用两个列表中的随机元素创建字典列表-python

Question

Is there a way in python to perform randomization between two lists within a list and have a dictionary returned?

For example, from:

[[1,2,3,4], ['a','b','c','d']]

to:

[{3:'a'}, {1:'d'}, {2:'c'}, {4:'b'}]

What's the best way to achieve this? Using a list comprehension? My two lists are actually very large, so I'm wondering whether there's a more efficient alternative.

Answer 1

import random
keys, values = [[1,2,3,4], ['a','b','c','d']]
random.shuffle(values)
result =  [{k:v} for k, v in zip(keys, values)]

produces a list such as:

In [7]: result
Out[7]: [{1: 'd'}, {2: 'b'}, {3: 'c'}, {4: 'a'}]

A more memory-efficient alternative would be to use an iterator:

import itertools as IT
result = ({k:v} for k, v in IT.izip(keys, values))

The larger question is why you would want a sequence of tiny dicts. Wouldn't it be more useful to have one dict, such as the one produced by Steven Rumbalski's answer?

Or, if you really do just want a randomized pairing, perhaps an iterator of tuples would suffice:

result = IT.izip(keys, values)

Answer 2

This creates a single dictionary rather than a list of single item dictionaries as your question requests. If you really want that, use unutbu's answer .

import random

a = [1,2,3,4]
b = ['a','b','c','d']

random.shuffle(a)
result = dict(zip(a, b))

If you cannot mutate your source lists:

dx = range(len(a))
random.shuffle(dx)
dict(zip((a[i] for i in dx), b))