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# Source code for networkx.readwrite.gexf

    """Read and write graphs in GEXF format.

    .. warning::
        This parser uses the standard xml library present in Python, which is
        insecure - see :external+python:mod:`xml` for additional information.
        Only parse GEFX files you trust.

    GEXF (Graph Exchange XML Format) is a language for describing complex
    network structures, their associated data and dynamics.

    This implementation does not support mixed graphs (directed and
    undirected edges together).

    Format
    ------
    GEXF is an XML format.  See http://gexf.net/schema.html for the
    specification and http://gexf.net/basic.html for examples.
    """

    import itertools
    import time
    from xml.etree.ElementTree import (
        Element,
        ElementTree,
        SubElement,
        register_namespace,
        tostring,
    )

    import networkx as nx
    from networkx.utils import open_file

    __all__ = ["write_gexf", "read_gexf", "relabel_gexf_graph", "generate_gexf"]

    @open_file(1, mode="wb")
    def write_gexf(G, path, encoding="utf-8", prettyprint=True, version="1.2draft"):
        """Write G in GEXF format to path.

        "GEXF (Graph Exchange XML Format) is a language for describing
        complex networks structures, their associated data and dynamics" [1]_.

        Node attributes are checked according to the version of the GEXF
        schemas used for parameters which are not user defined,
        e.g. visualization 'viz' [2]_. See example for usage.

        Parameters
        ----------
        G : graph
           A NetworkX graph
        path : file or string
           File or file name to write.
           File names ending in .gz or .bz2 will be compressed.
        encoding : string (optional, default: 'utf-8')
           Encoding for text data.
        prettyprint : bool (optional, default: True)
           If True use line breaks and indenting in output XML.
        version: string (optional, default: '1.2draft')
           The version of GEXF to be used for nodes attributes checking

        Examples
        --------
        >>> G = nx.path_graph(4)
        >>> nx.write_gexf(G, "test.gexf")

        # visualization data
        >>> G.nodes[0]["viz"] = {"size": 54}
        >>> G.nodes[0]["viz"]["position"] = {"x": 0, "y": 1}
        >>> G.nodes[0]["viz"]["color"] = {"r": 0, "g": 0, "b": 256}

        Notes
        -----
        This implementation does not support mixed graphs (directed and undirected
        edges together).

        The node id attribute is set to be the string of the node label.
        If you want to specify an id use set it as node data, e.g.
        node['a']['id']=1 to set the id of node 'a' to 1.

        References
        ----------
        .. [1] GEXF File Format, http://gexf.net/
        .. [2] GEXF schema, http://gexf.net/schema.html
        """
        writer = GEXFWriter(encoding=encoding, prettyprint=prettyprint, version=version)
        writer.add_graph(G)
        writer.write(path)

    def generate_gexf(G, encoding="utf-8", prettyprint=True, version="1.2draft"):
        """Generate lines of GEXF format representation of G.

        "GEXF (Graph Exchange XML Format) is a language for describing
        complex networks structures, their associated data and dynamics" [1]_.

        Parameters
        ----------
        G : graph
        A NetworkX graph
        encoding : string (optional, default: 'utf-8')
        Encoding for text data.
        prettyprint : bool (optional, default: True)
        If True use line breaks and indenting in output XML.
        version : string (default: 1.2draft)
        Version of GEFX File Format (see http://gexf.net/schema.html)
        Supported values: "1.1draft", "1.2draft"

        Examples
        --------
        >>> G = nx.path_graph(4)
        >>> linefeed = chr(10)  # linefeed=\n
        >>> s = linefeed.join(nx.generate_gexf(G))
        >>> for line in nx.generate_gexf(G):  # doctest: +SKIP
        ...     print(line)

        Notes
        -----
        This implementation does not support mixed graphs (directed and undirected
        edges together).

        The node id attribute is set to be the string of the node label.
        If you want to specify an id use set it as node data, e.g.
        node['a']['id']=1 to set the id of node 'a' to 1.

        References
        ----------
        .. [1] GEXF File Format, https://gephi.org/gexf/format/
        """
        writer = GEXFWriter(encoding=encoding, prettyprint=prettyprint, version=version)
        writer.add_graph(G)
        yield from str(writer).splitlines()

    @open_file(0, mode="rb")
    @nx._dispatchable(graphs=None, returns_graph=True)
    def read_gexf(path, node_type=None, relabel=False, version="1.2draft"):
        """Read graph in GEXF format from path.

