!CHAPTER Graph Functions

This chapter describes various functions on a graph.

!SECTION Get vertices from edges.

!SUBSECTION Get vertex *from* of an edge

Get the vertex of an edge defined as *_from*
<br />
`general-graph._getFromVertex(edgeId)`
<br />
Returns the vertex defined with the attribute *_from* of the edge with *edgeId* as its *_id*.
<br />
@EXAMPLES
<br />

```
arangosh>   var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh>   var g = examples.loadGraph("social");
arangosh>   g._getFromVertex("relation/aliceAndBob")
{ 
  "name" : "Alice", 
  "_id" : "female/alice", 
  "_rev" : "236262839", 
  "_key" : "alice" 
}
```
<br />

!SUBSECTION Get vertex *to* of an edge

Get the vertex of an edge defined as *_to*
<br />
`general-graph._getToVertex(edgeId)`
<br />
Returns the vertex defined with the attribute *_to* of the edge with *edgeId* as its *_id*.
<br />
@EXAMPLES
<br />

```
arangosh>   var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh>   var g = examples.loadGraph("social");
arangosh>   g._getToVertex("relation/aliceAndBob")
{ 
  "name" : "Bob", 
  "_id" : "male/bob", 
  "_rev" : "70784439", 
  "_key" : "bob" 
}
```
<br />


!SECTION _listCommonNeighbors

<br />
`general_graph._listCommonNeighbors(vertex1Example, vertex2Examples,
optionsVertex1, optionsVertex2)`
*The general_graph._listCommonNeighbors function returns all common neighbors
of the vertices defined by the examples.*
<br />
The function accepts an id, an example, a list of examples or even an empty
example as parameter for vertex1Example and vertex2Example.
<br />
* String|Object|Array  *vertex1Example*     : An example for the desired
vertices (see below).
* String|Object|Array  *vertex2Example*     : An example for the desired
vertices (see below).
* Object               *optionsVertex1*     : Optional options, see below:
* Object               *optionsVertex2*     : Optional options, see below:
<br />
Possible options and there defaults:
* String               *direction*                        : The direction of the
edges. Possible values are *outbound*, *inbound* and *any* (default).
* String|Object|Array  *edgeExamples*                     : A filter example
for the edges to the neighbors (see below).
* String|Object|Array  *neighborExamples*                 : An example for
the desired neighbors (see below).
* String|Array         *edgeCollectionRestriction*        : One or multiple
edge collections that should be considered.
// * String|Array         *vertexCollectionRestriction* : One or multiple
vertex collections that should be considered.
// / * Number               *minDepth*                         : Defines the minimal
depth a path to a neighbor must have to be returned (default is 1).
* Number               *maxDepth*                         : Defines the maximal
depth a path to a neighbor must have to be returned (default is 1).
<br />
Examples for vertexExample:
* {}                : Returns all possible vertices for this graph.
* *idString*        : Returns the vertex with the id *idString*.
* {*key* : *value*} : Returns the vertices that match this example.
* [{*key1* : *value1*}, {*key2* : *value2*}] : Returns the vertices that
match one of the examples.
<br />
@EXAMPLES
<br />
A route planner example, all common neighbors of capitals.
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._listCommonNeighbors({isCapital : true}, {isCapital : true});
[ 
  { 
    "city/Berlin" : { 
      "city/Munich" : [ 
        { 
          "_id" : "city/Cologne", 
          "_rev" : "339311159", 
          "_key" : "Cologne", 
          "isCapital" : false, 
          "population" : 1000000 
        }, 
        { 
          "_id" : "village/Olpe", 
          "_rev" : "339966519", 
          "_key" : "Olpe", 
          "isCapital" : false, 
          "population" : 80000 
        }, 
        { 
          "_id" : "village/Rosenheim", 
          "_rev" : "340163127", 
          "_key" : "Rosenheim", 
          "isCapital" : false, 
          "population" : 80000 
        } 
      ] 
    } 
  }, 
  { 
    "city/Munich" : { 
      "city/Berlin" : [ 
        { 
          "_id" : "city/Cologne", 
          "_rev" : "339311159", 
          "_key" : "Cologne", 
          "isCapital" : false, 
          "population" : 1000000 
        }, 
        { 
          "_id" : "village/Olpe", 
          "_rev" : "339966519", 
          "_key" : "Olpe", 
          "isCapital" : false, 
          "population" : 80000 
        }, 
        { 
          "_id" : "village/Rosenheim", 
          "_rev" : "340163127", 
          "_key" : "Rosenheim", 
          "isCapital" : false, 
          "population" : 80000 
        } 
      ] 
    } 
  } 
]
```
<br />
A route planner example, all common outbound neighbors of munich with any other location
which have a maximal depth of 2 :
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._listCommonNeighbors('city/Munich', {}, {direction : 'outbound', maxDepth : 2},
........> {direction : 'outbound', maxDepth : 2});
[ 
  { 
    "city/Munich" : { 
      "city/Berlin" : [ 
        { 
          "_id" : "city/Cologne", 
          "_rev" : "424901175", 
          "_key" : "Cologne", 
          "isCapital" : false, 
          "population" : 1000000 
        }, 
        { 
          "_id" : "village/Olpe", 
          "_rev" : "425556535", 
          "_key" : "Olpe", 
          "isCapital" : false, 
          "population" : 80000 
        }, 
        { 
          "_id" : "village/Rosenheim", 
          "_rev" : "425753143", 
          "_key" : "Rosenheim", 
          "isCapital" : false, 
          "population" : 80000 
        } 
      ], 
      "city/Cologne" : [ 
        { 
          "_id" : "village/Olpe", 
          "_rev" : "425556535", 
          "_key" : "Olpe", 
          "isCapital" : false, 
          "population" : 80000 
        }, 
        { 
          "_id" : "village/Rosenheim", 
          "_rev" : "425753143", 
          "_key" : "Rosenheim", 
          "isCapital" : false, 
          "population" : 80000 
        } 
      ] 
    } 
  } 
]
```
<br />



