dot_product = sum(dict_1[key]*dict_2.get(key, 0) for key in dict_1)
Here is what the above code is Doing:
1. We create a list of tuples, where each tuple is a key-value pair from dict_1.
2. We iterate over this list of tuples, and for each tuple we:
a. Get the key from the tuple.
b. Get the value from the tuple.
c. Get the value for the key from dict_2. If the key is not in dict_2, we get a default value of 0.
d. We multiply the two values together.
3. We sum up all of the products we just calculated.