用python自带的xml.etree.ElementTree模块和xml.dom.minidom模块生成xml文件标签的属性时,属性顺序会按照字典顺序重排,要想按照自己设定顺序来,可以使用lxml模块。
lxml模块不是python自带的,需要自己安装。
1. 写xml文件
a) 用etree和objectify
from lxml import etree, objectify
E = objectify.ElementMaker(annotate=False)
anno_tree = E.annotation(
E.folder('VOC2014_instance'),
E.filename("test.jpg"),
E.source(
E.database('COCO'),
E.annotation('COCO'),
E.image('COCO'),
E.url("http://test.jpg")
),
E.size(
E.width(),
E.height(),
E.depth()
),
E.segmented(),
)
etree.ElementTree(anno_tree).write("text.xml", pretty_print=True)
输出的test.xml文件内容如下:
```
如果需要在anno_tree的基础上加其他标签的话用append即可:
E2 = objectify.ElementMaker(annotate=False)
anno_tree2 = E2.object(
E.name("person"),
E.bndbox(
E.xmin(),
E.ymin(),
E.xmax(),
E.ymax()
),
E.difficult()
)
anno_tree.append(anno_tree2)
上面的输出就变成了:
<annotation>
<folder>VOC2014_instance/person</folder>
<filename>test.jpg</filename>
<source>
<database>COCO</database>
<annotation>COCO</annotation>
<image>COCO</image>
<url>http://test.jpg</url>
</source>
<size>
<width>800</width>
<height>600</height>
<depth>3</depth>
</size>
<segmented>0</segmented>
<object>
<name>person</name>
<bndbox>
<xmin>100</xmin>
<ymin>200</ymin>
<xmax>300</xmax>
<ymax>400</ymax>
</bndbox>
<difficult>0</difficult>
</object>
</annotation>
b) 用etree和SubElement
from lxml import etree
annotation = etree.Element("annotation")
etree.SubElement(annotation, "folder").text = "VOC2014_instance"
etree.SubElement(annotation, "filename").text = "test.jpg"
source = etree.SubElement(annotation, "source")
etree.SubElement(source, "database").text = "COCO"
etree.SubElement(source, "annotation").text = "COCO"
etree.SubElement(source, "image").text = "COCO"
etree.SubElement(source, "url").text = "http://test.jpg"
size = etree.SubElement(annotation, "size")
etree.SubElement(size, "width").text ='800' # 必须用string
etree.SubElement(size, "height").text = '600'
etree.SubElement(size, "depth").text = '3'
etree.SubElement(annotation, "segmented").text = '0'
key_object = etree.SubElement(annotation, "object")
etree.SubElement(key_object, "name").text = “person”
bndbox = etree.SubElement(key_object, "bndbox")
etree.SubElement(bndbox, "xmin").text = str()
etree.SubElement(bndbox, "ymin").text = str()
etree.SubElement(bndbox, "xmax").text = str()
etree.SubElement(bndbox, "ymax").text = str()
etree.SubElement(key_object, "difficult").text = '0'
doc = etree.ElementTree(annotation)
doc.write(open("test.xml", "w"), pretty_print=True)
2. 读xml
这里可以用xpath直接提取所需的元素的值。比如想要获取上面test.xml文件的x, y坐标:
tree = etree.parse("test.xml")
# get bbox
for bbox in tree.xpath('//bndbox'): # 获取bndbox元素的内容
for corner in bbox.getchildren(): # 便利bndbox元素下的子元素
print corner.text # string类型
参考:
https://blog.csdn.net/qq_16209077/article/details/55049877
https://www.cnblogs.com/arkenstone/p/7338978.html