我有一个看起来像这样的巨大xml文件
<environment>
<category name='category1'>
<peoples>
<people>
<name>Mary</name>
<city>NY</city>
<age>10</age>
</people>
<people>
<name>Jane</name>
<city>NY</city>
<age>19</age>
</people>
<people>
<name>John</name>
<city>NY</city>
<age>20</age>
</people>
<people>
<name>Carl</name>
<city>DC</city>
<age>11</age>
</people>
...
</people>
</category>
<category name='category2'>
...
</category
</environment>
我想将xml文件和输出解析为字典,其中的键是类别的名称(示例中的category1,category2)以及每个类别可能不同的值字典。现在,我只对类别1感兴趣,我想组成一个字典,其中的键是名称,值是年龄,它只包含居住在城市= NY的人
所以最终输出将是这样的:
{'cateogory1':{'Mary':10,'Jane':19,'John':20},'cateogory2':{}}
我先用iterparse尝试,但是遇到了内存错误:
result = {}
for _, element in etree.iterparse( 'file.xml', tag = 'category' ):
result[element.get('name')] = {}
if element.get('name') == 'category':
persons = {}
for person in element.findall('peoples/people'):
name, city, age = person.getchildren()
if city.text == 'NY':
persons[ name.text ] = age.text
result[element.get('name')] = persons
element.clear()
return results
因此,我的第二次尝试是使用SAX,但我对此并不熟悉。我从这里获取脚本开始,但是找不到将姓名与一个人的城市和年龄相关联的方法:
class CategoryParser(object):
def __init__( self, d ):
self.d = d
def start( self, start, attrib ):
if tag == 'category':
self.group = self.d[attrib['name']] = {}
elif tag == 'people':
#don't know how to access name, city and age for this person
def close( self ):
pass
result = {}
parser = lxml.etree.XMLParser( target=CategoryParser(result) )
lxml.etree.parse( 'file.xml', parser )
达到所需结果的最佳方法是什么?我愿意使用其他方法。
答案 0 :(得分:0)
您的lxml
方法看起来非常接近,但是我不确定为什么要使用MemoryError
。不过,您可以使用内置的xml.etree.ElementTree
轻松地做到这一点。
使用此xml(根据您的示例进行了一些修改):
xml = '''<environment>
<category name='category1'>
<peoples>
<people>
<name>Mary</name>
<city>NY</city>
<age>10</age>
</people>
<people>
<name>Jane</name>
<city>NY</city>
<age>19</age>
</people>
<people>
<name>John</name>
<city>NY</city>
<age>20</age>
</people>
<people>
<name>Carl</name>
<city>DC</city>
<age>11</age>
</people>
</peoples>
</category>
<category name='category2'>
<peoples>
<people>
<name>Mike</name>
<city>NY</city>
<age>200</age>
</people>
<people>
<name>Jimmy</name>
<city>HW</city>
<age>94</age>
</people>
</peoples>
</category>
</environment>'''
我这样做:
import xml.etree.ElementTree as ET
root = ET.fromstring(xml)
x = dict()
# Iterate all "category" nodes
for c in root.findall('./category'):
# Store "name" attribute
name = c.attrib['name']
# Insert empty dictionary for current category
x[name] = {}
# Iterate all people nodes contained in this category that have
# a child "city" node matching "NY"
for p in c.findall('./peoples/people[city="NY"]'):
# Get text of "name" child node
# (accessed by iterating parent node)
# i.e. "list(p)" -> [<Element 'name' at 0x04BB2750>, <Element 'city' at 0x04BB2900>, <Element 'age' at 0x04BB2A50>])
person_name = next(e for e in p if e.tag == 'name').text
# Same for "age" node, and convert to int
person_age = int(next(e for e in p if e.tag == 'age').text)
# Add entry to current category dictionary
x[name][person_name] = person_age
哪个给我以下字典:
{'category1': {'Mary': 10, 'Jane': 19, 'John': 20}, 'category2': {'Mike': 200}}
另外,关于示例xml的一些注释(可能只是复制/粘贴工件,但以防万一):
/peoples
节点缺少“ s” /category
节点缺少结束符“>” 答案 1 :(得分:0)
由于您使用lxml
并表示开放使用其他方法,请考虑使用XSLT,这是一种专用语言,旨在将XML文档转换为包括文本文件在内的各种格式。
具体来说,沿着树走,并根据节点值构建所需的花括号和引号。并且由于您所需的字典可以是有效的JSON,因此将您的XSLT结果导出为.json!
XSLT (另存为.xsl文件,特殊的.xml文件)
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output indent="yes" method="text"/>
<xsl:strip-space elements="*"/>
<xsl:variable name="pst">'</xsl:variable>
<xsl:template match="/environment">
<xsl:text>{
</xsl:text>
<xsl:apply-templates select="category"/>
<xsl:text>
}</xsl:text>
</xsl:template>
<xsl:template match="category">
<xsl:value-of select="concat(' ', $pst, @name, $pst, ': {')"/>
<xsl:apply-templates select="peoples/people[city='NY']"/>
<xsl:text>}</xsl:text>
<xsl:if test="position() != last()">
<xsl:text>,
</xsl:text>
</xsl:if>
</xsl:template>
<xsl:template match="people">
<xsl:value-of select="concat($pst, name, $pst, ': ', age)"/>
<xsl:if test="position() != last()">
<xsl:text>, </xsl:text>
</xsl:if>
</xsl:template>
</xsl:stylesheet>
Python (没有for
循环,if
逻辑或def
构建)
import ast
import lxml.etree as et
# LOAD XML AND XSL
xml = et.parse('Input.xml')
xsl = et.parse('Script.xsl')
# TRANSFORM INPUT
transformer = et.XSLT(xsl)
output_str = transformer(xml)
# BUILD DICT LITERALLY
new_dict = ast.literal_eval(str(output_str))
print(new_dict)
# {'category1': {'Mary': 10, 'Jane': 19, 'John': 20} }
# OUTPUT JSON
with open('Output.json', 'wb') as f:
f.write(output_str)
# {
# "category1": {"Mary": 10, "Jane": 19, "John": 20}
# }
Online Demo (具有用于演示的扩展节点)