python常用模块整理
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一.序列化
Python中用于序列化的两个模块
- json 用于【字符串】和 【python基本数据类型】 间进行转换
- pickle 用于【python特有的类型】 和 【python基本数据类型】间进行转换
Json模块提供了四个功能：dumps、dump、loads、load
Json.loads()用于将字典，列表形式的字符串转换成相应的字典,列表
Json.dump()将基本数据类型，列表，字典，转换成字符串
pickle模块提供了四个功能：dumps、dump、loads、load
二.安装第三方模块
第1种安装方法：
安装软件管理工具pip3 (python3中自带了pip3)
将pip3添加到环境变量
pip3 install 被安装的东西
第2种安装方法：
下载代码，安装
三.requests模块
Python标准库中提供了：urllib等模块以供Http请求，但是，它的 API 太渣了。它是为另一个时代、另一个互联网所创建的。它需要巨量的工作，甚至包括各种方法覆盖，来完成最简单的任务。
import urllib.request f = urllib.request.urlopen(‘http://www.webxml.com.cn//webservices/qqOnlineWebService.asmx/qqCheckOnline?qqCode=424662508‘) result = f.read().decode(‘utf-8‘)
import urllib.request req = urllib.request.Request(‘http://www.example.com/‘) req.add_header(‘Referer‘, ‘http://www.python.org/‘) r = urllib.request.urlopen(req) result = f.read().decode(‘utf-8‘)
注：更多见Python官方文档：https://docs.python.org/3.5/library/urllib.request.html#module-urllib.request
Requests 是使用 Apache2 Licensed 许可证的 基于Python开发的HTTP 库，其在Python内置模块的基础上进行了高度的封装，从而使得Pythoner进行网络请求时，变得美好了许多，使用Requests可以轻而易举的完成浏览器可有的任何操作。
1、安装模块
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pip3 install requests |
2、使用模块
# 1、无参数实例 import requests ret = requests.get(‘https://github.com/timeline.json‘) print(ret.url) print(ret.text) # 2、有参数实例 import requests payload = {‘key1‘: ‘value1‘, ‘key2‘: ‘value2‘} ret = requests.get("http://httpbin.org/get", params=payload) print(ret.url) print(ret.text) GET请求
# 1、基本POST实例 import requests payload = {‘key1‘: ‘value1‘, ‘key2‘: ‘value2‘} ret = requests.post("http://httpbin.org/post", data=payload) print(ret.text) # 2、发送请求头和数据实例 import requests import json url = ‘https://api.github.com/some/endpoint‘ payload = {‘some‘: ‘data‘} headers = {‘content-type‘: ‘application/json‘} ret = requests.post(url, data=json.dumps(payload), headers=headers) print(ret.text) print(ret.cookies) POST请求
requests.get(url, params=None, **kwargs) requests.post(url, data=None, json=None, **kwargs) requests.put(url, data=None, **kwargs) requests.head(url, **kwargs) requests.delete(url, **kwargs) requests.patch(url, data=None, **kwargs) requests.options(url, **kwargs) # 以上方法均是在此方法的基础上构建 requests.request(method, url, **kwargs) 其他请求
更多requests模块相关的文档见：http://cn.python-requests.org/zh_CN/latest/
四.XML模块
XML是实现不同语言或程序之间进行数据交换的协议，XML文件格式如下：
<data>
<country name="Liechtenstein">
<rank updated="yes">2</rank>
<year>2023</year>
<gdppc>141100</gdppc>
<neighbor direction="E" name="Austria" />
<neighbor direction="W" name="Switzerland" />
</country>
<country name="Singapore">
<rank updated="yes">5</rank>
<year>2026</year>
<gdppc>59900</gdppc>
<neighbor direction="N" name="Malaysia" />
</country>
<country name="Panama">
<rank updated="yes">69</rank>
<year>2026</year>
<gdppc>13600</gdppc>
<neighbor direction="W" name="Costa Rica" />
<neighbor direction="E" name="Colombia" />
</country>
</data>
1、解析XML
from xml.etree import ElementTree as ET # 打开文件，读取XML内容 str_xml = open(‘xo.xml‘, ‘r‘).read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) 利用ElementTree.XML将字符串解析成xml对象
from xml.etree import ElementTree as ET # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() 利用ElementTree.parse将文件直接解析成xml对象
2、操作XML
XML格式类型是节点嵌套节点，对于每一个节点均有以下功能，以便对当前节点进行操作：
