5.7 Using the SOURCE and DESTINATION Predicates

You can determine if a vertex is a source or destination using the IS [NOT] SOURCE OF or IS [NOT] DESTINATION OF predicate in a value expression inside a WHERE or COLUMNS clause.

These predicates are mainly useful for determining the direction of edges that are matched through any-directed edge patterns (<-[]-> or -[]-).

The IS [NOT] SOURCE OF predicate takes a vertex and an edge as input and returns TRUE or FALSE depending on whether the vertex is (or not) the source of the edge.

The IS [NOT] DESTINATION OF predicate also takes a vertex and an edge as input and returns TRUE or FALSE depending on whether the vertex is (or not) the destination of the edge.

See Example 5-24 for more information.