Vertex Objects

pyvgx.Vertex

class pyvgx.Vertex( graph, id[, type_[, mode[, timeout ]]] )

The pyvgx.Vertex type represents the Python layer’s view of VGX vertex objects. Objects of this class are wrappers that enable Python code to access core VGX vertices.

Parameters

Parameter Type Default Description

Parameter	Type	Default	Description
graph	`pyvgx.Graph` instance		Parent graph
id	str or bytes or int		Unique vertex identifier string or memory address known to reference vertex
type	str or bytes	`None`
mode	chr	"a"	Access mode: "w" (writable), "a" (modify), or "r" (readonly)
timeout	int	0	Milliseconds to block while waiting for access

graph

pyvgx.Graph instance

Parent graph

str or bytes or int

Unique vertex identifier string or memory address known to reference vertex

type

str or bytes

None

mode

chr

"a"

Access mode: "w" (writable), "a" (modify), or "r" (readonly)

timeout

int

Milliseconds to block while waiting for access

Remarks

The pyvgx.Vertex type represents VGX core vertex objects. The returned Python object is a wrapper around the internal VGX vertex object.

This constructor creates a new VGX vertex in parent graph or opens an existing VGX vertex. If the vertex already exists id may be given as a string or as a memory address known to reference the vertex. If the vertex does not already exist id must be a string.

The optional type string may only be specified if the mode is "w", otherwise ValueError is raised. If the vertex already exists with a type other than type ValueError is raised. When type is None (the default) a typeless vertex is created.

The optional mode character specifies access type.

Mode Description

Mode	Description
`"w"`	Open vertex writable and create if it does not exist
`"a"`	Open vertex writable but do not create
`"r"`	Open vertex readonly

"w"

Open vertex writable and create if it does not exist

"a"

Open vertex writable but do not create

"r"

Open vertex readonly

Both "a" and "r" will raise KeyError if vertex does not exist.

An optional timeout in milliseconds may be specified to allow blocking while waiting for vertex to become available to the calling thread.

Instead of calling this constructor directly it is recommended to use one of the following pyvgx.Graph API methods:

Example

import pyvgx
pyvgx.system.Initialize()
g = pyvgx.Graph( "graph1" )
A = pyvgx.Vertex( g, "A", "node", "w" ) # create "A" of type "node"
del A
A = pyvgx.Vertex( g, "A", mode="r" )    # open "A" readonly

pyvgx.Vertex API

pyvgx.Vertex API Section	Description
Vertex Members	Vertex object members
Vertex Access Methods	Methods for checking and modifying vertex access mode
Vertex Property Methods	Methods for managing vertex properties
Vertex Rank Methods	Methods for accessing vertex ranking coefficients
Vertex Vector Methods	Methods for managing vertex vectors
Vertex TTL Methods	Methods for managing vertex expiration
Vertex Miscellaneous Methods	Methods for accessing and managing various vertex attributes
Vertex Condition Syntax	Syntax rules for vertex conditions used in queries General Syntax Constraints Evaluation Order Vertex Filters

pyvgx.Vertex API Section

Description

Vertex Members

Vertex object members

Vertex Access Methods

Methods for checking and modifying vertex access mode

Vertex Property Methods

Methods for managing vertex properties

Vertex Rank Methods

Methods for accessing vertex ranking coefficients

Vertex Vector Methods

Methods for managing vertex vectors