Python 字典(Dictionary)

#DictionaryType.py
#_*_ coding:UTF-8 _*_\
#!/usr/bin/python

'''
Python 字典(Dictionary)
1. 另一种可变容器模型，且可存储任意类型对象。
2. 每个键值(key=>value)对用冒号(:)分割，每个对之间用逗号(,)分割，整个字典包括在花括号({})中 :d = {key1 : value1, key2 : value2 }
3. 键必须是唯一的，但值则不必。
4. 值可以取任何数据类型，但键必须是不可变的，如字符串，数字或元组。
5. 访问不存在的键，编译错误
6. 键存在，则修改键值； 键不存在，则新增元素
7. 不允许同一个键出现两次。创建时如果同一个键被赋值两次，后一个值会被记住
8. 键必须不可变，所以可以用数字，字符串或元组充当，而用列表就不行
9. 
'''

print("*****************  Python 字典(Dictionary)  *************************")
dcA = {"One": "Good", 5:"Study", "Test":1314}
print("dcA => ", dcA)

print("\n" + "*****************  访问字典里的元素  *************************")
dcA = {"One": "Good", 5:"Study", "Test":1314}
print("dcA => ", dcA)
print("dcA[5]: ", dcA[5])
print("dcA[\"Test\"]: ", dcA["Test"])
#print("dcA[1]: ", dcA[1])  #Error: 没有对应的 键

print("\n" + "*****************  修改字典的元素  *************************")
dcA = {"Name": "Zhansan", "Age":20, "Sex":"Man", "Grade":"Perfect"}
print("dcA => ", dcA)

dcA["Name"] = "Lisi"
dcA["Age"] = 22
print("dcA => ", dcA)

print("\n" + "*****************  增加字典的元素  *************************")
dcA = {"Name1": "Zhansan", "Age1":20, "Sex1":"Man"}
print("dcA => ", dcA)

print("dcA[\"Name2\"] = \"Xiaofang\"")
print("键存在，则修改键值； 键不存在，则新增元素")
dcA["Name2"] = "Xiaofang"   #键存在，则修改键值； 键不存在，则新增元素
dcA["Age2"] = 25            #键存在，则修改键值； 键不存在，则新增元素
dcA["Sex2"] = "Woman"       #键存在，则修改键值； 键不存在，则新增元素
print("dcA => ", dcA)

print("\n" + "*****************  删除字典  *************************")
dcA = {"Name": "Zhansan", "Age":20, "Sex":"Man", "Grade":"Perfect"}
print("dcA => ", dcA)

print("del dcA[\"Grade\"]")
del dcA["Grade"]    #删除键和键值
print("dcA => ", dcA)

del dcA #删除字典
#print("dcA => ", dcA)
print("del dcA  #Error: 字典删除后，再次访问会报错")

print("\n" + "*****************  字典键的特性  *************************")
print("1）不允许同一个键出现两次。创建时如果同一个键被赋值两次，后一个值会被记住")
dcA = {"Name": "Zhansan", "Age":20, "Sex":"Man", "Grade":"Perfect", "Sex":"Woman"}
print("dcA => ", dcA)

print("2）键必须不可变，所以可以用数字，字符串或元组充当，而用列表就不行")
dcB = {("Name", "Name2"): ("Zhansan", "Lisi"), "Age":20}
print("dcB => ", dcB)

dcB = {("Name", "Age"): ("Zhansan", 15), "Age":20, "Name": "Xiaofang"}
print("dcB => ", dcB)

print("\n" + "*****************  字典内置函数&方法  ********************")
dcA = {"Name": "Zhansan", "Age":20, "Sex":"Man", "Grade":"Perfect"}
print("dcA => ", dcA)
print("len(dcA) => ", len(dcA))

dcB = {("Name", "Name2"):("Zhansan", "Lisi"), "Age":20}
print("dcB => ", dcB)
print("len(dcB) => ", len(dcB))

strB = str(dcB)
print("strB = str(dcB)")
print("strB => ", strB)

#字典类型: type()
print("\n" + "字典类型")
print("type(dcB) => ", type(dcB))

#copy字典: copy()
print("\n" + "copy字典")
dcAA = dcA.copy()
print("dcAA = dcA.copy()")
print("dcAA => ", dcAA)

#创建新的字典，fromkeys（dcA）,dcA的键为新字典的键，值为初始值: fromkeys()
print("\n" + "创建新的字典，fromkeys（dcA）,dcA的键为新字典的键，值为初始值")
dcA1 = {"Name1": "Zhansan1", "Age1":21, "Sex1":"Man1", "Grade1":"Perfect1"}
dcA2 = {"Name2": "Zhansan2", "Age2":22, "Sex2":"Man2", "Grade2":"Perfect2"}
print("dcA1 => ", dcA1)
print("dcA2 => ", dcA2)
print("dcA12 = dcA1.fromkeys(dcA2)")
dcA12 = dcA1.fromkeys(dcA2)
print("dcA12 => ", dcA12)
print("dcA21 = dcA1.fromkeys(dcA1)")
dcA21 = dcA2.fromkeys(dcA1)
print("dcA21 => ", dcA21)

