joshwolff1/gremlin-python_abstractions.py

## gremlin-python_abstractions.py
from gremlin_python.structure.graph import Graph
from gremlin_python.process.graph_traversal import __

# I use a property instead of directly setting the ID because I could not get it to work, and this works
# just as well for now. I'd imagine setting the id directly is better for runtime.
# If you figure out how to set the id directly with gremlin-python, feel free to make a pull request and I'll merge it.
IDENTIFICATION_PROPERTY = 'identification'
WEIGHT_PROPERTY = 'weight'

"""
Feel free to use this for gremlin-python, which does not have a lot of clear documentation on the differences between
itself and Groovy, even though there are many.

This gist offers some abstracted functions to make starting with gremlin-python easy.

To connect to AWS Neptune with gremlin, you have to use a VPC - you can ssh in your console for example,
but cannot run a script from PyCharm.

See how to connect to AWS Neptune from AWS Lambda, which reduces running database operations to basically running a
PyCharm script, for testing.
https://docs.aws.amazon.com/neptune/latest/userguide/get-started-cfn-lambda.html
"""


def remove_vertex_from_graph(v, g):
    """
    remove_node_from_graph
    :param v: the vertex to remove
    :param g: the graph
    :return: -
    """
    g.V(v).drop().iterate()


def add_vertex_to_graph(ident, label, g):
    """
    add_node_to_graph
    :param ident: the id for the new vertex
    :param label: the label classifying the vertex
    :param g: the graph
    :return: -
    """
    return g.addV(label).property(IDENTIFICATION_PROPERTY, str(ident)).next()


def remove_edge_from_graph(edge, g):
    """
    remove_node_from_graph
    :param edge: the edge to remove
    :param g: the graph
    :return: -
    """
    g.E(edge).drop().iterate()


def add_edge_to_graph(v1, v2, label, g):
    """
    connect_edges
    :param v1: vertex 1
    :param v2: vertex 2
    :param relation: a string label for the edge
    :param g: the graph
    :return: -
    """
    return g.V(v1).addE(label).to(g.V(v2)).next()


def update_edge_weight(edge, increment, g):
    """
    update_edge_weight
    :param edge: the edge to increment
    :param increment: the amount by which to increment the weight
    :return: -
    """
    g.E(edge).property(WEIGHT_PROPERTY, increment + get_edge_weight(edge, g).next())


def get_edge_weight(edge, g):
    """
    get_edge_weight
    :param edge: the edge, of the type returned by get_edge
    :return: the weight of the given edge
    """
    values = g.E(edge).valueMap().next()
    return values.get(WEIGHT_PROPERTY, 0)


def get_edge(v1_id, v2_id, label, g):
    """
    get_edge
    :param v1_id: the string id of the first vertex
    :param v2_id: the string id of the second vertex
    :param label: string label of the edge, such as 'knows'
    :param g: the graph
    :return: the edge
    """
    try:
        return g.V(v1_id).outE(label).where(__.inV().where(__.hasId(v2_id))).next()
    except:
        # The edge does not exist.
        return None


def get_vertex(ident, label, g):
    """
    get_vertex
    :param ident: string id of the vertex
    :param label: the label of the vertex
    :param g: the graph
    :return: the vertex
    """
    try:
        return g.V().hasLabel(label).has(IDENTIFICATION_PROPERTY, ident).next()
    except:
        # The vertex does not exist
        return None


def get_vertices_going_out_from_vertex_with_edge_label(v, g, label=None):
    """
    get_vertices_going_out_from_vertex_with_edge_label
    :param v: the vertex
    :param g: the graph
    :param label: optional parameter - if defined, returns all vertices connected to the given vertex via an edge of the
    defined label. If not defined, returns all vertices going out from the specified vertex
    :return: a list of vertices
    """
    if label is None:
        # outE gets edges going out
        return g.V(v).out().fold().next()
    else:
        return g.V(v).out(label).fold().next()


def get_vertices_going_in_to_vertex_with_edge_label(v, g, label=None):
    """
    get_vertices_going_in_to_vertex_with_edge_label
    :param v: the vertex
    :param g: the graph
    :param label: optional parameter - if defined, returns all vertices connected to the given vertex via an edge of the
    defined label. If not defined, returns all vertices going out from the specified vertex
    :return: a list of vertices
    """
    if label is None:
        # inE gets edges going in
        return g.V(v).in_().fold().next()
    else:
        return g.V(v).in_(label).fold().next()


def get_label_counts(g):
    """
    get_label_counts
    :param g: the graph
    :return: a dictionary mapping string labels to integer counts
    """
    return g.V().label().groupCount().next()


def get_edges_with_label(label, g):
    """
    get_edges_with_label
    :param label: a string label
    :return: a list of edges with the label considered
    """
    return g.V().out(label).fold().next()


def get_vertices(g, label=None):
    """
    get_vertices
    :param g: the graph
    :param label: optional parameter; the label type of the vertices considered
    :return: a list of vertices
    """
    if label is None:
        return g.V().fold().next()
    else:
        return g.V(label).fold().next()
	from gremlin_python.structure.graph import Graph
	from gremlin_python.process.graph_traversal import __

	# I use a property instead of directly setting the ID because I could not get it to work, and this works
	# just as well for now. I'd imagine setting the id directly is better for runtime.
	# If you figure out how to set the id directly with gremlin-python, feel free to make a pull request and I'll merge it.
	IDENTIFICATION_PROPERTY = 'identification'
	WEIGHT_PROPERTY = 'weight'

	"""
	Feel free to use this for gremlin-python, which does not have a lot of clear documentation on the differences between
	itself and Groovy, even though there are many.