class Element: """An XML element. This class is the reference implementation of the Element interface. An element‘s length is its number of subelements. That means if you want to check if an element is truly empty, you should check BOTH its length AND its text attribute. The element tag, attribute names, and attribute values can be either bytes or strings. *tag* is the element name. *attrib* is an optional dictionary containing element attributes. *extra* are additional element attributes given as keyword arguments. Example form: <tag attrib>text<child/>...</tag>tail """ 当前节点的标签名 tag = None """The element‘s name.""" 当前节点的属性 attrib = None """Dictionary of the element‘s attributes.""" 当前节点的内容 text = None """ Text before first subelement. This is either a string or the value None. Note that if there is no text, this attribute may be either None or the empty string, depending on the parser. """ tail = None """ Text after this element‘s end tag, but before the next sibling element‘s start tag. This is either a string or the value None. Note that if there was no text, this attribute may be either None or an empty string, depending on the parser. """ def __init__(self, tag, attrib={}, **extra): if not isinstance(attrib, dict): raise TypeError("attrib must be dict, not %s" % ( attrib.__class__.__name__,)) attrib = attrib.copy() attrib.update(extra) self.tag = tag self.attrib = attrib self._children = [] def __repr__(self): return "<%s %r at %#x>" % (self.__class__.__name__, self.tag, id(self)) def makeelement(self, tag, attrib): 创建一个新节点 """Create a new element with the same type. *tag* is a string containing the element name. *attrib* is a dictionary containing the element attributes. Do not call this method, use the SubElement factory function instead. """ return self.__class__(tag, attrib) def copy(self): """Return copy of current element. This creates a shallow copy. Subelements will be shared with the original tree. """ elem = self.makeelement(self.tag, self.attrib) elem.text = self.text elem.tail = self.tail elem[:] = self return elem def __len__(self): return len(self._children) def __bool__(self): warnings.warn( "The behavior of this method will change in future versions. " "Use specific ‘len(elem)‘ or ‘elem is not None‘ test instead.", FutureWarning, stacklevel=2 ) return len(self._children) != 0 # emulate old behaviour, for now def __getitem__(self, index): return self._children[index] def __setitem__(self, index, element): # if isinstance(index, slice): # for elt in element: # assert iselement(elt) # else: # assert iselement(element) self._children[index] = element def __delitem__(self, index): del self._children[index] def append(self, subelement): 为当前节点追加一个子节点 """Add *subelement* to the end of this element. The new element will appear in document order after the last existing subelement (or directly after the text, if it‘s the first subelement), but before the end tag for this element. """ self._assert_is_element(subelement) self._children.append(subelement) def extend(self, elements): 为当前节点扩展 n 个子节点 """Append subelements from a sequence. *elements* is a sequence with zero or more elements. """ for element in elements: self._assert_is_element(element) self._children.extend(elements) def insert(self, index, subelement): 在当前节点的子节点中插入某个节点，即：为当前节点创建子节点，然后插入指定位置 """Insert *subelement* at position *index*.""" self._assert_is_element(subelement) self._children.insert(index, subelement) def _assert_is_element(self, e): # Need to refer to the actual Python implementation, not the # shadowing C implementation. if not isinstance(e, _Element_Py): raise TypeError(‘expected an Element, not %s‘ % type(e).__name__) def remove(self, subelement): 在当前节点在子节点中删除某个节点 """Remove matching subelement. Unlike the find methods, this method compares elements based on identity, NOT ON tag value or contents. To remove subelements by other means, the easiest way is to use a list comprehension to select what elements to keep, and then use slice assignment to update the parent element. ValueError is raised if a matching element could not be found. """ # assert iselement(element) self._children.remove(subelement) def getchildren(self): 获取所有的子节点（废弃） """(Deprecated) Return all subelements. Elements are returned in document order. """ warnings.warn( "This method will be removed in future versions. " "Use ‘list(elem)‘ or iteration over elem