例如，列表。
l1 = [1,5,7] 我如何检查它的方法？
（例如，l1.append）
或字符串...... string.lower（
答案 0 :(得分：21)
您可以使用dir获取任何对象的方法列表。这在交互式提示中非常有用：
>>> dir(l1)
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__delslice__', '__doc__', '__eq__',
'__ge__', '__getattribute__', '__getitem__', '__getslice__', '__gt__', '__hash__', '__iadd__', '__imul__',
'__init__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__',
'__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__setslice__',
'__str__', 'append', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
有趣的方法通常是不以下划线开头的方法。如果您愿意，可以编写自己的dir版本，忽略以下划线开头的名称：
>>> mydir = lambda a:[x for x in dir(a) if not x.startswith('_')]
>>> mydir([])
['append', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
答案 1 :(得分：4)
您可能希望查看getmembers模块中的inspect函数
In [1]: import inspect
In [2]: inspect?
Type: module
Base Class: <type 'module'>
String Form: <module 'inspect' from '/usr/lib/python2.6/inspect.pyc'>
Namespace: Interactive
File: /usr/lib/python2.6/inspect.py
Docstring:
Get useful information from live Python objects.
This module encapsulates the interface provided by the internal special
attributes (func_*, co_*, im_*, tb_*, etc.) in a friendlier fashion.
It also provides some help for examining source code and class layout.
Here are some of the useful functions provided by this module:
ismodule(), isclass(), ismethod(), isfunction(), isgeneratorfunction(),
isgenerator(), istraceback(), isframe(), iscode(), isbuiltin(),
isroutine() - check object types
getmembers() - get members of an object that satisfy a given condition
getfile(), getsourcefile(), getsource() - find an object's source code
getdoc(), getcomments() - get documentation on an object
getmodule() - determine the module that an object came from
getclasstree() - arrange classes so as to represent their hierarchy
getargspec(), getargvalues() - get info about function arguments
formatargspec(), formatargvalues() - format an argument spec
getouterframes(), getinnerframes() - get info about frames
currentframe() - get the current stack frame
stack(), trace() - get info about frames on the stack or in a traceback
In [3]: l1=[1,5,7]
In [4]: inspect.getmembers(l1)
Out[4]:
[('__add__', <method-wrapper '__add__' of list object at 0xa38716c>),
('__class__', <type 'list'>),
('__contains__', <method-wrapper '__contains__' of list object at 0xa38716c>),
('__delattr__', <method-wrapper '__delattr__' of list object at 0xa38716c>),
('__delitem__', <method-wrapper '__delitem__' of list object at 0xa38716c>),
('__delslice__', <method-wrapper '__delslice__' of list object at 0xa38716c>),
('__doc__',
"list() -> new list\nlist(sequence) -> new list initialized from sequence's items"),
('__eq__', <method-wrapper '__eq__' of list object at 0xa38716c>),
('__format__', <built-in method __format__ of list object at 0xa38716c>),
('__ge__', <method-wrapper '__ge__' of list object at 0xa38716c>),
('__getattribute__',
<method-wrapper '__getattribute__' of list object at 0xa38716c>),
('__getitem__', <built-in method __getitem__ of list object at 0xa38716c>),
('__getslice__', <method-wrapper '__getslice__' of list object at 0xa38716c>),
('__gt__', <method-wrapper '__gt__' of list object at 0xa38716c>),
('__hash__', None),
('__iadd__', <method-wrapper '__iadd__' of list object at 0xa38716c>),
('__imul__', <method-wrapper '__imul__' of list object at 0xa38716c>),
('__init__', <method-wrapper '__init__' of list object at 0xa38716c>),
('__iter__', <method-wrapper '__iter__' of list object at 0xa38716c>),
('__le__', <method-wrapper '__le__' of list object at 0xa38716c>),
('__len__', <method-wrapper '__len__' of list object at 0xa38716c>),
('__lt__', <method-wrapper '__lt__' of list object at 0xa38716c>),