        "GEXF (Graph Exchange XML Format) is a language for describing
        complex networks structures, their associated data and dynamics" [1]_.

        Parameters
        ----------
        path : file or string
           File or file name to read.
           File names ending in .gz or .bz2 will be decompressed.
        node_type: Python type (default: None)
           Convert node ids to this type if not None.
        relabel : bool (default: False)
           If True relabel the nodes to use the GEXF node "label" attribute
           instead of the node "id" attribute as the NetworkX node label.
        version : string (default: 1.2draft)
        Version of GEFX File Format (see http://gexf.net/schema.html)
           Supported values: "1.1draft", "1.2draft"

        Returns
        -------
        graph: NetworkX graph
            If no parallel edges are found a Graph or DiGraph is returned.
            Otherwise a MultiGraph or MultiDiGraph is returned.

        Notes
        -----
        This implementation does not support mixed graphs (directed and undirected
        edges together).

        References
        ----------
        .. [1] GEXF File Format, http://gexf.net/
        """
        reader = GEXFReader(node_type=node_type, version=version)
        if relabel:
            G = relabel_gexf_graph(reader(path))
        else:
            G = reader(path)
        return G

    class GEXF:
        versions = {
            "1.1draft": {
                "NS_GEXF": "http://www.gexf.net/1.1draft",
                "NS_VIZ": "http://www.gexf.net/1.1draft/viz",
                "NS_XSI": "http://www.w3.org/2001/XMLSchema-instance",
                "SCHEMALOCATION": " ".join(
                    [
                        "http://www.gexf.net/1.1draft",
                        "http://www.gexf.net/1.1draft/gexf.xsd",
                    ]
                ),
                "VERSION": "1.1",
            },
            "1.2draft": {
                "NS_GEXF": "http://www.gexf.net/1.2draft",
                "NS_VIZ": "http://www.gexf.net/1.2draft/viz",
                "NS_XSI": "http://www.w3.org/2001/XMLSchema-instance",
                "SCHEMALOCATION": " ".join(
                    [
                        "http://www.gexf.net/1.2draft",
                        "http://www.gexf.net/1.2draft/gexf.xsd",
                    ]
                ),
                "VERSION": "1.2",
            },
        }

        def construct_types(self):
            types = [
                (int, "integer"),
                (float, "float"),
                (float, "double"),
                (bool, "boolean"),
                (list, "string"),
                (dict, "string"),
                (int, "long"),
                (str, "liststring"),
                (str, "anyURI"),
                (str, "string"),
            ]

            # These additions to types allow writing numpy types
            try:
                import numpy as np
            except ImportError:
                pass
            else:
                # prepend so that python types are created upon read (last entry wins)
                types = [
                    (np.float64, "float"),
                    (np.float32, "float"),
                    (np.float16, "float"),
                    (np.int_, "int"),
                    (np.int8, "int"),
                    (np.int16, "int"),
                    (np.int32, "int"),
                    (np.int64, "int"),
                    (np.uint8, "int"),
                    (np.uint16, "int"),
                    (np.uint32, "int"),
                    (np.uint64, "int"),
                    (np.int_, "int"),
                    (np.intc, "int"),
                    (np.intp, "int"),
                ] + types

            self.xml_type = dict(types)
            self.python_type = dict(reversed(a) for a in types)

        # http://www.w3.org/TR/xmlschema-2/#boolean
        convert_bool = {
            "true": True,
            "false": False,
            "True": True,
            "False": False,
            "0": False,
            0: False,
            "1": True,
            1: True,
        }

        def set_version(self, version):
            d = self.versions.get(version)
            if d is None:
                raise nx.NetworkXError(f"Unknown GEXF version {version}.")
            self.NS_GEXF = d["NS_GEXF"]
            self.NS_VIZ = d["NS_VIZ"]
            self.NS_XSI = d["NS_XSI"]
            self.SCHEMALOCATION = d["SCHEMALOCATION"]
            self.VERSION = d["VERSION"]
            self.version = version

    class GEXFWriter(GEXF):
        # class for writing GEXF format files
        # use write_gexf() function
        def __init__(
            self, graph=None, encoding="utf-8", prettyprint=True, version="1.2draft"
        ):
            self.construct_types()
            self.prettyprint = prettyprint
            self.encoding = encoding
            self.set_version(version)
            self.xml = Element(
                "gexf",
                {
                    "xmlns": self.NS_GEXF,
                    "xmlns:xsi": self.NS_XSI,
                    "xsi:schemaLocation": self.SCHEMALOCATION,
                    "version": self.VERSION,
                },
            )

