Python 字典
阿新 • • 發佈：2017-09-11
pre this 叠代 closed .get raise 清除 found python 
1、創建一個字典
>>> a = {‘name‘: ‘gm‘, ‘age‘: 18}
>>> a
{‘age‘: 18, ‘name‘: ‘gm‘}
2、查看字典
# 獲取字典a的值 >>> a {‘age‘: 18, ‘name‘: ‘gm‘} # 獲取特定key的值 >>> a.[‘name‘]‘gm‘ >>> a.[‘age‘]18
3、查看字典可以進行的操作
>>> dir(a) [‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__delitem__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__setattr__‘, ‘__setitem__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘clear‘, ‘copy‘, ‘fromkeys‘, ‘get‘, ‘items‘, ‘keys‘, ‘pop‘, ‘popitem‘, ‘setdefault‘, ‘update‘, ‘values‘]
class dict(object): """ dict() -> new empty dictionary dict(mapping) -> new dictionary initialized from a mapping object‘s (key, value) pairs dict(iterable) -> new dictionary initialized as if via: d = {} for k, v in iterable: d[k] = v dict(**kwargs) -> new dictionary initialized with the name=value pairs in the keyword argument list. For example: dict(one=1, two=2)dict""" def clear(self): # real signature unknown; restored from __doc__ """ 清除內容 """ """ D.clear() -> None. Remove all items from D. """ pass def copy(self): # real signature unknown; restored from __doc__ """ 淺拷貝 """ """ D.copy() -> a shallow copy of D """ pass @staticmethod # known case def fromkeys(S, v=None): # real signature unknown; restored from __doc__ """ dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v. v defaults to None. """ pass def get(self, k, d=None): # real signature unknown; restored from __doc__ """ 根據key獲取值，d是默認值 """ """ D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """ pass def has_key(self, k): # real signature unknown; restored from __doc__ """ 是否有key """ """ D.has_key(k) -> True if D has a key k, else False """ return False def items(self): # real signature unknown; restored from __doc__ """ 所有項的列表形式 """ """ D.items() -> list of D‘s (key, value) pairs, as 2-tuples """ return [] def iteritems(self): # real signature unknown; restored from __doc__ """ 項可叠代 """ """ D.iteritems() -> an iterator over the (key, value) items of D """ pass def iterkeys(self): # real signature unknown; restored from __doc__ """ key可叠代 """ """ D.iterkeys() -> an iterator over the keys of D """ pass def itervalues(self): # real signature unknown; restored from __doc__ """ value可叠代 """ """ D.itervalues() -> an iterator over the values of D """ pass def keys(self): # real signature unknown; restored from __doc__ """ 所有的key列表 """ """ D.keys() -> list of D‘s keys """ return [] def pop(self, k, d=None): # real signature unknown; restored from __doc__ """ 獲取並在字典中移除 """ """ D.pop(k[,d]) -> v, remove specified key and return the corresponding value. If key is not found, d is returned if given, otherwise KeyError is raised """ pass def popitem(self): # real signature unknown; restored from __doc__ """ 獲取並在字典中移除 """ """ D.popitem() -> (k, v), remove and return some (key, value) pair as a 2-tuple; but raise KeyError if D is empty. """ pass def setdefault(self, k, d=None): # real signature unknown; restored from __doc__ """ 如果key不存在，則創建，如果存在，則返回已存在的值且不修改 """ """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """ pass def update(self, E=None, **F): # known special case of dict.update """ 更新 {‘name‘:‘alex‘, ‘age‘: 18000} [(‘name‘,‘sbsbsb‘),] """ """ D.update([E, ]**F) -> None. Update D from dict/iterable E and F. If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and 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] """ pass def values(self): # real signature unknown; restored from __doc__ """ 所有的值 """ """ D.values() -> list of D‘s values """ return [] def viewitems(self): # real signature unknown; restored from __doc__ """ 所有項，只是將內容保存至view對象中 """ """ D.viewitems() -> a set-like object providing a view on D‘s items """ pass def viewkeys(self): # real signature unknown; restored from __doc__ """ D.viewkeys() -> a set-like object providing a view on D‘s keys """ pass def viewvalues(self): # real signature unknown; restored from __doc__ """ D.viewvalues() -> an object providing a view on D‘s values """ pass def __cmp__(self, y): # real signature unknown; restored from __doc__ """ x.