嵌套字典练习：
av_catalog = {
"欧美":{
"www.youporn.com": ["很多免费的,世界最大的","质量一般"],
"www.pornhub.com": ["很多免费的,也很大","质量比yourporn高点"],
"letmedothistoyou.com": ["多是自拍,高质量图片很多","资源不多,更新慢"],
"x-art.com":["质量很高,真的很高","全部收费,屌比请绕过"]
},
"日韩":{
"tokyo-hot":["质量怎样不清楚,个人已经不喜欢日韩范了","听说是收费的"]
},
"大陆":{
"1024":["全部免费,真好,好人一生平安","服务器在国外,慢"]
}
}
av_catalog["大陆"]["1024"][1] += ",可以用爬虫爬下来"
print(av_catalog["大陆"]["1024"])
#ouput
[‘全部免费,真好,好人一生平安‘, ‘服务器在国外,慢,可以用爬虫爬下来‘]
集合的练习：
s = set([3,5,9,10]) #创建一个数值集合
t = set("Hello") #创建一个唯一字符的集合
a = t | s # t 和 s的并集
b = t & s # t 和 s的交集
c = t – s # 求差集（项在t中，但不在s中）
d = t ^ s # 对称差集（项在t或s中，但不会同时出现在二者中）
基本操作：
t.add(‘x‘) # 添加一项
s.update([10,37,42]) # 在s中添加多项
使用remove()可以删除一项：
t.remove(‘H‘)
len(s)
set 的长度
x in s
测试 x 是否是 s 的成员
x not in s
测试 x 是否不是 s 的成员
s.issubset(t)
s <= t
测试是否 s 中的每一个元素都在 t 中
s.issuperset(t)
s >= t
测试是否 t 中的每一个元素都在 s 中
s.union(t)
s | t
返回一个新的 set 包含 s 和 t 中的每一个元素
s.intersection(t)
s & t
返回一个新的 set 包含 s 和 t 中的公共元素
s.difference(t)
s - t
返回一个新的 set 包含 s 中有但是 t 中没有的元素
s.symmetric_difference(t)
s ^ t
返回一个新的 set 包含 s 和 t 中不重复的元素
s.copy()
返回 set “s”的一个浅复制
打开文件操作：
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基本操作
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打开文件的模式有：
- r，只读模式（默认）。
- w，只写模式。【不可读；不存在则创建；存在则删除内容；】
- a，追加模式。【可读； 不存在则创建；存在则只追加内容；】
"+" 表示可以同时读写某个文件
- r+，可读写文件。【可读；可写；可追加】
- w+，写读
- a+，同a
"U"表示在读取时，可以将 \r \n \r\n自动转换成 \n （与 r 或 r+ 模式同使用）
- rU
- r+U
"b"表示处理二进制文件（如：FTP发送上传ISO镜像文件，linux可忽略，windows处理二进制文件时需标注）
- rb
- wb
- ab
其它语法
def close(self): # real signature unknown; restored from __doc__
"""
Close the file.
A closed file cannot be used for further I/O operations. close() may be
called more than once without error.
"""
pass
def fileno(self, *args, **kwargs): # real signature unknown
""" Return the underlying file descriptor (an integer). """
pass
def isatty(self, *args, **kwargs): # real signature unknown
""" True if the file is connected to a TTY device. """
pass
def read(self, size=-1): # known case of _io.FileIO.read
"""
注意，不一定能全读回来
Read at most size bytes, returned as bytes.
Only makes one system call, so less data may be returned than requested.
In non-blocking mode, returns None if no data is available.
Return an empty bytes object at EOF.
"""
return ""
def readable(self, *args, **kwargs): # real signature unknown
""" True if file was opened in a read mode. """
pass
def readall(self, *args, **kwargs): # real signature unknown
"""
Read all data from the file, returned as bytes.
In non-blocking mode, returns as much as is immediately available,
or None if no data is available. Return an empty bytes object at EOF.
"""
pass
def readinto(self): # real signature unknown; restored from __doc__
""" Same as RawIOBase.readinto(). """
pass #不要用,没人知道它是干嘛用的
def seek(self, *args, **kwargs): # real signature unknown
"""
Move to new file position and return the file position.
Argument offset is a byte count. Optional argument whence defaults to
SEEK_SET or 0 (offset from start of file, offset should be >= 0); other values
are SEEK_CUR or 1 (move relative to current position, positive or negative),
and SEEK_END or 2 (move relative to end of file, usually negative, although
many platforms allow seeking beyond the end of a file).
Note that not all file objects are seekable.
"""
pass
def seekable(self, *args, **kwargs): # real signature unknown
""" True if file supports random-access. """
pass
def tell(self, *args, **kwargs): # real signature unknown
"""
Current file position.
Can raise OSError for non seekable files.
"""
pass
def truncate(self, *args, **kwargs): # real signature unknown
"""
Truncate the file to at most size bytes and return the truncated size.
Size defaults to the current file position, as returned by tell().
The current file position is changed to the value of size.
"""
pass
def writable(self, *args, **kwargs): # real signature unknown
""" True if file was opened in a write mode. """
pass
def write(self, *args, **kwargs): # real signature unknown
"""
Write bytes b to file, return number written.
Only makes one system call, so not all of the data may be written.
The number of bytes actually written is returned. In non-blocking mode,
returns None if the write would block.
"""
pass
with语句
为了避免打开文件后忘记关闭，可以通过管理上下文，即：
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如此方式，当with代码块执行完毕时，内部会自动关闭并释放文件资源。
在Python 2.7 后，with又支持同时对多个文件的上下文进行管理，即：
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