            # Make meta element a non-graph element
            # Also add lastmodifieddate as attribute, not tag
            meta_element = Element("meta")
            subelement_text = f"NetworkX {nx.__version__}"
            SubElement(meta_element, "creator").text = subelement_text
            meta_element.set("lastmodifieddate", time.strftime("%Y-%m-%d"))
            self.xml.append(meta_element)

            register_namespace("viz", self.NS_VIZ)

            # counters for edge and attribute identifiers
            self.edge_id = itertools.count()
            self.attr_id = itertools.count()
            self.all_edge_ids = set()
            # default attributes are stored in dictionaries
            self.attr = {}
            self.attr["node"] = {}
            self.attr["edge"] = {}
            self.attr["node"]["dynamic"] = {}
            self.attr["node"]["static"] = {}
            self.attr["edge"]["dynamic"] = {}
            self.attr["edge"]["static"] = {}

            if graph is not None:
                self.add_graph(graph)

        def __str__(self):
            if self.prettyprint:
                self.indent(self.xml)
            s = tostring(self.xml).decode(self.encoding)
            return s

        def add_graph(self, G):
            # first pass through G collecting edge ids
            for u, v, dd in G.edges(data=True):
                eid = dd.get("id")
                if eid is not None:
                    self.all_edge_ids.add(str(eid))
            # set graph attributes
            if G.graph.get("mode") == "dynamic":
                mode = "dynamic"
            else:
                mode = "static"
            # Add a graph element to the XML
            if G.is_directed():
                default = "directed"
            else:
                default = "undirected"
            name = G.graph.get("name", "")
            graph_element = Element("graph", defaultedgetype=default, mode=mode, name=name)
            self.graph_element = graph_element
            self.add_nodes(G, graph_element)
            self.add_edges(G, graph_element)
            self.xml.append(graph_element)

        def add_nodes(self, G, graph_element):
            nodes_element = Element("nodes")
            for node, data in G.nodes(data=True):
                node_data = data.copy()
                node_id = str(node_data.pop("id", node))
                kw = {"id": node_id}
                label = str(node_data.pop("label", node))
                kw["label"] = label
                try:
                    pid = node_data.pop("pid")
                    kw["pid"] = str(pid)
                except KeyError:
                    pass
                try:
                    start = node_data.pop("start")
                    kw["start"] = str(start)
                    self.alter_graph_mode_timeformat(start)
                except KeyError:
                    pass
                try:
                    end = node_data.pop("end")
                    kw["end"] = str(end)
                    self.alter_graph_mode_timeformat(end)
                except KeyError:
                    pass
                # add node element with attributes
                node_element = Element("node", **kw)
                # add node element and attr subelements
                default = G.graph.get("node_default", {})
                node_data = self.add_parents(node_element, node_data)
                if self.VERSION == "1.1":
                    node_data = self.add_slices(node_element, node_data)
                else:
                    node_data = self.add_spells(node_element, node_data)
                node_data = self.add_viz(node_element, node_data)
                node_data = self.add_attributes("node", node_element, node_data, default)
                nodes_element.append(node_element)
            graph_element.append(nodes_element)

        def add_edges(self, G, graph_element):
            def edge_key_data(G):
                # helper function to unify multigraph and graph edge iterator
                if G.is_multigraph():
                    for u, v, key, data in G.edges(data=True, keys=True):
                        edge_data = data.copy()
                        edge_data.update(key=key)
                        edge_id = edge_data.pop("id", None)
                        if edge_id is None:
                            edge_id = next(self.edge_id)
                            while str(edge_id) in self.all_edge_ids:
                                edge_id = next(self.edge_id)
                            self.all_edge_ids.add(str(edge_id))
                        yield u, v, edge_id, edge_data
                else:
                    for u, v, data in G.edges(data=True):
                        edge_data = data.copy()
                        edge_id = edge_data.pop("id", None)
                        if edge_id is None:
                            edge_id = next(self.edge_id)
                            while str(edge_id) in self.all_edge_ids:
                                edge_id = next(self.edge_id)
                            self.all_edge_ids.add(str(edge_id))
                        yield u, v, edge_id, edge_data

