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I have a dictionary like this:
user_dict = { user1: [(video1, 10),(video2,20),(video3,1)] user2: [(video1, 4),(video2,8),(video6,45)] ... user100: [(video1, 46),(video2,34),(video6,4)] } (video1,10) means (videoid, number of request) Now I want to randomly choose 10 users and do some calculation like
1. calculate number of videoid for each user. 2. sum up the number of requests for these 10 random users, etc then I need to increase the random number to 20, 30, 40 respectively
But "random.choice" can only choose one value at a time, right? how to choose multiple keys and the list following each key?
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To get a random value from a dictionary in Python, you can use the random module choice() function, list() function and dictionary values() function. If you want to get a random key from a dictionary, you can use the dictionary keys() function instead.
Python dictionary is not iterable. Hence it doesn't have index to be randomized. Instead collection of its keys is iterable and can be randomized by shuffle() function in random module.
In python, if we want a dictionary in which one key has multiple values, then we need to associate an object with each key as value. This value object should be capable of having various values inside it. We can either use a tuple or a list as a value in the dictionary to associate multiple values with a key.
Answer. No, each key in a dictionary should be unique. You can't have two keys with the same value. Attempting to use the same key again will just overwrite the previous value stored.
That's what random.sample() is for:
Return a k length list of unique elements chosen from the population sequence. Used for random sampling without replacement.
This can be used to choose the keys. The values can subsequently be retrieved by normal dictionary lookup:
>>> d = dict.fromkeys(range(100)) >>> keys = random.sample(list(d), 10) >>> keys [52, 3, 10, 92, 86, 42, 99, 73, 56, 23] >>> values = [d[k] for k in keys] Alternatively, you can directly sample from d.items().
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