I was wondering how I can give the paths with labels or tags. Is it possible to set multiple labels/tags to one path? I'd need to give the paths multiple labels or tags for future data processing. I tried the code below but it doesn't work. 

I want to work with a specific layer (called 'Polygon') of multiple paths, including two types of paths: 1, closed polygon paths and 2, paths that are line. I'd like to select all type 2 paths and give them a label called 'boundary'. Since the d string of the closed polygon paths ends up with 'Z',  the d string of the line paths ends up with numbers. I used this method to select the line paths and use item.set() to give the label to the path. 

class Prepare(inkex.EffectExtension):
    
    def find_boundary(self,layer,boundary):
        item = self.svg.get('inkscape:label') 
        if item == layer:
            for child in item.getchidren():
                dstr = child.get('d') 
                if dstr[-1] != 'Z':
                    child.set('label',boundary)

    def effect(self): 
        self.find_boundary('Polygon','boundary')

if __name__ == '__main__':
    Prepare().run()

Labels are really there for the user experience not for coding as such.  They existing the Inkscape namespace, I would not try to manipulate them for assisting coding as such.

A very simple way is to use svg custom data attributes.

https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/data-*#:~:text=The%20data%2D*%20SVG%20attributes,belong%20to%2C%20with%20the%20SVGElement.

As the page points out: 

• Can't start with xml.
• No semicolons (;, U+003A).
• No capital A to Z letters.

I've used them before, very simple and easy.

Hi inklinea,

Thank you for your info. Would you mind providing a simple example?

I read the webpage about data-* and wrote my code, but I couldn't get it to work. 

Thanks!

for item in selection_list:
    item.set('data-czkpanda', 'Hello this is a custom data attribute :)')
    item.set('data-inklinea', 'Another custom data attribute !')

they can be retrieved with item.get and removed using set None

for item in selection_list:
    if item.get('data-czkpanda'):  # if None, is bool False
        item.set('data-czkpanda', None)

Thanks!

Hi, I wonder how I can find ALL the paths with the given attribute within a layer. If I use return, it only return one path and end the loop. 

    def paths_of_dAttr(self,layer,data_attr):
        """Select the paths labeled with the given attribute.
        """
        for item in self.svg:
            if item.get('inkscape:label') == layer:
                paths = item.getchildren()
                for path in paths:
                    if path.get(data_attr):
                       return path

Hi, I wonder how I can find ALL the paths with the given attribute within a layer. If I use return, it only return one path and end the loop. 

    def paths_of_dAttr(self,layer,data_attr):
        """Select the paths labeled with the given attribute.
        """
        for item in self.svg:
            if item.get('inkscape:label') == layer:
                paths = item.getchildren()
                for path in paths:
                    if path.get(data_attr):
                       return path

I solved the problem using xpath method.