Vertex Functions
This page lists the vertex functions that are available in the GSQL query language. The functions are divided into three categories.
Vertex alias methods
Methods available to vertex aliases
Vertex-level access control(VLAC) vertex alias methods
Methods available to vertex aliases that are related to vertex tags.
Vertex functions
Functions that return a vertex or vertex set, or functions that are closely related to certain attributes of
VERTEX
type variables.
Vertex alias methods
This section lists the built-in methods of vertex aliases. Methods can be accessed by the dot (.
) operator.
edgeAttribute()
edgeAttribute()
Syntax
v.edgeAttribute( edgeType, attrName )
Description
From a vertex, traverse edges of a specified type and return the bag of values for a specified edge attribute.
Return type
BagAccum<attrType>
Parameters
filter()
filter()
Syntax
Description
This function is appended to neighbors()
, neighborAttribute()
, or edgeAttribute()
to filter the output set according to a filter condition. Only elements that satisfy the condition will be returned.
Return type
BagAccum
Parameters
Example
getAttr()
getAttr()
Syntax
v.getAttr(attrName, attrType)
Description
Returns the value of a vertex attribute on the vertex.
Return type
attrType
Parameters
neighborAttribute()
neighborAttribute()
Syntax
v.neighborAttribute( edgeType, targetVertexType, attrName )
Description
From a vertex, traverses edges of a specified type to its neighbors of a specified type, and returns the set of values for a specified attribute.
Return type
BagAccum<attrType>
Parameters
Example
For the following graph:
neighbors()
neighbors()
Syntax
v.neighbors([edgeType])
Description
Returns the out-neighbors or undirected neighbors of the vertex. If an edge type is provided, it will only return the neighbors connected by the specified edge type.
Return type
BagAccum<VERTEX>
Parameters
Example
For the following graph:
outdegree()
outdegree()
Syntax
v.outdegree([edgeType])
Description
Returns the number of outgoing or undirected edges connected to the vertex. If an edge type is provided, it will only return the number of edges of the specified type.
Return type
Parameters
Note on outdegree(): This function reads a metadata value stored with each vertex, to avoid traversing the graph and thus have a fast response. The snapshot transaction semantics means that outdegree() may sometimes read an old value if there are concurrent write transactions. To guarantee an accurate count, traverse the neighboring edges and count them with a SumAccum, or use a function like neighbors() and then use size() on the set.
setAttr()
setAttr()
Syntax
v.setAttr( attrName, attrType, newValue )
Description
Sets the specified attribute of a vertex to a new value.
Return type
No return value.
Parameters
VLAC vertex alias methods
This section covers the vertex alias methods used to access and modify tags on vertices,
addTags()
addTags()
Syntax
v.addTags(STRING tag1,... STRING tagN)
Description
Adds the tags provided in the argument list to the vertex.
Return type
No return value.
Parameters
Example:
differenceTags()
differenceTags()
Syntax
v.differenceTags( v2 )
Description
Returns the difference in tags between the vertex and another vertex as a set.
Return type
SET<STRING>
Paramters
Example:
getTags()
getTags()
Syntax
v.getTags()
Descriptions
Returns the vertex's tags as a set. If the vertex has no tags or is untaggable, it returns an empty set.
Return type
SET<STRING>
Parameters
None.
Example:
Tip: getTags()
can be used within a PRINT
statement:
PRINT R [R.getTags()];
or
PRINT R WITH TAGS
which is syntax sugar, except that it won’t print"R.getTags()": []
for non-taggable vertices.
hasTags()
hasTags()
Syntax
hasTags( tag1, tag2, ..., tagN )
Description
Returns true
if the vertex has every tag provided in the argument list and returns false
if it does not.
Return type
BOOL
Parameters
Example:
The output of the query would be:
isTaggable()
isTaggable()
Syntax
v.isTaggable()
Description
Returns true if the vertex is taggable.
Return type
BOOL
Parameters
None
Example:
intersectTags()
intersectTags()
Syntax
v.intersectTags( v2 )
Description
Returns the common tags between the vertex and another vertex as a set.
Return type
SET<STRING>
Example:
removeAllTags()
removeAllTags()
Syntax
v.removeAllTags()
Description
Removes all tags from the vertex.
Return type
No return value.
Parameters
None
Example:
removeTags()
removeTags()
Syntax
removeTags( tag1, tag2, ..., tagN )
Description
Removes the tags provided in the argument list from the vertex.
Return type
No return value.
Parameters
Example
Vertex functions
The functions in this section either have return values of vertex or vertex set type or are closely related to vertex attributes.
getvid()
getvid()
Syntax
getvid( id )
Description
Returns the internal ID number of a vertex.
The internal ID is not the primary ID which the user assigned when creating the vertex. However, there is a 1-to-1 mapping between the external ID (primary_id
) and internal ID.
The engine can access the internal ID faster than accessing the external ID, so if a query needs unique values for a large number of vertices, but doesn't care about particular values, getvid()
can be a useful option. For example, in many community detection algorithms, we start by assigning every vertex a unique community ID. Then, as the algorithm progresses, some vertices will join the community of one of their neighbors, giving up their current community ID and copying the IDs of their neighbors.
Return type
STRING
Parameters
selectVertex()
selectVertex()
Syntax
selectVertex( filepath, vertexIdColumn, vertexTypeColumn, seperator, header)
Description
Reads a data file that lists particular vertices of the graph and returns the corresponding vertex set. This function can only be used in a vertex set variable declaration statement as a seed set and the vertices in the data file must already be in the graph. The data file must be organized as a table with one or more columns. One column must be for vertex ID. Optionally, another column is for vertex type.
Return type
SET<VERTEX>
Parameters
Example
to_vertex()
to_vertex()
Running to_vertex() and to_vertex_set()
requires real-time conversion of an external ID to a GSQL internal ID, which is a relatively slow process. Therefore,
If the user can always know the id before running the query, define the query with
VERTEX
orSET<VERTEX>
parameters instead ofSTRING
orSET<STRING>
parameters, and avoid callingto_vertex()
orto_vertex_set()
.Calling
to_vertex_set()
one time is much faster than callingto_vertex()
multiple times. Useto_vertex_set()
instead ofto_vertex()
as much as possible.
Syntax
to_vertex( id, vertex_type )
Description
Returns a vertex from a string ID and vertex type. If a vertex with the provided ID and type does not exist, the function will throw a run-time error.
Return type
VERTEX
Parameters
Example
to_vertex_set()
to_vertex_set()
Syntax
to_vertex_set( id_set, vertex_type)
Description
Returns a vertex set from a set or bag of string IDs and a vertex type. If there are invalid IDs in the set, those IDs will be skipped and the response will contain a warning message. If the vertex type does not exist, the function will throw a run-time error.
Return type
SET<VERTEX>
Parameters
Example
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