: {}, College: {}'.format(self.surname, self.forename, self.college)
def age(self):
"Return the age of the student subtracting the year of birth from the current year"
return datetime.date.today().year - self.birthYear
def __lt__(self, other):
"""Return true if a student's surname is before (in alphabetical order) another student's surname;
if the surnames are equal do the same with the forenames"""
if self.surname == other.surname:
return self.forename < other.forename
else:
return self.surname < other.surname
In [6]:
# Test cases
stud0 = Students('Bella' ,'Zio', 1987, 2011, 'Università degli Studi di Torino')
stud1 = Students('Nano' ,'Gongolo', 1985, 2008, 'Università degli Studi di Torino')
stud2 = Students('Nano' ,'Dotto', 1984, 2008, 'Università degli Studi di Torino')
stud3 = Students('Casto' ,'Immanuel', 1988, 2011, 'Università degli Studi di Torino')
stud4 = Students('Ciavarro' ,'Massimo', 1983, 2006, 'Università degli Studi di Torino')
print(stud0)
print(stud0.age()) # 30
print(stud0 < stud1) # True
print(stud1 < stud0) # False
print(stud2 < stud1) # True
students_list = [stud0, stud1, stud2, stud3, stud4]
print('List:')
print(students_list)
print('Sorted list:')
students_list.sort()
print(students_list)