('__mul__', <method-wrapper '__mul__' of list object at 0xa38716c>),
('__ne__', <method-wrapper '__ne__' of list object at 0xa38716c>),
('__new__', <built-in method __new__ of type object at 0x822be40>),
('__reduce__', <built-in method __reduce__ of list object at 0xa38716c>),
('__reduce_ex__',
<built-in method __reduce_ex__ of list object at 0xa38716c>),
('__repr__', <method-wrapper '__repr__' of list object at 0xa38716c>),
('__reversed__', <built-in method __reversed__ of list object at 0xa38716c>),
('__rmul__', <method-wrapper '__rmul__' of list object at 0xa38716c>),
('__setattr__', <method-wrapper '__setattr__' of list object at 0xa38716c>),
('__setitem__', <method-wrapper '__setitem__' of list object at 0xa38716c>),
('__setslice__', <method-wrapper '__setslice__' of list object at 0xa38716c>),
('__sizeof__', <built-in method __sizeof__ of list object at 0xa38716c>),
('__str__', <method-wrapper '__str__' of list object at 0xa38716c>),
('__subclasshook__',
<built-in method __subclasshook__ of type object at 0x822be40>),
('append', <built-in method append of list object at 0xa38716c>),
('count', <built-in method count of list object at 0xa38716c>),
('extend', <built-in method extend of list object at 0xa38716c>),
('index', <built-in method index of list object at 0xa38716c>),
('insert', <built-in method insert of list object at 0xa38716c>),
('pop', <built-in method pop of list object at 0xa38716c>),
('remove', <built-in method remove of list object at 0xa38716c>),
('reverse', <built-in method reverse of list object at 0xa38716c>),
('sort', <built-in method sort of list object at 0xa38716c>)]
答案 2 :(得分：2)
Interactive Python具有help功能，可以与任何东西一起使用：
>>> help(list)
Help on class list in module __builtin__:
class list(object)
| list() -> new list
| list(sequence) -> new list initialized from sequence´s items
|
| Methods defined here:
|
| __add__(...)
| x.__add__(y) <==> x+y
|
| __contains__(...)
| x.__contains__(y) <==> y in x
|
| __delitem__(...)
| x.__delitem__(y) <==> del x[y]
|
| __delslice__(...)
| x.__delslice__(i, j) <==> del x[i:j]
|
| Use of negative indices is not supported.
|
| __eq__(...)
| x.__eq__(y) <==> x==y
|
| __ge__(...)
| x.__ge__(y) <==> x>=y
|
| __getattribute__(...)
| x.__getattribute__('name') <==> x.name
|
| __getitem__(...)
| x.__getitem__(y) <==> x[y]
|
| __getslice__(...)
| x.__getslice__(i, j) <==> x[i:j]
|
| Use of negative indices is not supported.
|
| __gt__(...)
| x.__gt__(y) <==> x>y
|
| __iadd__(...)
| x.__iadd__(y) <==> x+=y
|
| __imul__(...)
| x.__imul__(y) <==> x*=y
|
| __init__(...)
| x.__init__(...) initializes x; see x.__class__.__doc__ for signature
|
| __iter__(...)
| x.__iter__() <==> iter(x)
|
| __le__(...)
| x.__le__(y) <==> x<=y
|
| __len__(...)
| x.__len__() <==> len(x)
|
| __lt__(...)
| x.__lt__(y) <==> x<y
|
| __mul__(...)
| x.__mul__(n) <==> x*n
|
| __ne__(...)
| x.__ne__(y) <==> x!=y
|
| __repr__(...)
| x.__repr__() <==> repr(x)
|
| __reversed__(...)
| L.__reversed__() -- return a reverse iterator over the list
|
| __rmul__(...)
| x.__rmul__(n) <==> n*x
|
| __setitem__(...)
| x.__setitem__(i, y) <==> x[i]=y
|
| __setslice__(...)
| x.__setslice__(i, j, y) <==> x[i:j]=y
|
| Use of negative indices is not supported.
|
| __sizeof__(...)
| L.__sizeof__() -- size of L in memory, in bytes
|
| append(...)
| L.append(object) -- append object to end
|
| count(...)
| L.count(value) -> integer -- return number of occurrences of value
|
| extend(...)
| L.extend(iterable) -- extend list by appending elements from the iterable
|
| index(...)
| L.index(value, [start, [stop]]) -> integer -- return first index of value.
| Raises ValueError if the value is not present.
|
| insert(...)
| L.insert(index, object) -- insert object before index
|
| pop(...)
