如何检查python中的iterable实例？

Question

考虑这个例子？

p = [1,2,3,4], (1,2,3), set([1,2,3])]

而不是检查每种类型

for x in p:
   if isinstance(x, list):
      xxxxx
   elif isinstance(x, tuple):
      xxxxxx
   elif isinstance(x, set):
      xxxxxxx

以下是否有一些等价物:

for element in something:
  if isinstance(x, iterable):
      do something

Answer 1

您可以尝试使用模块中的IterableABC collections:

In [1]: import collections

In [2]: p = [[1,2,3,4], (1,2,3), set([1,2,3]), 'things', 123]

In [3]: for item in p:
   ...:     print isinstance(item, collections.Iterable)
   ...:     
True
True
True
True
False

Answer 2

您可以检查对象是否具有__iter__属性,以确保它是否可迭代.

a = [1, 2, 3]
b = {1, 2, 3}
c = (1, 2, 3)
d = {"a": 1}
f = "Welcome"
e = 1
print (hasattr(a, "__iter__"))
print (hasattr(b, "__iter__"))
print (hasattr(c, "__iter__"))
print (hasattr(d, "__iter__"))
print (hasattr(f, "__iter__") or isinstance(f, str))
print (hasattr(e, "__iter__"))

产量

True
True
True
True
True
False

注意:尽管Strings是可迭代的,但是在python 2中他们没有__iter__,但是在python 3中他们拥有它.所以,在python 2中你可能也想拥有 or isinstance(f, str)它