walking_svg_layers.py

import xml.dom
import xml.dom.minidom

def childelements(parentnode):
	for node in parentnode.childNodes:
		if node.nodeType != xml.dom.Node.ELEMENT_NODE:
			continue
		yield node

def childlayers(parentnode):
	"""yields child nodes that are elements with the tag name 'g'"""
	for node in childelements(parentnode):
		if node.tagName != "g":
			continue
		yield node

with xml.dom.minidom.parse(svgpath) as dom:
	svg = dom.getElementsByTagName("svg")[0]

	for layer in childlayers(svg):
		pass
	# ...
	
	dom.writexml(outfile)