Question

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?

Answer 1

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().