Graphics Reference
In-Depth Information
Finally, notice that, because you gathered nodes linked in both directions,
there is a duplicate reference to the
Drawing Graphs
book, indicating that
each book is listed as being similar to the other. If the title is any indication,
they are also the most similar in subject. You can use the
dedup()
step to
eliminate duplicates, as shown here:
gremlin>
g.V('group','Book').has('title',CONTAINS,'Graph').has('title',
CONTAINS,'Visualization').both('similar').dedup().title
Alternatively, you can use the
groupCount()
step to count instances of
each. Processing the results of grouping requires more advanced Gremlin
and shows how Gremlin tends to become more complex when the output of
a step is not easily expressed as a simple list of single elements. To output a
list of counts by book, the
cap
statement used in the following code moves
back one step in the pipeline output (which is otherwise a list of counts) to
the map produced as a side effect. The
scatter()
step then unrolls the
map into a list of key/value entries, and
transform
is used to output each
entry with its title.
gremlin>
g.V('group','Book').has('title',CONTAINS,'Graph').has('title',
CONTAINS,'Visualization').both('similar').groupCount().
cap.scatter().transform(){[it.value,
it.key.title]}
==>[1, Computational Modeling of Genetic and
Biochemical Networks
(Computational Molecular Biology)]
==>[2, Drawing Graphs : Methods and Models (Lecture
Notes in
Computer Science)]
==>[1, Introduction to Graph Theory (Dover topics on
Advanced
Mathematics)]
==>[1, Computational Analysis of Biochemical Systems :
A Practical
Guide for Biochemists and Molecular Biologists]