!SECTION _amountCommonNeighbors

<br />
`general_graph._amountCommonNeighbors(vertex1Example, vertex2Examples,
optionsVertex1, optionsVertex2)`
*The general_graph._amountCommonNeighbors function returns the amount of
common neighbors of the vertices defined by the examples.*
<br />
The function accepts an id, an example, a list of examples or even an empty
example as parameter for vertex1Example and vertex2Example.
<br />
* String|Object|Array  *vertex1Example*     : An example for the desired
vertices (see below).
* String|Object|Array  *vertex2Example*     : An example for the desired
vertices (see below).
* Object               *optionsVertex1*     : Optional options, see below:
* Object               *optionsVertex2*     : Optional options, see below:
<br />
Possible options and there defaults:
* String               *direction*                        : The direction of the
edges. Possible values are *outbound*, *inbound* and *any* (default).
* String|Object|Array  *edgeExamples*                     : A filter example
for the edges to the neighbors (see below).
* String|Object|Array  *neighborExamples*                 : An example for
the desired neighbors (see below).
* String|Array         *edgeCollectionRestriction*        : One or multiple
edge collections that should be considered.
// * String|Array         *vertexCollectionRestriction* : One or multiple
vertex collections that should be considered.
// / * Number               *minDepth*                         : Defines the minimal
depth a path to a neighbor must have to be returned (default is 1).
* Number               *maxDepth*                         : Defines the maximal
depth a path to a neighbor must have to be returned (default is 1).
<br />
Examples for vertexExample:
* {}                : Returns all possible vertices for this graph.
* *idString*        : Returns the vertex with the id *idString*.
* {*key* : *value*} : Returns the vertices that match this example.
* [{*key1* : *value1*}, {*key2* : *value2*}] : Returns the vertices that
match one of the examples.
<br />
@EXAMPLES
<br />
A route planner example, all common neighbors of capitals.
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._amountCommonNeighbors({isCapital : true}, {isCapital : true});
[ 
  { 
    "city/Berlin" : [ 
      { 
        "city/Munich" : 3 
      } 
    ] 
  }, 
  { 
    "city/Munich" : [ 
      { 
        "city/Berlin" : 3 
      } 
    ] 
  } 
]
```
<br />
A route planner example, all common outbound neighbors of munich with any other location
which have a maximal depth of 2 :
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._amountCommonNeighbors('city/Munich', {}, {direction : 'outbound', maxDepth : 2},
........> {direction : 'outbound', maxDepth : 2});
[ 
  { 
    "city/Munich" : [ 
      { 
        "city/Berlin" : 3 
      }, 
      { 
        "city/Cologne" : 2 
      } 
    ] 
  } 
]
```
<br />



