腾讯课堂——基础数据类型(dict字典)

初识字典

标准类型

数字

字符串

列表

字典

元组

　　

      字典是Python语言中唯一的映射类型。

　　定义：｛key1:value1,key2:value2｝

　　　　    1、键与值用冒号“：”分开；
　　　　    2、项与项用逗号“，”分开；
　　特性：

　　　　　 1.key-value结构

　　　　    2.key必须可hash、且必须为不可变数据类型、必须唯一

　　　　    3.可存放任意多个值、可修改、可以不唯一

　　　　    4.无序

字典的创建

　　person = {"name": "alex", 'age': 20}
　　或
　　person = dict(name='seven', age=20)
　　person = dict({"name": "egon", 'age': 20})
　　person = dict((['name','苑昊'],['文周',18]))
　　{}.fromkeys(seq,100) #不指定100默认为None

　　注意：

>>> dic={}.fromkeys(['k1','k2'],[])
>>> dic
{'k1': [], 'k2': []}
>>> dic['k1'].append(1)
>>> dic
{'k1': [1], 'k2': [1]} 

字典的常用操作

　　键、值、键值对

　　　　1、dic.keys() 返回一个包含字典所有KEY的列表；
　　　　2、dic.values() 返回一个包含字典所有value的列表；
　　　　3、dic.items() 返回一个包含所有（键，值）元祖的列表；
　　　　4、dic.iteritems()、dic.iterkeys()、dic.itervalues() 与它们对应的非迭代方法一样，不同的是它们返回一个迭代子，而不是一个列表；

　　新增

　　　　1、dic['new_key'] = 'new_value'　

　　　　2、dic.setdefault(key, None) ,如果字典中不存在Key键，由 dic[key] = default 为它赋值；

　　删除

　　　　1、dic.pop(key[,default]) 和get方法相似。如果字典中存在key，删除并返回key对应的vuale；如果key不存在，且没有给出default的值，则引发keyerror异常；

　　　　2、dic.clear() 删除字典中的所有项或元素；

　　修改

　　　　1、dic['key'] = 'new_value',如果key在字典中存在，'new_value'将会替代原来的value值。

　　　　2、dic.update(dic2) 将字典dic2的键值对添加到字典dic中。

　　查看

　　　　1、dic['key']，返回字典中key对应的值，若key不存在字典中，则报错；

　　　　2、adict.get(key, default = None) 返回字典中key对应的值，若key不存在字典中，则返回default的值（default默认为None）；　　　

　　循环

　　长度

字典的工厂函数

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)
    """
    def clear(self): # real signature unknown; restored from __doc__
        """ D.clear() -> None.  Remove all items from D. """
        pass
<span style="color: #0000ff;">def</span> copy(self): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> D.copy() -&gt; a shallow copy of D </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span><span style="color: #000000;">

@staticmethod </span><span style="color: #008000;">#</span><span style="color: #008000;"> known case</span>
<span style="color: #0000ff;">def</span> fromkeys(*args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Returns a new dict with keys from iterable and values equal to value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> get(self, k, d=None): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> D.get(k[,d]) -&gt; D[k] if k in D, else d.  d defaults to None. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> items(self): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> D.items() -&gt; a set-like object providing a view on D's items </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> keys(self): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> D.keys() -&gt; a set-like object providing a view on D's keys </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> pop(self, k, d=None): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;">
    D.pop(k[,d]) -&gt; v, remove specified key and return the corresponding value.
    If key is not found, d is returned if given, otherwise KeyError is raised
    </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> popitem(self): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;">
    D.popitem() -&gt; (k, v), remove and return some (key, value) pair as a
    2-tuple; but raise KeyError if D is empty.
    </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> setdefault(self, k, d=None): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> D.setdefault(k[,d]) -&gt; D.get(k,d), also set D[k]=d if k not in D </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> update(self, E=None, **F): <span style="color: #008000;">#</span><span style="color: #008000;"> known special case of dict.update</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;">
    D.update([E, ]**F) -&gt; None.  Update D from dict/iterable E and F.
    If E is present and has a .keys() method, then does:  for k in E: D[k] = E[k]
    If E is present and lacks a .keys() method, then does:  for k, v in E: D[k] = v
    In either case, this is followed by: for k in F:  D[k] = F[k]
    </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> values(self): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> D.values() -&gt; an object providing a view on D's values </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__contains__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> True if D has a key k, else False. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__delitem__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Delete self[key]. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__eq__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return self==value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__getattribute__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return getattr(self, name). </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__getitem__</span>(self, y): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> x.__getitem__(y) &lt;==&gt; x[y] </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__ge__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return self&gt;=value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__gt__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return self&gt;value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__init__</span>(self, seq=None, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> known special case of dict.__init__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;">
    dict() -&gt; new empty dictionary
    dict(mapping) -&gt; new dictionary initialized from a mapping object's
        (key, value) pairs
    dict(iterable) -&gt; new dictionary initialized as if via:
        d = {}
        for k, v in iterable:
            d[k] = v
    dict(**kwargs) -&gt; new dictionary initialized with the name=value pairs
        in the keyword argument list.  For example:  dict(one=1, two=2)
    # (copied from class doc)
    </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__iter__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Implement iter(self). </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__len__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return len(self). </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__le__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return self&lt;=value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__lt__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return self&lt;value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span><span style="color: #000000;">

@staticmethod </span><span style="color: #008000;">#</span><span style="color: #008000;"> known case of __new__</span>
<span style="color: #0000ff;">def</span> <span style="color: #800080;">__new__</span>(*args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Create and return a new object.  See help(type) for accurate signature. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__ne__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return self!=value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__repr__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Return repr(self). </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__setitem__</span>(self, *args, **kwargs): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> Set self[key] to value. </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #0000ff;">def</span> <span style="color: #800080;">__sizeof__</span>(self): <span style="color: #008000;">#</span><span style="color: #008000;"> real signature unknown; restored from __doc__</span>
    <span style="color: #800000;">"""</span><span style="color: #800000;"> D.__sizeof__() -&gt; size of D in memory, in bytes </span><span style="color: #800000;">"""</span>
    <span style="color: #0000ff;">pass</span>

<span style="color: #800080;">__hash__</span> = None</pre>