__cmp__(y) <==> cmp(x,y) """ pass def __contains__(self, k): # real signature unknown; restored from __doc__ """ D.__contains__(k) -> True if D has a key k, else False """ return False def __delitem__(self, y): # real signature unknown; restored from __doc__ """ x.__delitem__(y) <==> del x[y] """ pass def __eq__(self, y): # real signature unknown; restored from __doc__ """ x.__eq__(y) <==> x==y """ pass def __getattribute__(self, name): # real signature unknown; restored from __doc__ """ x.__getattribute__(‘name‘) <==> x.name """ pass def __getitem__(self, y): # real signature unknown; restored from __doc__ """ x.__getitem__(y) <==> x[y] """ pass def __ge__(self, y): # real signature unknown; restored from __doc__ """ x.__ge__(y) <==> x>=y """ pass def __gt__(self, y): # real signature unknown; restored from __doc__ """ x.__gt__(y) <==> x>y """ pass def __init__(self, seq=None, **kwargs): # known special case of dict.__init__ """ dict() -> new empty dictionary dict(mapping) -> new dictionary initialized from a mapping object‘s (key, value) pairs dict(iterable) -> new dictionary initialized as if via: d = {} for k, v in iterable: d[k] = v dict(**kwargs) -> new dictionary initialized with the name=value pairs in the keyword argument list. For example: dict(one=1, two=2) # (copied from class doc) """ pass def __iter__(self): # real signature unknown; restored from __doc__ """ x.__iter__() <==> iter(x) """ pass def __len__(self): # real signature unknown; restored from __doc__ """ x.__len__() <==> len(x) """ pass def __le__(self, y): # real signature unknown; restored from __doc__ """ x.__le__(y) <==> x<=y """ pass def __lt__(self, y): # real signature unknown; restored from __doc__ """ x.__lt__(y) <==> x<y """ pass @staticmethod # known case of __new__ def __new__(S, *more): # real signature unknown; restored from __doc__ """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __ne__(self, y): # real signature unknown; restored from __doc__ """ x.__ne__(y) <==> x!=y """ pass def __repr__(self): # real signature unknown; restored from __doc__ """ x.__repr__() <==> repr(x) """ pass def __setitem__(self, i, y): # real signature unknown; restored from __doc__ """ x.__setitem__(i, y) <==> x[i]=y """ pass def __sizeof__(self): # real signature unknown; restored from __doc__ """ D.__sizeof__() -> size of D in memory, in bytes """ pass __hash__ = None
4、常用的字典操作
# 插入新的鍵值
>>> a {‘age‘: 18, ‘name‘: ‘gm‘} >>> a[‘job‘] = ‘運維‘ >>> a {‘age‘: 18, ‘job‘: ‘運維‘, ‘name‘: ‘gm‘}
# 修改字典某鍵的值 >>> a {‘age‘: 18, ‘name‘: ‘gm‘} >>> a[‘name‘]=‘root‘ >>> a {‘age‘: 18, ‘name‘: ‘root‘}
# 如何獲取字典某元素的值 >>> a {‘age‘: 18, ‘job‘: ‘運維‘, ‘name‘: ‘gm‘}
>>> a[‘gender‘] Traceback (most recent call last): File "<pyshell#51>", line 1, in <module> a[‘gender‘] KeyError: ‘gender‘
>>> a.get(‘gender‘) >>> a.get(‘gender‘,-1) -1
>>> a.get(‘name‘,-1) ‘gm‘
# 刪除字典某元素 >>> a {‘age‘: 18, ‘job‘: ‘運維‘, ‘name‘: ‘gm‘} >>> a.pop(‘job‘) ‘運維‘ >>> a {‘age‘: 18, ‘name‘: ‘gm‘} # 獲取字典刪除的元素的值
>>> a {‘age‘: 18, ‘job‘: ‘運維‘, ‘name‘: ‘gm‘} >>> c = a.pop(‘job‘) >>> c ‘運維‘ >>> a {‘age‘: 18, ‘name‘: ‘gm‘}
# Python3中字典的keys()、values()、items()方法的區別 >>> a.keys() # 以列表返回字典所有的鍵 dict_keys([‘age‘, ‘job‘, ‘name‘]) >>> a.values() # 以列表返回字典中的所有值 dict_values([18, ‘運維‘, ‘gm‘]) >>> a.items() # 以列表返回字典可遍歷的(鍵, 值) 元組數組 dict_items([(‘age‘, 18), (‘job‘, ‘運維‘), (‘name‘, ‘gm‘)])
5、字典練習
有如下值集合 [11,22,33,44,55,66,77,88,99,90...]， 將所有大於 66 的值保存至字典的第一個key中， 將小於 66 的值保存至第二個key的值中。 即： {‘k1‘: 大於66 , ‘k2‘: 小於66}
b = {} a = [11, 22, 33, 44, 55, 66, 77, 88, 99, 90, ] for i in a: if i > 66: if ‘k1‘ in b.keys(): b[‘k1‘].append(i) else: b[‘k1‘]= [i, ] else: if ‘k2‘ in b.keys(): b[‘k2‘].append(i) else: b[‘k2‘]= [i, ] print(b[‘k1‘]) print(b[‘k2‘])
Python 字典