Contents

• gremlinx
  • Getting start
    • Basic Gremlimx queries
    • Retrieving property values from a vertex
    • Does a specific property exist on a given vertex or edge?
    • Counting things
    • Counting groups of things

gremlinx

GremlinX is an attempt to implement the gremlin language on networkx.

Getting start

Load a dataset of air routes Load a dataset of air routes

from gremlinx.core import (
    GraphTraversalSource,
)
import networkx as nx

G = nx.read_graphml("test/data/air-routes.graphml")
g = GraphTraversalSource(graph=G)

Basic Gremlimx queries

The query below will return any vertices (nodes) that have the airport label.

# Find vertices that are airports
g.V().hasLabel('airport')

This query will return the vertex that represents the Dallas Fort Worth (DFW) airport.

# Find the DFW vertex
g.V().has('code','DFW')

The next two queries combine the previous two into a single query.

# Combining those two previous queries (two ways that are equivalent)
g.V().hasLabel('airport').has('code','DFW')

g.V().has('airport','code','DFW')

Retrieving property values from a vertex

# What property values are stored in the DFW vertex?
g.V().has('airport','code','DFW').values()

The values step can take parameters that tell it to only return the values for the provided key names.

g.V().has('airport','code','DFW').values('city')

g.V().has('airport','code','DFW').values('runways','icao')

Does a specific property exist on a given vertex or edge?

You can simply test to see if a property exists as well as testing for it containing a specific value.

# Find all edges that have a 'dist' property
g.E().has('dist')

# Find all vertices that have a 'region' property
g.V().has('region')

# Find all the vertices that do not have a 'region' property
g.V().hasNot('region')

# The above is shorthand for
 g.V().not(has('region'))

Counting things

# How many airports are there in the graph?
g.V().hasLabel('airport').count()

# How many routes are there?
g.V().hasLabel('airport').outE('route').count()

# How many routes are there?
g.V().outE('route').count()

# How many routes are there?
g.E().hasLabel('route').count()

Counting groups of things

# How many of each type of vertex are there?
g.V().groupCount().by(label)

We can also run a similar query to find out the distribution of edge labels in the graph

# How many of each type of edge are there?
g.E().groupCount().by(label)

By way of a side note, the examples above are shorthand ways of writing something like this example which also counts vertices by label.

# As above but using group()
g.V().group().by(label).by(count())

# How many airports are there in each country?
g.V().hasLabel('airport').groupCount().by('country')