在 Python 中使用列表内涵语言创建一个词典

Question

I like the Python list comprehension syntax.

Can it be used to create dictionaries too? For example, by iterating over pairs of keys and values:

mydict = {(k,v) for (k,v) in blah blah blah}  # doesn't work

转载于:https://stackoverflow.com/questions/1747817/create-a-dictionary-with-list-comprehension-in-python

Answer 1

In Python 2.6 and earlier, the dict constructor can receive an iterable of key/value pairs:

d = dict((key, value) for (key, value) in iterable)

From Python 2.7 and 3 onwards, you can just use the dict comprehension syntax directly:

d = {key: value for (key, value) in iterable}

Of course, you can use the iterable in any way you want (tuples and lists literals, generator comprehensions, list comprehensions, generator functions, functional composition... feel creative) as long as each element is an iterable itself of two elements:

d = {value: foo(value) for value in sequence if bar(value)}

def key_value_gen(k):
   yield chr(k+65)
   yield chr((k+13)%26+65)
d = dict(map(key_value_gen, range(26)))