instead.", DeprecationWarning, stacklevel=2 ) return self._children def find(self, path, namespaces=None): 获取第一个寻找到的子节点 """Find first matching element by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return the first matching element, or None if no element was found. """ return ElementPath.find(self, path, namespaces) def findtext(self, path, default=None, namespaces=None): 获取第一个寻找到的子节点的内容 """Find text for first matching element by tag name or path. *path* is a string having either an element tag or an XPath, *default* is the value to return if the element was not found, *namespaces* is an optional mapping from namespace prefix to full name. Return text content of first matching element, or default value if none was found. Note that if an element is found having no text content, the empty string is returned. """ return ElementPath.findtext(self, path, default, namespaces) def findall(self, path, namespaces=None): 获取所有的子节点 """Find all matching subelements by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Returns list containing all matching elements in document order. """ return ElementPath.findall(self, path, namespaces) def iterfind(self, path, namespaces=None): 获取所有指定的节点，并创建一个迭代器（可以被for循环） """Find all matching subelements by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return an iterable yielding all matching elements in document order. """ return ElementPath.iterfind(self, path, namespaces) def clear(self): 清空节点 """Reset element. This function removes all subelements, clears all attributes, and sets the text and tail attributes to None. """ self.attrib.clear() self._children = [] self.text = self.tail = None def get(self, key, default=None): 获取当前节点的属性值 """Get element attribute. Equivalent to attrib.get, but some implementations may handle this a bit more efficiently. *key* is what attribute to look for, and *default* is what to return if the attribute was not found. Returns a string containing the attribute value, or the default if attribute was not found. """ return self.attrib.get(key, default) def set(self, key, value): 为当前节点设置属性值 """Set element attribute. Equivalent to attrib[key] = value, but some implementations may handle this a bit more efficiently. *key* is what attribute to set, and *value* is the attribute value to set it to. """ self.attrib[key] = value def keys(self): 获取当前节点的所有属性的 key """Get list of attribute names. Names are returned in an arbitrary order, just like an ordinary Python dict. Equivalent to attrib.keys() """ return self.attrib.keys() def items(self): 获取当前节点的所有属性值，每个属性都是一个键值对 """Get element attributes as a sequence. The attributes are returned in arbitrary order. Equivalent to attrib.items(). Return a list of (name, value) tuples. """ return self.attrib.items() def iter(self, tag=None): 在当前节点的子孙中根据节点名称寻找所有指定的节点，并返回一个迭代器（可以被for循环）。 """Create tree iterator. The iterator loops over the element and all subelements in document order, returning all elements with a matching tag. If the tree structure is modified during iteration, new or removed elements may or may not be included. To get a stable set, use the list() function on the iterator, and loop over the resulting list. *tag* is what tags to look for (default is to return all elements) Return an iterator containing all the matching elements. """ if tag == "*": tag = None if tag is None or self.tag == tag: yield self for e in self._children: yield from e.iter(tag) # compatibility def getiterator(self, tag=None): # Change for a DeprecationWarning in 1.4 warnings.warn( "This method will be removed in future versions. " "Use ‘elem.iter()‘ or ‘list(elem.iter())‘ instead.", PendingDeprecationWarning, stacklevel=2 ) return list(self.iter(tag)) def itertext(self): 在当前节点的子孙中根据节点名称寻找所有指定的节点的内容，并返回一个迭代器（可以被for循环）。 """Create text iterator. The iterator loops over the element and all subelements in document order, returning all inner text. """ tag = self.tag if not isinstance(tag, str) and tag is not None: return if self.text: yield self.text for e in self: yield from e.itertext() if e.tail: yield e.tail 节点功能一览表