| L.pop([index]) -> item -- remove and return item at index (default last).
| Raises IndexError if list is empty or index is out of range.
|
| remove(...)
| L.remove(value) -- remove first occurrence of value.
| Raises ValueError if the value is not present.
|
| reverse(...)
| L.reverse() -- reverse *IN PLACE*
|
| sort(...)
| L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;
| cmp(x, y) -> -1, 0, 1
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| __hash__ = None
|
| __new__ = <built-in method __new__ of type object at 0x1E1CF100>
| T.__new__(S, ...) -> a new object with type S, a subtype of T
答案 3 :(得分：1)
如果您安装IPython，则可以执行此操作：
% ipython
Python 2.6.4 (r264:75706, Nov 2 2009, 14:38:03)
Type "copyright", "credits" or "license" for more information.
IPython 0.10 -- An enhanced Interactive Python.
? -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help -> Python's own help system.
object? -> Details about 'object'. ?object also works, ?? prints more.
In [1]: l1=[1,5,7]
In [2]: l1.
l1.__add__ l1.__getslice__ l1.__new__ l1.append
l1.__class__ l1.__gt__ l1.__reduce__ l1.count
l1.__contains__ l1.__hash__ l1.__reduce_ex__ l1.extend
l1.__delattr__ l1.__iadd__ l1.__repr__ l1.index
l1.__delitem__ l1.__imul__ l1.__reversed__ l1.insert
l1.__delslice__ l1.__init__ l1.__rmul__ l1.pop
l1.__doc__ l1.__iter__ l1.__setattr__ l1.remove
l1.__eq__ l1.__le__ l1.__setitem__ l1.reverse
l1.__format__ l1.__len__ l1.__setslice__ l1.sort
l1.__ge__ l1.__lt__ l1.__sizeof__
l1.__getattribute__ l1.__mul__ l1.__str__
l1.__getitem__ l1.__ne__ l1.__subclasshook__
In [2]: l1.
在最后一行，键入对象名称，句点，然后按Tab键。然后IPython列出对象的所有属性。
我发现IPython是探索对象属性的宝贵工具。使用它比标准的Python交互式提示更方便。在其他漂亮的东西中，在对象后面添加一个问号会给你一个doc字符串：
In [6]: d.update?
Type: builtin_function_or_method
Base Class: <type 'builtin_function_or_method'>
String Form: <built-in method update of dict object at 0xa3c024c>
Namespace: Interactive
Docstring:
D.update(E, **F) -> None. Update D from dict/iterable E and F.
If E has a .keys() method, does: for k in E: D[k] = E[k]
If E lacks .keys() method, does: for (k, v) in E: D[k] = v
In either case, this is followed by: for k in F: D[k] = F[k]
并且，如果可用，两个问号将为您提供源代码：
In [18]: np.sum??
Type: function
Base Class: <type 'function'>
String Form: <function sum at 0x9c501ec>
Namespace: Interactive
File: /usr/lib/python2.6/dist-packages/numpy/core/fromnumeric.py
Definition: np.sum(a, axis=None, dtype=None, out=None)
Source:
def sum(a, axis=None, dtype=None, out=None):
...
if isinstance(a, _gentype):
res = _sum_(a)
if out is not None:
out[...] = res
return out
return res
try:
sum = a.sum
except AttributeError:
return _wrapit(a, 'sum', axis, dtype, out)
return sum(axis, dtype, out)
答案 4 :(得分：1)
实际上，列表实例的所有成员都是方法。如果不是这样，你可以使用它：
l1 = [1, 5 , 7]
print [name for name in dir(l1) if type(getattr(l1, name) == type(l1.append))]
这将排除不是方法的成员。
答案 5 :(得分：0)
如果对象（通常可能是一个模块）使用dir有很多方法或属性，或者ipython的TAB完成可以变得复杂以跟踪。
在这种情况下，我使用过滤器，如下例所示：
filter(lambda s: 'sin' in s.lower(), dir(numpy))
导致
['arcsin',
'arcsinh',
'csingle',
'isinf',
'isposinf',
'sin',
'sinc',
'single',
'singlecomplex',
'sinh']
我觉得探索未知对象非常方便，我希望它们必须有一个方法（或属性）作为其名称的一部分。