euclidean_score.py 文件源码

def euclidean_score(dataset, user1, user2):
    if user1 not in dataset:
        raise TypeError('User ' + user1 + ' not present in the dataset')

    if user2 not in dataset:
        raise TypeError('User ' + user2 + ' not present in the dataset')

    # Movies rated by both user1 and user2
    rated_by_both = {} 

    for item in dataset[user1]:
        if item in dataset[user2]:
            rated_by_both[item] = 1

    # If there are no common movies, the score is 0 
    if len(rated_by_both) == 0:
        return 0

    squared_differences = [] 

    for item in dataset[user1]:
        if item in dataset[user2]:
            squared_differences.append(np.square(dataset[user1][item] - dataset[user2][item]))

    return 1 / (1 + np.sqrt(np.sum(squared_differences)))