Question

Python REALLY NEED HELP !!!!!!!!!

[10pts] Write the class Vector that supports the basic vector operations. Such operations are addition (+) and subtraction (-) of vectors of the same length, dot product (*) and multiplication (*) of a vector by a scalar. All methods must return (not print) the result. Your class should also support the rich comparison for equality (==)

• - You must use the special methods for those 4 operators in order to override their behavior

• - You will need other special methods to achieve a legible object representation.

• - Dot product and multiplication by scalar use the same operator, so you must check the type

  of the object in order to decide which operation you have to perform

• - For addition and subtraction, you must check that vectors have the same length

• - The dot product results in a scalar, not a Vector

• - The rest of the methods must return a Vector object (not a string with the word Vector)

• - Test your code, this is how you ensure you get the most credit out of your work!!

• - When returning error messages, make sure your string contains the word ‘error’

• - Check the doctest for object behavior examples. Vector size is variable

• - Hint: Section 3.3.8. Emulating numeric types in

  https://docs.python.org/3/reference/datamodel.html#emulating-numeric-types

  Deliverables:

class Vector:

'''

>>> Vector([1,2])+Vector([5])

'Error - Invalid dimensions'

>>> Vector([1,2])+Vector([5,2])

Vector([6, 4])

>>> Vector([1,2])-Vector([5,2])

Vector([-4, 0])

>>> Vector([1,2])*Vector([5,2])

9

>>> x=Vector([2,4,6])

>>> y=Vector([2,4,6])

>>> c=x+y

>>> type(c)

<class 'LAB6.Vector'>

>>> print(c)

Vector([4, 8, 12])

>>> x==y

True

>>> x-Vector([1,2])

'Error - Invalid dimensions'

>>> x+5

'Error - Invalid operation'

>>> x*y

56

>>> x*5

Vector([10, 20, 30])

>>> 5*x

Vector([10, 20, 30])

'''

def __init__(self, vector_list):

self.vector = vector_list

# --- Your code starts here

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

#code

class Vector:

    '''

    >>> Vector([1,2])+Vector([5])

    'Error - Invalid dimensions'

    >>> Vector([1,2])+Vector([5,2])

    Vector([6, 4])

    >>> Vector([1,2])-Vector([5,2])

    Vector([-4, 0])

    >>> Vector([1,2])*Vector([5,2])

    9

    >>> x=Vector([2,4,6])

    >>> y=Vector([2,4,6])

    >>> c=x+y

    >>> type(c)

    <class 'LAB6.Vector'>

    >>> print(c)

    Vector([4, 8, 12])

    >>> x==y

    True

    >>> x-Vector([1,2])

    'Error - Invalid dimensions'

    >>> x+5

    'Error - Invalid operation'

    >>> x*y

    56

    >>> x*5

    Vector([10, 20, 30])

    >>> 5*x

    Vector([10, 20, 30])

    '''

    def __init__(self, vector_list):

        self.vector = vector_list

    #returns the length of underlying list as the length of vector

    def __len__(self):

        return len(self.vector)

    #returns a string containing vector contents

    def __repr__(self):

        return 'Vector('+repr(self.vector)+')'

    #adds two vectors (+ operator)

    def __add__(self, other):

        if type(other)!=Vector:

            #invalid operand

            return 'Error - Invalid operation'

        elif len(self)==len(other):

            #same length, creating an empty list

            res=[]

            #adding corresponding elements of this vector and other, appending to res

            for i in range(len(self)):

                res.append(self.vector[i]+other.vector[i])

            return Vector(res) #creating a Vector with values in res, and returns it

        return 'Error - Invalid dimensions' #invalid lengths

    #subtracts two vectors (- operator)

    def __sub__(self, other):

        if type(other)==Vector and len(self)==len(other):

            res=[]

            for i in range(len(self)):

                res.append(self.vector[i]-other.vector[i])

            return Vector(res)

        return 'Error - Invalid dimensions'

    #multiplies two vectors or finds scalar product based on type of other

    def __mul__(self, other):

        #checking if other type is int

        if type(other)==int:

            res=[]

            #returning scalar product

            for i in self.vector:

                res.append(i*other)

            return Vector(res)

        elif type(other)==Vector:

            #returning dot product if lengths are same

            if len(self)==len(other):

                dot_product=0

                for i in range(len(self)):

                    dot_product+=(self.vector[i]*other.vector[i])

                return dot_product

            else:

                return 'Error - Invalid dimensions'#invalid lengths

        else:

            return 'Error - Invalid operation' #invalid other type

    #same as multiplication, but calls when this vector object is in right side of

    #the * operator (example: vector*5 is __mul__, 5*vector is __rmul__)

    def __rmul__(self, other):

        return self.__mul__(other)

    #compares two vectors

    def __eq__(self, other):

        if type(other)==Vector:

            if len(self)!=len(other):

                #lengths mismatch

                return False

            for i in range(len(self)):

                if self.vector[i]!=other.vector[i]:

                    return False #elements mismatch

            return True #all elements checks out

        return False #type mismatch

#output (of doctest)