#返回指定键的值： get()
print("\n" + "返回指定键的值")
print("dcA => ", dcA)
v = dcA.get("Name")
print("v = dcA.get(\"Name\")")
print("v => ", v)
v = dcA.get("NAME", 100)
print("v = dcA.get(\"NAME\", 100)")#键不存在时，返回第二个参数
print("v => ", v)

#和get()类似, 如果键不存在于字典中，将会添加键并将值设为default: setdefault()
print("\n" + "和get()类似, 如果键不存在于字典中，将会添加键并将值设为default")
print("dcA => ", dcA)
v = dcA.setdefault("Name", "Lisi")
print("v = dcA.setdefault(\"Name\", \"Lisi\")")
print("dcA => ", dcA)
print("v => ", v)
v = dcA.setdefault("NAME", "Lisi")
print("v = dcA.setdefault(\"NAME\", \"Lisi\")")#键不存在时，返回第二个参数
print("dcA => ", dcA)
print("v => ", v)

#把字典dcA的键/值对更新到dcB里: dcB.update(dcA)
print("\n" + "把字典dcA的键/值对更新到dcB里: dcB.update(dcA)")
dcA = {"Name1": "Zhansan", "Age1":21}
dcB = {"Name2": "Lisi", "Age2":22}
print("dcA => ", dcA)
print("dcB => ", dcB)
dcB.update(dcA)
print("dcB.update(dcA)")
print("dcA => ", dcA)
print("dcB => ", dcB)

#打印所有的键或键值：keys()， values()
print("\n" + "打印所有的键或键值")
print("dcA => ", dcA)
print("dcA.keys() => ", dcA.keys())
print("dcA.values() => ", dcA.values())

#键是否存在字典里：in
print("\n" + "键是否存在字典里：in")
print("dcA => ", dcA)
print("\"Name\" in dcA => ", "Name" in dcA)
print("\"NAME\" in dcA => ", "NAME" in dcA)

#以列表返回可遍历的（键,值）元组数组: items()
print("\n" + "以列表返回可遍历的（键,值）元组数组: items()")
print("dcA => ", dcA)
tupleA = dcA.items()
print("tupleA = dcA.items()")
print("tupleA => ", tupleA)

#删除指定键对应的键值，返回被删除的键值，如果键不存在，则返回default： pop(key，default)
print("\n" + "删除指定键对应的键值，返回被删除的键值，如果键不存在，则返回default： pop(key，default)")
dcA = {"Name": "Lisi", "Age":20, "Sex": "M"}
print("dcA => ", dcA)

v = dcA.pop("Age1", 33)
print("v = dcA.pop(\"Age1\", 33)")
print("v => ", v)
print("dcA => ", dcA)

v = dcA.pop("Age", 33)
print("v = dcA.pop(\"Age\", 33)")
print("v => ", v)
print("dcA => ", dcA)

#随机返回，并删除字典中的一对键/值: popitem()
print("\n" + "随机返回，并删除字典中的一对键/值（一般删除末尾）: popitem()")
dcA = {"Name": "Lisi", "Age":20, "Sex": "M"}
print("dcA => ", dcA)

print("V = dcA.popitem()")
v = dcA.popitem()
print("v => ", v)
print("dcA => ", dcA)

#清空字典: clear()
print("\n" + "清空字典")
print("dcA => ", dcA)
dcA.clear()
print("dcA.clear()")
print("dcA => ", dcA)

print("\n" + "*****************  字典 无限极嵌套  ********************")
dcP = {"北京": {
                "海定区":["国贸", "CBD"],
                "朝阳区": ["北大", "清华", "圆明园"]
                },
       "深圳":{
                "南山区": ["腾讯", "TCL""安健"],
                "龙华": ["富士康", "华为"]
                },
       "赫章":{
           "城关镇":{
               "小河沟":["二中", "狮子湾", "职高", "英才中学"]},
           "野马川镇":
                {
                "平山乡":{
                   "对江村":{
                       "石板沟":{"冯家":["Fxz","Fxy"],"刘家":{"Lzg"},"朱家":{"Zzl"}},
                       "刘困塘":{"陈家", "朱家"}
                            },
                   "江南村":["七星关大桥", "夏曦纪念碑"]
                        },
               "野马川":{}
                }
             }
       }
print("dcP => ", dcP)

print("\n" + "访问嵌套字典")
print("for i in dcP[\"赫章\"][\"野马川镇\"][\"平山乡\"]:\
    print(i)")
for i in dcP["赫章"]["野马川镇"]["平山乡"]:
    print(i)