python中怎么取出字典的键

举例如下：

1、新增python文件，testdictkeypy；

2、编写python代码，定义字典，并获取字典的key；

my_dict = dict(name="lili", age=32, money=1200, hourse=None)

key_list = my_dictkeys()

print(list(key_list))

3、选择‘在终端中运行Python文件’；

4、查看运行结果，可以输出字典的所有键；['name', 'age', 'money', 'hourse']

1

获取文件后缀名：

复制代码代码如下:

#!/usr/bin/python

import

os

dict

=

{}

for

d,

fd,

fl

in

oswalk('/home/ahda/Program/'):

for

f

in

fl:

sufix

=

ospathsplitext(f)[1][1:]

if

dicthas_key(sufix):

dict[sufix]

+=

1

else:

dict[sufix]

=

1

for

item

in

dictitems():

print

"%s

:

%s"

%

item

这里的关键是ospathsplitext()

如abc/efgh

，这里获取到的是h

2

python查找遍历指定文件路径下指定后缀名的文件实例：

复制代码代码如下:

import

os

import

sys

import

ospath

for

dirpath,

dirnames,

filenames

in

oswalk(startdir):

for

filename

in

filenames:

if

ospathsplitext(filename)[1]

==

'txt':

filepath

=

ospathjoin(dirpath,

filename)

#print("file:"

+

filepath)

input_file

=

open(filepath)

text

=

input_fileread()

input_fileclose()

output_file

=

open(

filepath,

'w')

output_filewrite(text)

output_fileclose()

3

批量重命名目录中的文件后缀实例：

复制代码代码如下:

import

os

def

swap_extensions(dir,

before,

after):

if

before[:1]

!=

'':

#如果参数中的后缀名没有''则加上

before

=

''

+

before

thelen

=

-len(before)

if

after[:1]

!=

'':

after

=

''

+

after

for

path,

subdir,

files

in

oswalk(dir):

for

oldfile

in

files:

if

oldfile[thelen:]

==

before:

oldfile

=

ospathjoin(path,

oldfile)

newfile

=

oldfile[:thelen]

+

after

osrename(oldfile,

newfile)

print

oldfile

+'

changed

to

'

+

newfile

if

__name__

==

'__main__':

import

sys

if

len(sysargv)

!=

4:

print

'Usage:swap_extensionpy

rootdir

before

after'

sysexit(1)

swap_extensions(sysargv[1],

sysargv[2],

sysargv[3])

例子:将e:/py/test目录下php结尾的文件重命名为py

E:py>python_cook

e:/py/test

php

py

e:/py/testtestphp

changed

to

e:/py/testtestpy

e:/py/test1php

changed

to

e:/py/test1py

e:/py/test2php

changed

to

e:/py/test2py

city_menu={"BJ":{"dongcheng":{"size":4184,"people":919,"code":100010},

"xicheng":{"size":5070,"people":1243,"code":100032},

"chaoyang":{"size":4708,"people":3083,"code":100020}},

"GZ":{"yuexiu":{"size":3380,"people":115,"code":510030},

"liwan":{"size":5910,"Mpeople":89,"code":510145},

"tianhe":{"size":9633,"people":143,"code":510630},

"haizhu":{"size":9040,"people":155,"code":510220}},

"SZ":{"futian":{"size":7866,"people":13571,"code":518000},

"nanshan":{"size":18549,"people":11359,"code":518000},

"luohu":{"size":7876,"people":9537,"code":518001}}}

d={}

for k0,v0 in city_menuitems():

for k1,v1 in v0items():

d[v1['code']]=k0+"-"+k1

def city():

qu=input('请输入邮政编码：')

if int(qu) in d:

return print('邮政编码为：%s 的城市是%s。' %(qu,d[int(qu)]))

else:

print('输入错误！')

items()返回的是列表对象，而iteritems()返回的是iterator对象。例如：

print dicitems() #[('a', 'hello'), ('c', 'you'), ('b', 'how')]

print diciteritems() #<dictionary-itemiterator object at 0x020E9A50>

深究：iteritor是迭代器的意思，一次反悔一个数据项，知道没有为止

for i in diciteritems():

print i

结果：('a', 'hello')

('c', 'you')

('b', 'how')

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