CODEWITHSUNDEEP
pythondictionaryrandom
manxing
manxing

Reputation: 3305

How to randomly choose multiple keys and its value in a dictionary

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?

Upvotes: 31

Views: 52602

Answers (4)

Deepak Sharma
Deepak Sharma

Reputation: 1739

Simply

import random
mydict = {"a":"its a", "b":"its b"}
random.sample(mydict.items(), 1)

# [('b', 'its b')]
# or
# [('a', 'its a')]

Upvotes: 1

jss367
jss367

Reputation: 5381

If you wanted to return a dictionary, you could use a dictionary comprehension instead of the list comprehension in Sven Marnach's answer like so:

d = dict.fromkeys(range(100))
keys = random.sample(d.keys(), 10)
sample_d = {k: d[k] for k in keys}

Upvotes: 3

Gromph
Gromph

Reputation: 163

I have work on this problem,

import random

def random_a_dict_and_sample_it( a_dictionary , a_number ): 
    _ = {}
    for k1 in random.sample( list( a_dictionary.keys() ) , a_number ):
        _[ k1 ] = a_dictionary[ k1 ]
    return _

In your case:

user_dict = random_a_dict_and_sample_it( user_dict , 2 )

Upvotes: 1

Sven Marnach
Sven Marnach

Reputation: 601599

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().

Upvotes: 49

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