            edges_element = Element("edges")
            for u, v, key, edge_data in edge_key_data(G):
                kw = {"id": str(key)}
                try:
                    edge_label = edge_data.pop("label")
                    kw["label"] = str(edge_label)
                except KeyError:
                    pass
                try:
                    edge_weight = edge_data.pop("weight")
                    kw["weight"] = str(edge_weight)
                except KeyError:
                    pass
                try:
                    edge_type = edge_data.pop("type")
                    kw["type"] = str(edge_type)
                except KeyError:
                    pass
                try:
                    start = edge_data.pop("start")
                    kw["start"] = str(start)
                    self.alter_graph_mode_timeformat(start)
                except KeyError:
                    pass
                try:
                    end = edge_data.pop("end")
                    kw["end"] = str(end)
                    self.alter_graph_mode_timeformat(end)
                except KeyError:
                    pass
                source_id = str(G.nodes[u].get("id", u))
                target_id = str(G.nodes[v].get("id", v))
                edge_element = Element("edge", source=source_id, target=target_id, **kw)
                default = G.graph.get("edge_default", {})
                if self.VERSION == "1.1":
                    edge_data = self.add_slices(edge_element, edge_data)
                else:
                    edge_data = self.add_spells(edge_element, edge_data)
                edge_data = self.add_viz(edge_element, edge_data)
                edge_data = self.add_attributes("edge", edge_element, edge_data, default)
                edges_element.append(edge_element)
            graph_element.append(edges_element)

        def add_attributes(self, node_or_edge, xml_obj, data, default):
            # Add attrvalues to node or edge
            attvalues = Element("attvalues")
            if len(data) == 0:
                return data
            mode = "static"
            for k, v in data.items():
                # rename generic multigraph key to avoid any name conflict
                if k == "key":
                    k = "networkx_key"
                val_type = type(v)
                if val_type not in self.xml_type:
                    raise TypeError(f"attribute value type is not allowed: {val_type}")
                if isinstance(v, list):
                    # dynamic data
                    for val, start, end in v:
                        val_type = type(val)
                        if start is not None or end is not None:
                            mode = "dynamic"
                            self.alter_graph_mode_timeformat(start)
                            self.alter_graph_mode_timeformat(end)
                            break
                    attr_id = self.get_attr_id(
                        str(k), self.xml_type[val_type], node_or_edge, default, mode
                    )
                    for val, start, end in v:
                        e = Element("attvalue")
                        e.attrib["for"] = attr_id
                        e.attrib["value"] = str(val)
                        # Handle nan, inf, -inf differently
                        if val_type == float:
                            if e.attrib["value"] == "inf":
                                e.attrib["value"] = "INF"
                            elif e.attrib["value"] == "nan":
                                e.attrib["value"] = "NaN"
                            elif e.attrib["value"] == "-inf":
                                e.attrib["value"] = "-INF"
                        if start is not None:
                            e.attrib["start"] = str(start)
                        if end is not None:
                            e.attrib["end"] = str(end)
                        attvalues.append(e)
                else:
                    # static data
                    mode = "static"
                    attr_id = self.get_attr_id(
                        str(k), self.xml_type[val_type], node_or_edge, default, mode
                    )
                    e = Element("attvalue")
                    e.attrib["for"] = attr_id
                    if isinstance(v, bool):
                        e.attrib["value"] = str(v).lower()
                    else:
                        e.attrib["value"] = str(v)
                        # Handle float nan, inf, -inf differently
                        if val_type == float:
                            if e.attrib["value"] == "inf":
                                e.attrib["value"] = "INF"
                            elif e.attrib["value"] == "nan":
                                e.attrib["value"] = "NaN"
                            elif e.attrib["value"] == "-inf":
                                e.attrib["value"] = "-INF"
                    attvalues.append(e)
            xml_obj.append(attvalues)
            return data

        def get_attr_id(self, title, attr_type, edge_or_node, default, mode):
            # find the id of the attribute or generate a new id
            try:
                return self.attr[edge_or_node][mode][title]
            except KeyError:
                # generate new id
                new_id = str(next(self.attr_id))
                self.attr[edge_or_node][mode][title] = new_id
                attr_kwargs = {"id": new_id, "title": title, "type": attr_type}
                attribute = Element("attribute", **attr_kwargs)
                # add subelement for data default value if present
                default_title = default.get(title)
                if default_title is not None:
                    default_element = Element("default")
                    default_element.text = str(default_title)
                    attribute.append(default_element)
                # new insert it into the XML
                attributes_element = None
                for a in self.graph_element.findall("attributes"):
                    # find existing attributes element by class and mode
                    a_class = a.get("class")
                    a_mode = a.get("mode", "static")
                    if a_class == edge_or_node and a_mode == mode:
                        attributes_element = a
                if attributes_element is None:
                    # create new attributes element
                    attr_kwargs = {"mode": mode, "class": edge_or_node}
                    attributes_element = Element("attributes", **attr_kwargs)
                    self.graph_element.insert(0, attributes_element)
                attributes_element.append(attribute)
            return new_id

