dot product in python code example

Example 1: python dictionary dot product

dot_product = sum(dict_1[key]*dict_2.get(key, 0) for key in dict_1)

Example 2: dot product python

A = [1,2,3,4,5,6]
B = [2,2,2,2,2,2]

# with numpy
import numpy as np
np.dot(A,B) # 42
np.sum(np.multiply(A,B)) # 42
#Python 3.5 has an explicit operator @ for the dot product
np.array(A)@np.array(B)# 42
# without numpy
sum([A[i]*B[i] for i in range(len(B))]) # 42

Example 3: numpy.dot

>>> a = [[1, 0], [0, 1]]
>>> b = [[4, 1], [2, 2]]
>>> np.dot(a, b)
array([[4, 1],
       [2, 2]])