Coding the Matrix -3장 Vector(추가)

In [11]:

class Vec:

    def __init__(self, labels, function):

        self.D=labels

        self.f=function

v=Vec(['A', 'B', 'C'], {'A':1})

​

for d in v.D:

    if d in v.f:

        print(v.f[d])

​

def zero_vec(D):

    return Vec(D, {d:0 for d in D})

​

d={1,2,3,4,5,6,7,8}

dp = zero_vec(d)

print(dp)

1
<__main__.Vec object at 0x000000000492ABE0>

In [34]:

class Vec:

    def __init__(self, labels, function):

        self.D=labels

        self.f=function

v=Vec(['A', 'B', 'C'], {'A':1})

​

def setitem(v, d, val) :

    if d in v.D :

        v.f[d] = val

    else :

        print('out of range')

​

def getitem(v,d) :

    return v.f[d] if d in v.f else 0

​

setitem(v,'B',2)

setitem(v,'C',5)

​

print(v.D)

print(getitem(v, 'B'))

['A', 'B', 'C']
2

In [33]:

def scalar_mul(v, alpha) :

    return ([v[i]*alpha for i in range(len(v))])

v=[1,2,3,4,5,6]

print(scalar_mul(v, 3))

[3, 6, 9, 12, 15, 18]

In [55]:

def setitem(v, d, val) :

    if d in v.D :

        v.f[d] = val

    else :

        print('out of range')

​

def getitem(v,d) :

    return v.f[d] if d in v.f else 0

​

def scalar_mul(v, alpha) :

    return Vec(v.D, {d:alpha*getitem(v, d) for d in v.D})

def scalar_mul2(v, alpha) :

    return Vec(v.D, {d:alpha*value for d, value in v.f.items() })

v=Vec(['A', 'B','C'], {'A':1, 'B':2, 'C':3})

vp=scalar_mul2(v,3)

getitem(vp, 'B')

​

def add(u, v) :

    return Vec(u.D, {getitem(u,d) + getitem(v, d) for d in u.D})

add(v,vp)

add(v,vp).f

add(v,vp).D

​

Out[55]:

['A', 'B', 'C']

In [65]:

def dot_prod(v,w) :

    return (sum(v[i]*w[i] for i in range(len(v))))

def list_dot(u, v):

    return sum(i*j for (i,j) in zip(u,v))

v=[1.,2.,3.,4.,5.]

w=[1/5, 1/5, 1/5, 1/5,1/5]

print(dot_prod(v,w))

print(list_dot(v,w))

3.0
3.0