Filter expressions are expressions that are evaluated for each vertex or edge. The expression can define predicates that a vertex or an edge must fulfil in order to be contained in the result, in this case a subgraph.

Consider an example graph that consists of four vertices (nodes) and four edges. For an edge to match the filter expression src.prop == 10, the source vertex prop property must equal 10. Two edges match that filter expression, as shown in the following figure.

The following figure shows the graph that results when the filter is applied.

The vertex filter src.prop == 10 filters out the edges associated with vertex 333 and the vertex itself.