由于 每个节点 都具有以上的方法，并且在上一步骤中解析时均得到了root（xml文件的根节点），so 可以利用以上方法进行操作xml文件。
a. 遍历XML文档的所有内容
from xml.etree import ElementTree as ET ############ 解析方式一 ############ """ # 打开文件，读取XML内容 str_xml = open(‘xo.xml‘, ‘r‘).read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) """ ############ 解析方式二 ############ # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() ### 操作 # 顶层标签 print(root.tag) # 遍历XML文档的第二层 for child in root: # 第二层节点的标签名称和标签属性 print(child.tag, child.attrib) # 遍历XML文档的第三层 for i in child: # 第二层节点的标签名称和内容 print(i.tag,i.text)
b、遍历XML中指定的节点
from xml.etree import ElementTree as ET ############ 解析方式一 ############ """ # 打开文件，读取XML内容 str_xml = open(‘xo.xml‘, ‘r‘).read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) """ ############ 解析方式二 ############ # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() ### 操作 # 顶层标签 print(root.tag) # 遍历XML中所有的year节点 for node in root.iter(‘year‘): # 节点的标签名称和内容 print(node.tag, node.text)
c、修改节点内容
由于修改的节点时，均是在内存中进行，其不会影响文件中的内容。所以，如果想要修改，则需要重新将内存中的内容写到文件。
from xml.etree import ElementTree as ET ############ 解析方式一 ############ # 打开文件，读取XML内容 str_xml = open(‘xo.xml‘, ‘r‘).read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) ############ 操作 ############ # 顶层标签 print(root.tag) # 循环所有的year节点 for node in root.iter(‘year‘): # 将year节点中的内容自增一 new_year = int(node.text) + 1 node.text = str(new_year) # 设置属性 node.set(‘name‘, ‘alex‘) node.set(‘age‘, ‘18‘) # 删除属性 del node.attrib[‘name‘] ############ 保存文件 ############ tree = ET.ElementTree(root) tree.write("newnew.xml", encoding=‘utf-8‘) 解析字符串方式，修改，保存
from xml.etree import ElementTree as ET ############ 解析方式二 ############ # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() ############ 操作 ############ # 顶层标签 print(root.tag) # 循环所有的year节点 for node in root.iter(‘year‘): # 将year节点中的内容自增一 new_year = int(node.text) + 1 node.text = str(new_year) # 设置属性 node.set(‘name‘, ‘alex‘) node.set(‘age‘, ‘18‘) # 删除属性 del node.attrib[‘name‘] ############ 保存文件 ############ tree.write("newnew.xml", encoding=‘utf-8‘) 解析文件方式，修改，保存
d、删除节点
from xml.etree import ElementTree as ET ############ 解析字符串方式打开 ############ # 打开文件，读取XML内容 str_xml = open(‘xo.xml‘, ‘r‘).read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) ############ 操作 ############ # 顶层标签 print(root.tag) # 遍历data下的所有country节点 for country in root.findall(‘country‘): # 获取每一个country节点下rank节点的内容 rank = int(country.find(‘rank‘).text) if rank > 50: # 删除指定country节点 root.remove(country) ############ 保存文件 ############ tree = ET.ElementTree(root) tree.write("newnew.xml", encoding=‘utf-8‘) 解析字符串方式打开，删除，保存
from xml.etree import ElementTree as ET ############ 解析文件方式 ############ # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() ############ 操作 ############ # 顶层标签 print(root.tag) # 遍历data下的所有country节点 for country in root.findall(‘country‘): # 获取每一个country节点下rank节点的内容 rank = int(country.find(‘rank‘).text) if rank > 50: # 删除指定country节点 root.remove(country) ############ 保存文件 ############ tree.write("newnew.xml", encoding=‘utf-8‘) 解析文件方式打开，删除，保存
3、创建XML文档
from xml.etree import ElementTree as ET # 创建根节点 root = ET.Element("famliy") # 创建节点大儿子 son1 = ET.Element(‘son‘, {‘name‘: ‘儿1‘}) # 创建小儿子 son2 = ET.Element(‘son‘, {"name": ‘儿2‘}) # 在大儿子中创建两个孙子 grandson1 = ET.Element(‘grandson‘, {‘name‘: ‘儿11‘}) grandson2 = ET.Element(‘grandson‘, {‘name‘: ‘儿12‘}) son1.append(grandson1) son1.append(grandson2) # 把儿子添加到根节点中 root.append(son1) root.append(son1) tree = ET.ElementTree(root) tree.write(‘oooo.xml‘,encoding=‘utf-8‘, short_empty_elements=False) 创建方式（一）
from xml.etree import ElementTree as ET #
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