Home > Article > Backend Development > Example sharing of how Python uses lxml to read and write xml format files
This article mainly introduces python to use lxml to read and write files in xml format. It has certain reference value. Interested friends can refer to
before converting the data set format. Sometimes you need to convert json to xml file, and it is very convenient to use the lxml package.
1. Write xml file
a) Test.xml output using etree and 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(800), E.height(600), E.depth(3) ), E.segmented(0), ) etree.ElementTree(anno_tree).write("text.xml", pretty_print=True)The content of the file is as follows: "If you need to add other tags on the basis of anno_tree, just use append:
E2 = objectify.ElementMaker(annotate=False) anno_tree2 = E2.object( E.name("person"), E.bndbox( E.xmin(100), E.ymin(200), E.xmax(300), E.ymax(400) ), E.difficult(0) ) anno_tree.append(anno_tree2)Above The output becomes:
<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) Use etree and SubElement
##
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(100) etree.SubElement(bndbox, "ymin").text = str(200) etree.SubElement(bndbox, "xmax").text = str(300) etree.SubElement(bndbox, "ymax").text = str(400) etree.SubElement(key_object, "difficult").text = '0' doc = etree.ElementTree(annotation) doc.write(open("test.xml", "w"), pretty_print=True)
Here you can use xpath to directly extract the value of the required element. For example, if you want to get the x, y coordinates of the test.xml file above:
##. #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
The above is the detailed content of Example sharing of how Python uses lxml to read and write xml format files. For more information, please follow other related articles on the PHP Chinese website!