        def add_viz(self, element, node_data):
            viz = node_data.pop("viz", False)
            if viz:
                color = viz.get("color")
                if color is not None:
                    if self.VERSION == "1.1":
                        e = Element(
                            f"{{{self.NS_VIZ}}}color",
                            r=str(color.get("r")),
                            g=str(color.get("g")),
                            b=str(color.get("b")),
                        )
                    else:
                        e = Element(
                            f"{{{self.NS_VIZ}}}color",
                            r=str(color.get("r")),
                            g=str(color.get("g")),
                            b=str(color.get("b")),
                            a=str(color.get("a", 1.0)),
                        )
                    element.append(e)

                size = viz.get("size")
                if size is not None:
                    e = Element(f"{{{self.NS_VIZ}}}size", value=str(size))
                    element.append(e)

                thickness = viz.get("thickness")
                if thickness is not None:
                    e = Element(f"{{{self.NS_VIZ}}}thickness", value=str(thickness))
                    element.append(e)

                shape = viz.get("shape")
                if shape is not None:
                    if shape.startswith("http"):
                        e = Element(
                            f"{{{self.NS_VIZ}}}shape", value="image", uri=str(shape)
                        )
                    else:
                        e = Element(f"{{{self.NS_VIZ}}}shape", value=str(shape))
                    element.append(e)

                position = viz.get("position")
                if position is not None:
                    e = Element(
                        f"{{{self.NS_VIZ}}}position",
                        x=str(position.get("x")),
                        y=str(position.get("y")),
                        z=str(position.get("z")),
                    )
                    element.append(e)
            return node_data

        def add_parents(self, node_element, node_data):
            parents = node_data.pop("parents", False)
            if parents:
                parents_element = Element("parents")
                for p in parents:
                    e = Element("parent")
                    e.attrib["for"] = str(p)
                    parents_element.append(e)
                node_element.append(parents_element)
            return node_data

        def add_slices(self, node_or_edge_element, node_or_edge_data):
            slices = node_or_edge_data.pop("slices", False)
            if slices:
                slices_element = Element("slices")
                for start, end in slices:
                    e = Element("slice", start=str(start), end=str(end))
                    slices_element.append(e)
                node_or_edge_element.append(slices_element)
            return node_or_edge_data

        def add_spells(self, node_or_edge_element, node_or_edge_data):
            spells = node_or_edge_data.pop("spells", False)
            if spells:
                spells_element = Element("spells")
                for start, end in spells:
                    e = Element("spell")
                    if start is not None:
                        e.attrib["start"] = str(start)
                        self.alter_graph_mode_timeformat(start)
                    if end is not None:
                        e.attrib["end"] = str(end)
                        self.alter_graph_mode_timeformat(end)
                    spells_element.append(e)
                node_or_edge_element.append(spells_element)
            return node_or_edge_data

        def alter_graph_mode_timeformat(self, start_or_end):
            # If 'start' or 'end' appears, alter Graph mode to dynamic and
            # set timeformat
            if self.graph_element.get("mode") == "static":
                if start_or_end is not None:
                    if isinstance(start_or_end, str):
                        timeformat = "date"
                    elif isinstance(start_or_end, float):
                        timeformat = "double"
                    elif isinstance(start_or_end, int):
                        timeformat = "long"
                    else:
                        raise nx.NetworkXError(
                            "timeformat should be of the type int, float or str"
                        )
                    self.graph_element.set("timeformat", timeformat)
                    self.graph_element.set("mode", "dynamic")

        def write(self, fh):
            # Serialize graph G in GEXF to the open fh
            if self.prettyprint:
                self.indent(self.xml)
            document = ElementTree(self.xml)
            document.write(fh, encoding=self.encoding, xml_declaration=True)

        def indent(self, elem, level=0):
            # in-place prettyprint formatter
            i = "\n" + "  " * level
            if len(elem):
                if not elem.text or not elem.text.strip():
                    elem.text = i + "  "
                if not elem.tail or not elem.tail.strip():
                    elem.tail = i
                for elem in elem:
                    self.indent(elem, level + 1)
                if not elem.tail or not elem.tail.strip():
                    elem.tail = i
            else:
                if level and (not elem.tail or not elem.tail.strip()):
                    elem.tail = i

