python3.0以上,print函数应为print(),不存在dict.iteritems()这个函数。
在python中写中文注释会报错,这时只要在头部加上# coding=gbk即可
#字典的添加、删除、修改操作
dict = {"a" : "apple", "b" : "banana", "g" : "grape", "o" : "orange"}dict["w"] = "watermelon"del(dict["a"])dict["g"] = "grapefruit"print dict.pop("b")print dictdict.clear()print dict#字典的遍历dict = {"a" : "apple", "b" : "banana", "g" : "grape", "o" : "orange"}for k in dict: print "dict[%s] =" % k,dict[k]#字典items()的使用dict = {"a" : "apple", "b" : "banana", "c" : "grape", "d" : "orange"}#每个元素是一个key和value组成的元组,以列表的方式输出print dict.items()#调用items()实现字典的遍历dict = {"a" : "apple", "b" : "banana", "g" : "grape", "o" : "orange"}for (k, v) in dict.items(): print "dict[%s] =" % k, v#调用iteritems()实现字典的遍历dict = {"a" : "apple", "b" : "banana", "c" : "grape", "d" : "orange"}print dict.iteritems()for k, v in dict.iteritems(): print "dict[%s] =" % k, vfor (k, v) in zip(dict.iterkeys(), dict.itervalues()): print "dict[%s] =" % k, v #使用列表、字典作为字典的值dict = {"a" : ("apple",), "bo" : {"b" : "banana", "o" : "orange"}, "g" : ["grape","grapefruit"]}print dict["a"]print dict["a"][0]print dict["bo"]print dict["bo"]["o"]print dict["g"]print dict["g"][1] dict = {"a" : "apple", "b" : "banana", "c" : "grape", "d" : "orange"}#输出key的列表print dict.keys()#输出value的列表print dict.values()#每个元素是一个key和value组成的元组,以列表的方式输出print dict.items()dict = {"a" : "apple", "b" : "banana", "c" : "grape", "d" : "orange"}it = dict.iteritems()print it#字典中元素的获取方法dict = {"a" : "apple", "b" : "banana", "c" : "grape", "d" : "orange"}print dictprint dict.get("c", "apple") print dict.get("e", "apple")#get()的等价语句D = {"key1" : "value1", "key2" : "value2"}if "key1" in D: print D["key1"]else: print "None"#字典的更新dict = {"a" : "apple", "b" : "banana"}print dictdict2 = {"c" : "grape", "d" : "orange"}dict.update(dict2)print dict#udpate()的等价语句D = {"key1" : "value1", "key2" : "value2"}E = {"key3" : "value3", "key4" : "value4"}for k in E: D[k] = E[k]print D#字典E中含有字典D中的keyD = {"key1" : "value1", "key2" : "value2"}E = {"key2" : "value3", "key4" : "value4"}for k in E: D[k] = E[k]print D#设置默认值dict = {}dict.setdefault("a")print dictdict["a"] = "apple"dict.setdefault("a","default")print dict#调用sorted()排序dict = {"a" : "apple", "b" : "grape", "c" : "orange", "d" : "banana"}print dict #按照key排序 print sorted(dict.items(), key=lambda d: d[0])#按照value排序 print sorted(dict.items(), key=lambda d: d[1])#字典的浅拷贝dict = {"a" : "apple", "b" : "grape"}dict2 = {"c" : "orange", "d" : "banana"}dict2 = dict.copy()print dict2#字典的深拷贝import copydict = {"a" : "apple", "b" : {"g" : "grape","o" : "orange"}}dict2 = copy.deepcopy(dict)dict3 = copy.copy(dict)dict2["b"]["g"] = "orange"print dictdict3["b"]["g"] = "orange"print dict补充:1 初始化>>> d = dict(name='visaya', age=20)>>> d = dict(zip(['name', 'age'], ['visaya', 20]))#dict.fromkeys(listkeys, default=0) 把listkeys中的元素作为key均赋值为value,默认为0>>> d = dict.fromkeys(['a', 'b'], 1)>>> d{'a': 1, 'b': 1}2 字典视图和几何dict.keys()类似信使可以进行交集和并集等集合操作(类似集合,因为不存在重复的项),但dict.values()不可以进行如上操作。