python 字典

1.创建字典

http://skyfen.iteye.com/blog/567571  Python字典的应用详解

方法①:

>>> dict1 = {}

>>> dict2 = {'name': 'earth', 'port': 80}

>>> dict1, dict2

({}, {'port': 80, 'name': 'earth'})



方法②:从Python 2.2 版本起

>>> fdict = dict((['x', 1], ['y', 2]))

>>> fdict

{'y': 2, 'x': 1}

2. 字典排序

http://www.kunli.info/2009/05/07/sorting-dictionaries-by-value-in-python/   Python中最快的字典排序方法

after sort the return is a list of tuple

def sort2(d,r=True):#从大到小 sort by value

    return sorted(d.iteritems(), key=lambda x: x[1] , reverse=r)

 

def sort2(d,r=False):#从小到大 sort by key

    return sorted(d.iteritems(), key=lambda x: x[0] , reverse=r)

 

 http://1.guotie.sinaapp.com/?p=19  对python的字典(dict)按键/值(key, value)排序

 

sortDic=sort2(dic,True)

3. 字典遍历

http://5iqiong.blog.51cto.com/2999926/806230  遍历python字典几种方法

http://docs.quantifiedcode.com/python-anti-patterns/readability/not_using_items_to_iterate_over_a_dictionary.html

脚本:

#!/usr/bin/python
dict={"a":"apple","b":"banana","o":"orange"}

print "##########dict######################"
for i in dict:
        print "dict[%s]=" % i,dict[i]

print "###########items#####################"
for k,v in  dict.items():
        print "dict[%s]=" % k,v

print "###########iteritems#################"
for k,v in dict.iteritems():
        print "dict[%s]=" % k,v

print "###########iterkeys,itervalues#######"
for k,v in zip(dict.iterkeys(),dict.itervalues()):
        print "dict[%s]=" % k,v

执行结果:

##########dict######################
dict[a]= apple
dict[b]= banana
dict[o]= orange
###########items#####################
dict[a]= apple
dict[b]= banana
dict[o]= orange
###########iteritems#################
dict[a]= apple
dict[b]= banana
dict[o]= orange
###########iterkeys,itervalues#######
dict[a]= apple
dict[b]= banana
dict[o]= orange

4. 查找元素has_key

dic={}

for i in words:

    if dic.has_key(i) is False:

        dic[i]=1

    else:

        dic[i]+=1

 

 5. 统计

while True >0:

        if dic.has_key(ky) is False:

            dic[ky]=1

        else:

            dic[ky]+=1