    class GEXFReader(GEXF):
        # Class to read GEXF format files
        # use read_gexf() function
        def __init__(self, node_type=None, version="1.2draft"):
            self.construct_types()
            self.node_type = node_type
            # assume simple graph and test for multigraph on read
            self.simple_graph = True
            self.set_version(version)

        def __call__(self, stream):
            self.xml = ElementTree(file=stream)
            g = self.xml.find(f"{{{self.NS_GEXF}}}graph")
            if g is not None:
                return self.make_graph(g)
            # try all the versions
            for version in self.versions:
                self.set_version(version)
                g = self.xml.find(f"{{{self.NS_GEXF}}}graph")
                if g is not None:
                    return self.make_graph(g)
            raise nx.NetworkXError("No <graph> element in GEXF file.")

        def make_graph(self, graph_xml):
            # start with empty DiGraph or MultiDiGraph
            edgedefault = graph_xml.get("defaultedgetype", None)
            if edgedefault == "directed":
                G = nx.MultiDiGraph()
            else:
                G = nx.MultiGraph()

            # graph attributes
            graph_name = graph_xml.get("name", "")
            if graph_name != "":
                G.graph["name"] = graph_name
            graph_start = graph_xml.get("start")
            if graph_start is not None:
                G.graph["start"] = graph_start
            graph_end = graph_xml.get("end")
            if graph_end is not None:
                G.graph["end"] = graph_end
            graph_mode = graph_xml.get("mode", "")
            if graph_mode == "dynamic":
                G.graph["mode"] = "dynamic"
            else:
                G.graph["mode"] = "static"

            # timeformat
            self.timeformat = graph_xml.get("timeformat")
            if self.timeformat == "date":
                self.timeformat = "string"

            # node and edge attributes
            attributes_elements = graph_xml.findall(f"{{{self.NS_GEXF}}}attributes")
            # dictionaries to hold attributes and attribute defaults
            node_attr = {}
            node_default = {}
            edge_attr = {}
            edge_default = {}
            for a in attributes_elements:
                attr_class = a.get("class")
                if attr_class == "node":
                    na, nd = self.find_gexf_attributes(a)
                    node_attr.update(na)
                    node_default.update(nd)
                    G.graph["node_default"] = node_default
                elif attr_class == "edge":
                    ea, ed = self.find_gexf_attributes(a)
                    edge_attr.update(ea)
                    edge_default.update(ed)
                    G.graph["edge_default"] = edge_default
                else:
                    raise  # unknown attribute class

            # Hack to handle Gephi0.7beta bug
            # add weight attribute
            ea = {"weight": {"type": "double", "mode": "static", "title": "weight"}}
            ed = {}
            edge_attr.update(ea)
            edge_default.update(ed)
            G.graph["edge_default"] = edge_default

            # add nodes
            nodes_element = graph_xml.find(f"{{{self.NS_GEXF}}}nodes")
            if nodes_element is not None:
                for node_xml in nodes_element.findall(f"{{{self.NS_GEXF}}}node"):
                    self.add_node(G, node_xml, node_attr)

            # add edges
            edges_element = graph_xml.find(f"{{{self.NS_GEXF}}}edges")
            if edges_element is not None:
                for edge_xml in edges_element.findall(f"{{{self.NS_GEXF}}}edge"):
                    self.add_edge(G, edge_xml, edge_attr)

            # switch to Graph or DiGraph if no parallel edges were found.
            if self.simple_graph:
                if G.is_directed():
                    G = nx.DiGraph(G)
                else:
                    G = nx.Graph(G)
            return G

        def add_node(self, G, node_xml, node_attr, node_pid=None):
            # add a single node with attributes to the graph

            # get attributes and subattributues for node
            data = self.decode_attr_elements(node_attr, node_xml)
            data = self.add_parents(data, node_xml)  # add any parents
            if self.VERSION == "1.1":
                data = self.add_slices(data, node_xml)  # add slices
            else:
                data = self.add_spells(data, node_xml)  # add spells
            data = self.add_viz(data, node_xml)  # add viz
            data = self.add_start_end(data, node_xml)  # add start/end

            # find the node id and cast it to the appropriate type
            node_id = node_xml.get("id")
            if self.node_type is not None:
                node_id = self.node_type(node_id)

