Python Dict用法
python]dictionary方法说明2007-05-19 23:24
申明 m={};
dictionary方法说明
2007-03-13 18:10
OperationResultNoteslen(a)the number of items ina 得到字典中元素的个数
athe item ofawith keyk 取得键K所对应的值
(1), (10)a =vsetatov 设定键k所对应的值成为v
delaremoveafroma 从字典中删除键为k的元素
(1)a.clear()remove all items froma 清空整个字典
a.copy()a (shallow) copy ofa 得到字典副本
kinaTrueifahas a keyk, elseFalse 字典中存在键k则为返回True，没有则返回False
(2)knot inaEquivalent tonotkina字典中不存在键k则为返回true,反之返回False(2)a.has_key(k)Equivalent tokina, use that form in new code 等价于k in a a.items()a copy ofa's list of (key,value) pairs 得到一个键，值的list(3)a.keys()a copy ofa's list of keys 得到键的list(3)a.update()updates (and overwrites) key/value pairs fromb从b字典中更新a字典，如果键相同则更新，a中不存在则追加(9)a.fromkeys(seq[,value])Creates a new dictionary with keys fromseqand values set tovalue
(7)a.values()a copy ofa's list of values(3)a.get(k[,x])aifkina, elsex(4)a.setdefault(k[,x])aifkina, elsex(also setting it)(5)a.pop(k[,x])aifkina, elsex(and remove k)(8)a.popitem()remove and return an arbitrary (key,value) pair(6)a.iteritems()return an iterator over (key,value) pairs(2), (3)a.iterkeys()return an iterator over the mapping's keys(2), (3)a.itervalues()return an iterator over the mapping's values(2), (3)
#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 dict
dict.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
#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, v
for (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"]
print dict["bo"]
print dict["bo"]["o"]
print dict["g"]
print dict["g"]
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 dict
print 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 dict
dict2 = {"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 = E
print D
#字典E中含有字典D中的key
D = {"key1" : "value1", "key2" : "value2"}
E = {"key2" : "value3", "key4" : "value4"}
for k in E:
D = E
print D
#设置默认值
dict = {}
dict.setdefault("a")
print dict
dict["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)
#按照value排序
print sorted(dict.items(), key=lambda d: d)
#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 copy
dict = {"a" : "apple", "b" : {"g" : "grape","o" : "orange"}}
dict2 = copy.deepcopy(dict)
dict3 = copy.copy(dict)
dict2["b"]["g"] = "orange"
print dict
dict3["b"]["g"] = "orange"
print dict
转载163某博客
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