如何从python中的字典中获取随机值

How can I get a random pair from a dict? I’m making a game where you need to guess a capital of a country and I need questions to appear randomly.

The dict looks like {'VENEZUELA':'CARACAS'}

How can I do this?

One way would be:

import random
d = {'VENEZUELA':'CARACAS', 'CANADA':'OTTAWA'}
random.choice(list(d.values()))

EDIT: The question was changed a couple years after the original post, and now asks for a pair, rather than a single item. The final line should now be:

country, capital = random.choice(list(d.items()))

I wrote this trying to solve the same problem:

https://github.com/robtandy/randomdict

It has O(1) random access to keys, values, and items.

Try this:

import random
a = dict(....) # a is some dictionary
random_key = random.sample(a, 1)[0]

This definitely works.

If you don’t want to use the random module, you can also try popitem():

>> d = {'a': 1, 'b': 5, 'c': 7}
>>> d.popitem()
('a', 1)
>>> d
{'c': 7, 'b': 5}
>>> d.popitem()
('c', 7)

Since the dict doesn’t preserve order, by using popitem you get items in an arbitrary (but not strictly random) order from it.

Also keep in mind that popitem removes the key-value pair from dictionary, as stated in the docs.

popitem() is useful to destructively iterate over a dictionary

>>> import random
>>> d = dict(Venezuela = 1, Spain = 2, USA = 3, Italy = 4)
>>> random.choice(d.keys())
'Venezuela'
>>> random.choice(d.keys())
'USA'

By calling random.choice on the keys of the dictionary (the countries).

This works in Python 2 and Python 3:

A random key:

random.choice(list(d.keys()))

A random value

random.choice(list(d.values()))

A random key and value

random.choice(list(d.items()))

If you don’t want to use random.choice() you can try this way:

>>> list(myDictionary)[i]
'VENEZUELA'
>>> myDictionary = {'VENEZUELA':'CARACAS', 'IRAN' : 'TEHRAN'}
>>> import random
>>> i = random.randint(0, len(myDictionary) - 1)
>>> myDictionary[list(myDictionary)[i]]
'TEHRAN'
>>> list(myDictionary)[i]
'IRAN'

Since the original post wanted the pair:

import random
d = {'VENEZUELA':'CARACAS', 'CANADA':'TORONTO'}
country, capital = random.choice(list(d.items()))

(python 3 style)

Since this is homework:

Check out which will select and return a random element from an list. You can get a list of dictionary keys with dict.keys() and a list of dictionary values with dict.values().

I am assuming that you are making a quiz kind of application. For this kind of application I have written a function which is as follows:

def shuffle(q):
"""
The input of the function will 
be the dictionary of the question
and answers. The output will
be a random question with answer
"""
selected_keys = []
i = 0
while i < len(q):
    current_selection = random.choice(q.keys())
    if current_selection not in selected_keys:
        selected_keys.append(current_selection)
        i = i+1
        print(current_selection+'? '+str(q[current_selection]))

If I will give the input of questions = {'VENEZUELA':'CARACAS', 'CANADA':'TORONTO'} and call the function shuffle(questions) Then the output will be as follows:

VENEZUELA? CARACAS
CANADA? TORONTO

You can extend this further more by shuffling the options also

Try this (using random.choice from items)

import random

a={ "str" : "sda" , "number" : 123, 55 : "num"}
random.choice(list(a.items()))
#  ('str', 'sda')
random.choice(list(a.items()))[1] # getting a value
#  'num'

With modern versions of Python(since 3), the objects returned by methods dict.keys(), dict.values() and dict.items() are view objects*. And hey can be iterated, so using directly random.choice is not possible as now they are not a list or set.

One option is to use list comprehension to do the job with random.choice:

import random

colors = {
    'purple': '#7A4198',
    'turquoise':'#9ACBC9',
    'orange': '#EF5C35',
    'blue': '#19457D',
    'green': '#5AF9B5',
    'red': ' #E04160',
    'yellow': '#F9F985'
}

color=random.choice([hex_color for color_value in colors.values()]

print(f'The new color is: {color}')

References:

• *Python 3.8: Standard Library Documentation – Built-in types: Dictionary view objects
• Python 3.8: Data Structures – List Comprehensions:

b = { 'video':0, 'music':23,"picture":12 } 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('picture', 12) 
random.choice(tuple(b.items())) ('video', 0) 

I found this post by looking for a rather comparable solution. For picking multiple elements out of a dict, this can be used:

idx_picks = np.random.choice(len(d), num_of_picks, replace=False) #(Don't pick the same element twice)
result = dict ()
c_keys = [d.keys()] #not so efficient - unfortunately .keys() returns a non-indexable object because dicts are unordered
for i in idx_picks:
    result[c_keys[i]] = d[i]