            # every node should have a label
            node_label = node_xml.get("label")
            data["label"] = node_label

            # parent node id
            node_pid = node_xml.get("pid", node_pid)
            if node_pid is not None:
                data["pid"] = node_pid

            # check for subnodes, recursive
            subnodes = node_xml.find(f"{{{self.NS_GEXF}}}nodes")
            if subnodes is not None:
                for node_xml in subnodes.findall(f"{{{self.NS_GEXF}}}node"):
                    self.add_node(G, node_xml, node_attr, node_pid=node_id)

            G.add_node(node_id, **data)

        def add_start_end(self, data, xml):
            # start and end times
            ttype = self.timeformat
            node_start = xml.get("start")
            if node_start is not None:
                data["start"] = self.python_type[ttype](node_start)
            node_end = xml.get("end")
            if node_end is not None:
                data["end"] = self.python_type[ttype](node_end)
            return data

        def add_viz(self, data, node_xml):
            # add viz element for node
            viz = {}
            color = node_xml.find(f"{{{self.NS_VIZ}}}color")
            if color is not None:
                if self.VERSION == "1.1":
                    viz["color"] = {
                        "r": int(color.get("r")),
                        "g": int(color.get("g")),
                        "b": int(color.get("b")),
                    }
                else:
                    viz["color"] = {
                        "r": int(color.get("r")),
                        "g": int(color.get("g")),
                        "b": int(color.get("b")),
                        "a": float(color.get("a", 1)),
                    }

            size = node_xml.find(f"{{{self.NS_VIZ}}}size")
            if size is not None:
                viz["size"] = float(size.get("value"))

            thickness = node_xml.find(f"{{{self.NS_VIZ}}}thickness")
            if thickness is not None:
                viz["thickness"] = float(thickness.get("value"))

            shape = node_xml.find(f"{{{self.NS_VIZ}}}shape")
            if shape is not None:
                viz["shape"] = shape.get("shape")
                if viz["shape"] == "image":
                    viz["shape"] = shape.get("uri")

            position = node_xml.find(f"{{{self.NS_VIZ}}}position")
            if position is not None:
                viz["position"] = {
                    "x": float(position.get("x", 0)),
                    "y": float(position.get("y", 0)),
                    "z": float(position.get("z", 0)),
                }

            if len(viz) > 0:
                data["viz"] = viz
            return data

        def add_parents(self, data, node_xml):
            parents_element = node_xml.find(f"{{{self.NS_GEXF}}}parents")
            if parents_element is not None:
                data["parents"] = []
                for p in parents_element.findall(f"{{{self.NS_GEXF}}}parent"):
                    parent = p.get("for")
                    data["parents"].append(parent)
            return data

        def add_slices(self, data, node_or_edge_xml):
            slices_element = node_or_edge_xml.find(f"{{{self.NS_GEXF}}}slices")
            if slices_element is not None:
                data["slices"] = []
                for s in slices_element.findall(f"{{{self.NS_GEXF}}}slice"):
                    start = s.get("start")
                    end = s.get("end")
                    data["slices"].append((start, end))
            return data

        def add_spells(self, data, node_or_edge_xml):
            spells_element = node_or_edge_xml.find(f"{{{self.NS_GEXF}}}spells")
            if spells_element is not None:
                data["spells"] = []
                ttype = self.timeformat
                for s in spells_element.findall(f"{{{self.NS_GEXF}}}spell"):
                    start = self.python_type[ttype](s.get("start"))
                    end = self.python_type[ttype](s.get("end"))
                    data["spells"].append((start, end))
            return data

        def add_edge(self, G, edge_element, edge_attr):
            # add an edge to the graph

            # raise error if we find mixed directed and undirected edges
            edge_direction = edge_element.get("type")
            if G.is_directed() and edge_direction == "undirected":
                raise nx.NetworkXError("Undirected edge found in directed graph.")
            if (not G.is_directed()) and edge_direction == "directed":
                raise nx.NetworkXError("Directed edge found in undirected graph.")

