Edit the labels of a xml Annotations dataset

Question

I have a dataset with the following annotations structure:

`<annotation>
<folder>images</folder>
<filename>maksssksksss0.png</filename>
<size>
    <width>512</width>
    <height>366</height>
    <depth>3</depth>
</size>
<segmented>0</segmented>
<object>
    <name>without_mask</name>
    <pose>Unspecified</pose>
    <truncated>0</truncated>
    <occluded>0</occluded>
    <difficult>0</difficult>
    <bndbox>
        <xmin>79</xmin>
        <ymin>105</ymin>
        <xmax>109</xmax>
        <ymax>142</ymax>
    </bndbox>
</object>
<object>
    <name>with_mask</name>
    <pose>Unspecified</pose>
    <truncated>0</truncated>
    <occluded>0</occluded>
    <difficult>0</difficult>
    <bndbox>
        <xmin>185</xmin>
        <ymin>100</ymin>
        <xmax>226</xmax>
        <ymax>144</ymax>
    </bndbox>
</object>
<object>
    <name>without_mask</name>
    <pose>Unspecified</pose>
    <truncated>0</truncated>
    <occluded>0</occluded>
    <difficult>0</difficult>
    <bndbox>
        <xmin>325</xmin>
        <ymin>90</ymin>
        <xmax>360</xmax>
        <ymax>141</ymax>
    </bndbox>
</object>

`

What i wanted to do was to edit all the object labels 'with_mask' to 'face_mask' and to delete all the object labels 'without_mask' from all the dataset files. Any tips on where to begin? libraries and such

Answer 1

Take a look at the lxml library and import etree from there. For searching you can use .findall() and .find(). You also should take a look aswell on how basic xpath constraints work. To remove a element from a tree you can use the .remove function. If you put it all togehter it could look something like this:

from lxml import etree
#Open you xml 
tree = etree.parse("yourxml.xml")
root = tree.getroot()
#Find all objects in your tree
for obj in root.findall('.//object'):
        # Get the first child of the object which is called name
        name = obj.find("name")
        # Use .txt to access the value
        if name.text == "with_mask":
            # Change the text
            obj.attrib["name"] = "face_mask"
        if name.text == "without_mask":
            #Remove the object from the tree
            root.remove(obj)
# Write the tree
with open('yourxml2.xml', 'wb') as f:
    tree.write(f)