帶有元組列表的嵌套字典作為來自python中DATA文件的值

Question

請幫忙。 我有一個包含 4 列（userid、movieid、score、timestamp）的數據文件，如下所示：

196 242 3   881250949
186 302 3   891717742
22  377 1   878887116
196 51  2   880606923
62  257 2   879372434

我正在嘗試創建一個看起來像這樣的嵌套字典：

用戶 = {'196': [('242', '3'), ('51', '2')], '186': ['302','3'] ...}

我的代碼只為每個用戶 ID 選取一個元組 (movieid, score)：

def create_users_dict():
    try:
        users = {}
        for line in open('u.data'):
            (id, movieid, rating, timestamp) = line.split('\t')[0:4]
            users[id] = (movieid, rating)
    except IOError as ioerr:
        print('There is an error with the file:' + str(ioerr))
    return users
users = create_users_dict()

用戶 = {'196': ('51', '2'), '186': ('302', '3')...}

Answer 1

使用setdefault ：

def create_users_dict():
    try:
        users = {}
        for line in open('u.data'):
            uid, movie_id, rating, timestamp = line.split()
            users.setdefault(uid, []).append((movie_id, rating))
        return users
    except IOError as ioerr:
        print('There is an error with the file:' + str(ioerr))
users = create_users_dict()

print(users)

輸出

{'196': [('242', '3'), ('51', '2')], '62': [('257', '2')], '186': [('302', '3')], '22': [('377', '1')]}

一種可能的替代方法是檢查鍵 ( uid ) 是否在字典中，以防丟失用空列表初始化值，然后簡單地追加。

def create_users_dict():
    try:
        users = {}
        for line in open('u.dat'):
            uid, movie_id, rating, timestamp = line.split()
            if uid not in users:
                users[uid] = []
            users[uid].append((movie_id, rating))
        return users
    except IOError as ioerr:
        print('There is an error with the file:' + str(ioerr))

作為旁注，您不應該使用id作為名稱，因為它隱藏了內置函數id 。