            # Get source and target and recast type if required
            source = edge_element.get("source")
            target = edge_element.get("target")
            if self.node_type is not None:
                source = self.node_type(source)
                target = self.node_type(target)

            data = self.decode_attr_elements(edge_attr, edge_element)
            data = self.add_start_end(data, edge_element)

            if self.VERSION == "1.1":
                data = self.add_slices(data, edge_element)  # add slices
            else:
                data = self.add_spells(data, edge_element)  # add spells

            # GEXF stores edge ids as an attribute
            # NetworkX uses them as keys in multigraphs
            # if networkx_key is not specified as an attribute
            edge_id = edge_element.get("id")
            if edge_id is not None:
                data["id"] = edge_id

            # check if there is a 'multigraph_key' and use that as edge_id
            multigraph_key = data.pop("networkx_key", None)
            if multigraph_key is not None:
                edge_id = multigraph_key

            weight = edge_element.get("weight")
            if weight is not None:
                data["weight"] = float(weight)

            edge_label = edge_element.get("label")
            if edge_label is not None:
                data["label"] = edge_label

            if G.has_edge(source, target):
                # seen this edge before - this is a multigraph
                self.simple_graph = False
            G.add_edge(source, target, key=edge_id, **data)
            if edge_direction == "mutual":
                G.add_edge(target, source, key=edge_id, **data)

        def decode_attr_elements(self, gexf_keys, obj_xml):
            # Use the key information to decode the attr XML
            attr = {}
            # look for outer '<attvalues>' element
            attr_element = obj_xml.find(f"{{{self.NS_GEXF}}}attvalues")
            if attr_element is not None:
                # loop over <attvalue> elements
                for a in attr_element.findall(f"{{{self.NS_GEXF}}}attvalue"):
                    key = a.get("for")  # for is required
                    try:  # should be in our gexf_keys dictionary
                        title = gexf_keys[key]["title"]
                    except KeyError as err:
                        raise nx.NetworkXError(f"No attribute defined for={key}.") from err
                    atype = gexf_keys[key]["type"]
                    value = a.get("value")
                    if atype == "boolean":
                        value = self.convert_bool[value]
                    else:
                        value = self.python_type[atype](value)
                    if gexf_keys[key]["mode"] == "dynamic":
                        # for dynamic graphs use list of three-tuples
                        # [(value1,start1,end1), (value2,start2,end2), etc]
                        ttype = self.timeformat
                        start = self.python_type[ttype](a.get("start"))
                        end = self.python_type[ttype](a.get("end"))
                        if title in attr:
                            attr[title].append((value, start, end))
                        else:
                            attr[title] = [(value, start, end)]
                    else:
                        # for static graphs just assign the value
                        attr[title] = value
            return attr

        def find_gexf_attributes(self, attributes_element):
            # Extract all the attributes and defaults
            attrs = {}
            defaults = {}
            mode = attributes_element.get("mode")
            for k in attributes_element.findall(f"{{{self.NS_GEXF}}}attribute"):
                attr_id = k.get("id")
                title = k.get("title")
                atype = k.get("type")
                attrs[attr_id] = {"title": title, "type": atype, "mode": mode}
                # check for the 'default' subelement of key element and add
                default = k.find(f"{{{self.NS_GEXF}}}default")
                if default is not None:
                    if atype == "boolean":
                        value = self.convert_bool[default.text]
                    else:
                        value = self.python_type[atype](default.text)
                    defaults[title] = value
            return attrs, defaults

    def relabel_gexf_graph(G):
        """Relabel graph using "label" node keyword for node label.

        Parameters
        ----------
        G : graph
           A NetworkX graph read from GEXF data

        Returns
        -------
        H : graph
          A NetworkX graph with relabeled nodes

        Raises
        ------
        NetworkXError
            If node labels are missing or not unique while relabel=True.

        Notes
        -----
        This function relabels the nodes in a NetworkX graph with the
        "label" attribute.  It also handles relabeling the specific GEXF
        node attributes "parents", and "pid".
        """
        # build mapping of node labels, do some error checking
        try:
            mapping = [(u, G.nodes[u]["label"]) for u in G]
        except KeyError as err:
            raise nx.NetworkXError(
                "Failed to relabel nodes: missing node labels found. Use relabel=False."
            ) from err
        x, y = zip(*mapping)
        if len(set(y)) != len(G):
            raise nx.NetworkXError(
                "Failed to relabel nodes: "
                "duplicate node labels found. "
                "Use relabel=False."
            )
        mapping = dict(mapping)
        H = nx.relabel_nodes(G, mapping)
        # relabel attributes
        for n in G:
            m = mapping[n]
            H.nodes[m]["id"] = n
            H.nodes[m].pop("label")
            if "pid" in H.nodes[m]:
                H.nodes[m]["pid"] = mapping[G.nodes[n]["pid"]]
            if "parents" in H.nodes[m]:
                H.nodes[m]["parents"] = [mapping[p] for p in G.nodes[n]["parents"]]
        return H