单个可迭代 `list(x)` 与 `[x]` 的列表有什么区别? [英] What is the difference between a list of a single iterable `list(x)` vs `[x]`?

问题描述

在创建列表对象时，

Python似乎在 [x] 和 list(x)之间进行区分，其中 x 是可迭代的.为什么会有这种差异?

 >>>a = [dict(a = 1)]>>>[{'a':1}]>>>一个=列表(dict(a = 1))>>>a = ['a'] 

虽然第一个表达式似乎可以按预期工作，但第二个表达式的工作方式更像是迭代dict:

 >>>l = []>>>对于{'a':1}中的e:l.append(e)>>>升>>>['一种'] 

解决方案

[x] 是一个包含 element x 的列表./p>

list(x)接受 x (必须已经可迭代！)并将其转换为列表.

 >>>[1]#列表文字[1]>>>['abc']#包含'abc'的列表['abc']>>>列表(1)#TypeError>>>list((1，))#列表构造函数[1]>>>list('abc')#字符串是可迭代的['a', 'b', 'c'] # 把字符串变成列表！ 

列表构造函数 list(...)-像python的所有内置集合类型(集合，列表，元组，collection.deque等)一样-可以采用单个可迭代参数并进行转换.

Python seems to differentiate between [x] and list(x) when making a list object, where x is an iterable. Why this difference?

>>> a = [dict(a = 1)]
>>> [{'a' : 1}]

>>> a = list(dict(a=1))
>>> a = ['a']

While the 1st expression seems to work as expected, the 2nd expression works more like iterating a dict this way:

>>> l = []
>>> for e in {'a' :1}:
        l.append(e)
>>> l
>>> ['a']

解决方案

[x] is a list containing the element x.

list(x) takes x (which must already be iterable!) and turns it into a list.

>>> [1]  # list literal
[1]
>>> ['abc']  # list containing 'abc'
['abc']
>>> list(1)
# TypeError
>>> list((1,))  # list constructor
[1]
>>> list('abc')  # strings are iterables
['a', 'b', 'c']  # turns string into list!

The list constructor list(...) - like all of python's built-in collection types (set, list, tuple, collections.deque, etc.) - can take a single iterable argument and convert it.

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