在流式传输XML时删除元素之间的空行

Question

我正在使用iterparse来填充Python中的大型（~1GB）XML文件。一切看起来都不错，除了我无法在empty lines标签之后删除那些</ROW>。

我尝试添加elem.text.strip()+"\n\t\t和elem.tail.strip()+"\n\t，这是有效的。但我不确定这是否是处理它的最佳方法以及如何在tab标记之前移除</data>。

我的XML

xml_str = """
<DATA>

    <ROW>
        <assmtid>1</assmtid>
        <Year>1988</Year>
    </ROW>

    <ROW>
        <assmtid>2</assmtid>
        <Year>NULL</Year>
    </ROW>

    <ROW>
        <assmtid>2</assmtid>
        <Year>1990</Year>
    </ROW>

</DATA>
"""

代码

def getelements(pth, ele_xml):
    context = iter(etree.iterparse(StringIO(xml_str), events=('start', 'end')))
    event, root = next(context)

    for event, elem in context:
        if event == 'end' and elem.tag == "ROW":
            elem.tag = elem.tag.lower()
            elem.text = elem.text.strip()+"\n\t\t"
            elem.tail = elem.tail.strip()+"\n\t"

            for child in elem:
                child.tag = child.tag.lower()
                if child.text == "NULL":
                    child.text = ""  
                if child.text == None:
                    child.text = ""
                # print event, elem.tag
            yield elem
            root.clear()

with open(pth_new_to_xml, 'wb') as file:
    # start root
    file.write('<data>\n\r')
    for page in getelements(pth, ele_xml):
        file.write(etree.tostring(page, encoding='utf-8'))
    # close root
    file.write('</data>')

当前输出

<data>
    <row>
        <assmtid>1</assmtid>
        <year>1988</year>
    </row>
    <row>
        <assmtid>2</assmtid>
        <year />
    </row>
    <row>
        <assmtid>2</assmtid>
        <year>1990</year>
    </row>
    </data>