>>> k = d.keys()>>> kdict_keys(['a', 'b'])>>> list(k)['a', 'b']>>> k | {'x': 3}{'a', 'x', 'b'}>>> k | {'x'}{'a', 'x', 'b'}>>> k | {'x', 'y'}{'a', 'y', 'b', 'x'}>>> k & {'x'}set()>>> v = d.values()>>> vdict_values([1, 2])>>> v | {'x'}Traceback (most recent call last): File "<stdin>", line 1, in <module>TypeError: unsupported operand type(s) for |: 'dict_values' and 'set'3 排序字典键两种方法:3.1 sort:>>> Ks = list(d.keys())>>> Ks.sort()>>> for k in Ks:... print(k, d[k])... a 1b 23.2 sorted:>>> for k in sorted(d.keys()):... print(k, d[k])... a 1b 23.3 注意>>> for k in list(d.keys()).sort():... print(k, d[k])... Traceback (most recent call last): File "<stdin>", line 1, in <module>TypeError: 'NoneType' object is not iterable出错原因:list.sort() list.append()函数都是对自身的操作,没有返回值,故需先将list(d.keys())的结果保存下来,在结果上进行sort()4 常用函数4.1 get()D.get(k[, d]) => D[k] if k in D else d. d defaults to none.4.2 pop()D.pop(value[, d]) => Remove specified key and return the corresponding value. If key is not found, d is returned if given, otherwise KeyError is raised.4.3 udpate() 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]>>> d = dict(name='visaya', age=21)>>> d1= {'age': 20, 'sex': 'male'}>>> d2 = zip(['a', 'b'], [1, 2])>>> d.update(d1)>>> d{'age': 20, 'name': 'visaya', 'sex': 'male'}#for k in d1: d[k] = d1[k]>>> d.update(d2)>>> d{'age': 20, 'name': 'visaya', 'sex': 'male'}#for (k, v) in d2: d[k] = v4.4 del()del D[key]4.5 clear()4.6 copy()Python中的dict初始化构造方法创建Python代码 d = dict() d = dict(name="nico", age=23) d = dict((['name', "nico"], ['age', 23])) 当然还有更方便,简单的Python代码 d = {} d = {"name":"nico", "age":23} 遍历通过对key的遍历,遍历整个dict Python代码 d = {"name":"nico", "age":23} for key in d: print "key=%s, value=%s" % (key, d[key]) for key in d.iterkeys(): print "key=%s, value=%s" % (key, d[key]) for key in d.keys(): print "key=%s, value=%s" % (key, d[key]) for key in iter(d): print "key=%s, value=%s" % (key, d[key]) for key,item in d.items(): print "key=%s, value=%s" % (key, item) 当然也可以直接遍历value Python代码 d = {"name":"nico", "age":23} for value in d.values(): print value for key,value in d.viewitems(): print "key=%s, value=%s" % (key, value) for value in d.viewvalues(): print "value=%s" % (value) 这里values和viewvalues的区别 后者返回的是该字典的一个view对象,类似数据库中的view,当dict改变时,该view对象也跟着改变 常用方法 Python代码 d = {"name":"nico", "age":23} d["name"] = "aaaa" d["address"] = "abcdefg...." print d #{'age': 23, 'name': 'aaaa', 'address': 'abcdefg....'} 获取dict值Python代码 print d["name"] #nico print d.get("name") #nico 如果key不在dict中,返回default,没有为NonePython代码 print d.get("namex", "aaa") #aaa print d.get("namex") #None 排序sorted()Python代码 d = {"name":"nico", "age":23} for key in sorted(d): print "key=%s, value=%s" % (key, d[key]) #key=age, value=23 #key=name, value=nico 删除delPython代码 d = {"name":"nico", "age":23} Python代码 del d["name"] #如果key不在dict中,抛出KeyError del d["names"] Python代码 Traceback (most recent call last): File "F:\workspace\project\pydev\src\ddd\ddddd.py", line 64, in <module> del d["names"] KeyError: 'names' 清空clear()Python代码 d = {"name":"nico", "age":23} d.clear() print d #{} copy()Python代码 d1 = d.copy() #{'age': 23, 'name': 'nico'} #使用返回view对象 d2 = d1.viewitems() #dict_items([('age', 23), ('name', 'nico')]) #修改字典d1,新增元素 d1["cc"] = "aaaaaa" print d2 #dict_items([('cc', 'aaaaaa'), ('age', 23), ('name', 'nico')]) pop(key[, default])如果key在dict中,返回,不在返回defaultPython代码 #如果key在dict中,返回,不在返回default print d.pop("name", "niccco") #nico print d.pop("namezzz", "niccco") #niccco #key不在dict中,且default值也没有,抛出KeyError print d.pop("namezzz") #此处抛出KeyError popitem()删除并返回dict中任意的一个(key,value)队,如果字典为空会抛出KeyErrorPython代码 d = {"name":"nico", "age":23} print d.popitem() #('age', 23) print d.popitem() #('name', 'nico') #此时字典d已为空 print d.popitem() #此处会抛出KeyError update([other])将字典other中的元素加到dict中,key重复时将用other中的值覆盖Python代码 d = {"name":"nico", "age":23} d2 = {"name":"jack", "abcd":123} d.update(d2) print d #{'abcd': 123, 'age': 23, 'name': 'jack'}