	This gist offers some abstracted functions to make starting with gremlin-python easy.

	To connect to AWS Neptune with gremlin, you have to use a VPC - you can ssh in your console for example,
	but cannot run a script from PyCharm.

	See how to connect to AWS Neptune from AWS Lambda, which reduces running database operations to basically running a
	PyCharm script, for testing.
	https://docs.aws.amazon.com/neptune/latest/userguide/get-started-cfn-lambda.html
	"""


	def remove_vertex_from_graph(v, g):
	"""
	remove_node_from_graph
	:param v: the vertex to remove
	:param g: the graph
	:return: -
	"""
	g.V(v).drop().iterate()


	def add_vertex_to_graph(ident, label, g):
	"""
	add_node_to_graph
	:param ident: the id for the new vertex
	:param label: the label classifying the vertex
	:param g: the graph
	:return: -
	"""
	return g.addV(label).property(IDENTIFICATION_PROPERTY, str(ident)).next()


	def remove_edge_from_graph(edge, g):
	"""
	remove_node_from_graph
	:param edge: the edge to remove
	:param g: the graph
	:return: -
	"""
	g.E(edge).drop().iterate()


	def add_edge_to_graph(v1, v2, label, g):
	"""
	connect_edges
	:param v1: vertex 1
	:param v2: vertex 2
	:param relation: a string label for the edge
	:param g: the graph
	:return: -
	"""
	return g.V(v1).addE(label).to(g.V(v2)).next()


	def update_edge_weight(edge, increment, g):
	"""
	update_edge_weight
	:param edge: the edge to increment
	:param increment: the amount by which to increment the weight
	:return: -
	"""
	g.E(edge).property(WEIGHT_PROPERTY, increment + get_edge_weight(edge, g).next())


	def get_edge_weight(edge, g):
	"""
	get_edge_weight
	:param edge: the edge, of the type returned by get_edge
	:return: the weight of the given edge
	"""
	values = g.E(edge).valueMap().next()
	return values.get(WEIGHT_PROPERTY, 0)


	def get_edge(v1_id, v2_id, label, g):
	"""
	get_edge
	:param v1_id: the string id of the first vertex
	:param v2_id: the string id of the second vertex
	:param label: string label of the edge, such as 'knows'
	:param g: the graph
	:return: the edge
	"""
	try:
	return g.V(v1_id).outE(label).where(__.inV().where(__.hasId(v2_id))).next()
	except:
	# The edge does not exist.
	return None


	def get_vertex(ident, label, g):
	"""
	get_vertex
	:param ident: string id of the vertex
	:param label: the label of the vertex
	:param g: the graph
	:return: the vertex
	"""
	try:
	return g.V().hasLabel(label).has(IDENTIFICATION_PROPERTY, ident).next()
	except:
	# The vertex does not exist
	return None


	def get_vertices_going_out_from_vertex_with_edge_label(v, g, label=None):
	"""
	get_vertices_going_out_from_vertex_with_edge_label
	:param v: the vertex
	:param g: the graph
	:param label: optional parameter - if defined, returns all vertices connected to the given vertex via an edge of the
	defined label. If not defined, returns all vertices going out from the specified vertex
	:return: a list of vertices
	"""
	if label is None:
	# outE gets edges going out
	return g.V(v).out().fold().next()
	else:
	return g.V(v).out(label).fold().next()


	def get_vertices_going_in_to_vertex_with_edge_label(v, g, label=None):
	"""
	get_vertices_going_in_to_vertex_with_edge_label
	:param v: the vertex
	:param g: the graph
	:param label: optional parameter - if defined, returns all vertices connected to the given vertex via an edge of the
	defined label. If not defined, returns all vertices going out from the specified vertex
	:return: a list of vertices
	"""
	if label is None:
	# inE gets edges going in
	return g.V(v).in_().fold().next()
	else:
	return g.V(v).in_(label).fold().next()


	def get_label_counts(g):
	"""
	get_label_counts
	:param g: the graph
	:return: a dictionary mapping string labels to integer counts
	"""
	return g.V().label().groupCount().next()


	def get_edges_with_label(label, g):
	"""
	get_edges_with_label
	:param label: a string label
	:return: a list of edges with the label considered
	"""
	return g.V().out(label).fold().next()


	def get_vertices(g, label=None):
	"""
	get_vertices
	:param g: the graph
	:param label: optional parameter; the label type of the vertices considered
	:return: a list of vertices
	"""
	if label is None:
	return g.V().fold().next()
	else:
	return g.V(label).fold().next()