Python beginner-A few small examples of lists and dictionaries

1. Decoding and encoding

Unicode

Utf-8

Gbk

Conversion syntax format between character encodings: variable. Decode (' GBK '). Encode (' Utf-8 ') #decode解码, encode encoding

Expandtabs () #将tab处转换空格, default one tab=8 space

Example:>>> name = ' sy l '

>>> name.expandtabs (1) #如果括号内设定参数, parameters are converted into a few spaces

' Sy l '

>>> name.expandtabs (0)

' Syl '

Format () #字符串格式化

Example 1:>>> name = "I m {0},age {1}"

>>> Name.format (' Syl ', 73)

' I m syl,age 73 '

Example 2:>>> name = "I m {ss},age {DD}"

>>> Name.format (ss = ' syl1 ', dd=29)

' I m syl1,age 29 '

Example 3:>>> li = [2232,3333]

>>> name = "I m {0},age {1}"

>>> Name.format (*li) #如果格式化的时候传的参数是列表或元祖, add a * before the parameter

' I m 2232,age 3333 '

Example 4:

>>> name = "I m {ss},age {DD}"

>>> dic = {' ss ': 123, ' DD ': 456}

>>> Name.format (**dic) #如果格式化字符串的时候传的参数是字典, add two in front of the parameter *

' I m 123,age 456 '

Example 5:find () differs from index ()

>>> name = ' Syl1 '

>>> name.find (' s ')

0

>>> name.find (' B ')

-1

>>> Name.index (' s ')

0

>>> Name.index (' B ')

Traceback (most recent):

File "<stdin>", line 1, in <module>

Valueerror:substring not found

Example 6:join ()

>>> li = [' s1 ', ' S2 ']

>>> ' _ '. Join (LI) #列表连接

' S1_s2 '

2. List

Example 1:pop () #删除列表中的最后一个元素 and returns the contents of the deleted element

[' Oracle ', one, one, a, ' syl ', ' Wu ']

>>> Li.pop ()

' Wu '

>>> Li

[' Oracle ', one, A, a, ' syl ']

>>> name = Li.pop ()

>>> Name

' Syl '

>>> Li

[' Oracle ', 11, 22, 44]

3. Dictionaries

Example 1:

>>> dic = {' K1 ': 1234} #定义一个字典

>>> dic[' K1 '] #通过KEY获取字典的值

1234

>>> dic[' K2 '] #测试获取字典中没有的key是否会报错, resulting in an error, reflecting the advantages of the Get () method

Traceback (most recent):

File "<stdin>", line 1, in <module>

Keyerror: ' K2 '

>>> dic.get (' K1 ')

1234

>>> dic.get (' K2 ') #利用该方法获取没有的key值不会报错

>>> print dic.get (' K2 ')

None

>>> print dic.get (' K2 ', ' OK ') #如果获取的key没有, you can return the specified content by setting a second parameter

Ok

Example 2:

>>> ([A.fromkeys], ' t ')

{1: ' t ', 2: ' t ', 3: ' t '}

Update () #将两个字典的内容进行整合, if the consolidated dictionary key exists in the consolidated key during the integration process, replace the original value to ensure that there are no duplicate keys in the dictionary

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Python beginner-A few small examples of lists and dictionaries