!SECTION _listCommonProperties

<br />
`general_graph._listCommonProperties(vertex1Example, vertex2Examples,
options)`
*The general_graph._listCommonProperties function returns the vertices of
the graph that share common properties.*
<br />
The function accepts an id, an example, a list of examples or even an empty
example as parameter for vertex1Example and vertex2Example.
<br />
* String|Object|Array  *vertex1Example*     : An example for the desired
vertices (see below).
* String|Object|Array  *vertex2Example*     : An example for the desired
vertices (see below).
* Object               *options*     : Optional options, see below:
<br />
Possible options and there defaults:
// * String|Array         *vertex1CollectionRestriction* : One or multiple
vertex collections that should be considered.
* String|Array         *vertex2CollectionRestriction* : One or multiple
vertex collections that should be considered.
* String|Array         *ignoreProperties* : One or multiple
attributes of a document that should be ignored.
<br />
Examples for vertexExample:
* {}                : Returns all possible vertices for this graph.
* *idString*        : Returns the vertex with the id *idString*.
* {*key* : *value*} : Returns the vertices that match this example.
* [{*key1* : *value1*}, {*key2* : *value2*}] : Returns the vertices that
match one of the examples.
<br />
@EXAMPLES
<br />
A route planner example, all locations with the same properties:
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._listCommonProperties({}, {});
[ 
  { 
    "city/Berlin" : [ 
      { 
        "_id" : "city/Munich", 
        "_rev" : "174396855", 
        "_key" : "Munich", 
        "isCapital" : true, 
        "population" : 1000000 
      } 
    ] 
  }, 
  { 
    "city/Cologne" : [ 
      { 
        "_id" : "village/Rosenheim", 
        "_rev" : "175052215", 
        "_key" : "Rosenheim", 
        "isCapital" : false, 
        "population" : 80000 
      }, 
      { 
        "_id" : "village/Olpe", 
        "_rev" : "174855607", 
        "_key" : "Olpe", 
        "isCapital" : false, 
        "population" : 80000 
      }, 
      { 
        "_id" : "city/Munich", 
        "_rev" : "174396855", 
        "_key" : "Munich", 
        "isCapital" : true, 
        "population" : 1000000 
      } 
    ] 
  }, 
  { 
    "city/Munich" : [ 
      { 
        "_id" : "city/Berlin", 
        "_rev" : "174003639", 
        "_key" : "Berlin", 
        "isCapital" : true, 
        "population" : 3000000 
      }, 
      { 
        "_id" : "city/Cologne", 
        "_rev" : "174200247", 
        "_key" : "Cologne", 
        "isCapital" : false, 
        "population" : 1000000 
      } 
    ] 
  }, 
  { 
    "village/Olpe" : [ 
      { 
        "_id" : "city/Cologne", 
        "_rev" : "174200247", 
        "_key" : "Cologne", 
        "isCapital" : false, 
        "population" : 1000000 
      }, 
      { 
        "_id" : "village/Rosenheim", 
        "_rev" : "175052215", 
        "_key" : "Rosenheim", 
        "isCapital" : false, 
        "population" : 80000 
      } 
    ] 
  }, 
  { 
    "village/Rosenheim" : [ 
      { 
        "_id" : "city/Cologne", 
        "_rev" : "174200247", 
        "_key" : "Cologne", 
        "isCapital" : false, 
        "population" : 1000000 
      }, 
      { 
        "_id" : "village/Olpe", 
        "_rev" : "174855607", 
        "_key" : "Olpe", 
        "isCapital" : false, 
        "population" : 80000 
      } 
    ] 
  } 
]
```
<br />
A route planner example, all cities which share same properties except for population.
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._listCommonProperties({}, {}, {vertex1CollectionRestriction : 'city',
........>  vertex2CollectionRestriction : 'city' ,ignoreProperties: 'population'});
[ 
  { 
    "city/Berlin" : [ 
      { 
        "_id" : "city/Munich", 
        "_rev" : "179574199", 
        "_key" : "Munich", 
        "isCapital" : true, 
        "population" : 1000000 
      } 
    ] 
  }, 
  { 
    "city/Munich" : [ 
      { 
        "_id" : "city/Berlin", 
        "_rev" : "179180983", 
        "_key" : "Berlin", 
        "isCapital" : true, 
        "population" : 3000000 
      } 
    ] 
  } 
]
```
<br />



!SECTION _amountCommonProperties

<br />
`general_graph._amountCommonProperties(vertex1Example, vertex2Examples,
options)`
*The general_graph._amountCommonProperties function returns the amount of vertices of
the graph that share common properties.*
<br />
The function accepts an id, an example, a list of examples or even an empty
example as parameter for vertex1Example and vertex2Example.
<br />
* String|Object|Array  *vertex1Example*     : An example for the desired
vertices (see below).
* String|Object|Array  *vertex2Example*     : An example for the desired
vertices (see below).
* Object               *options*     : Optional options, see below:
<br />
Possible options and there defaults:
// * String|Array         *vertex1CollectionRestriction* : One or multiple
vertex collections that should be considered.
* String|Array         *vertex2CollectionRestriction* : One or multiple
vertex collections that should be considered.
* String|Array         *ignoreProperties* : One or multiple
attributes of a document that should be ignored.
<br />
Examples for vertexExample:
* {}                : Returns all possible vertices for this graph.
* *idString*        : Returns the vertex with the id *idString*.
* {*key* : *value*} : Returns the vertices that match this example.
* [{*key1* : *value1*}, {*key2* : *value2*}] : Returns the vertices that
match one of the examples.
<br />
@EXAMPLES
<br />
A route planner example, all locations with the same properties:
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._amountCommonProperties({}, {});
[ 
  { 
    "city/Berlin" : 1 
  }, 
  { 
    "city/Cologne" : 3 
  }, 
  { 
    "city/Munich" : 2 
  }, 
  { 
    "village/Olpe" : 2 
  }, 
  { 
    "village/Rosenheim" : 2 
  } 
]
```
<br />
A route planner example, all cities which share same properties except for population.
<br />

```
arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var g = examples.loadGraph("routeplanner");
arangosh> g._amountCommonProperties({}, {}, {vertex1CollectionRestriction : 'city',
........>  vertex2CollectionRestriction : 'city' ,ignoreProperties: 'population'});
[ 
  { 
    "city/Berlin" : 1 
  }, 
  { 
    "city/Munich" : 1 
  } 
]
```
<br />