Networks Extension Dictionary: save-graphml

nw:save-graphml

nw:save-graphml file-name

You can save the current graph to GraphML. The following NetLogo code:

extensions [ nw ]

breed [ bankers banker ]
bankers-own [ bank-name ]
breed [ clients client ]
clients-own [ hometown ]

undirected-link-breed [ friendships friendship ]

directed-link-breed [ accounts account ]
accounts-own [ amount ]

to go
  clear-all
  create-bankers 1 [
    set bank-name "The Bank"
  ]
  create-clients 1 [
    set hometown "Turtle City"
    create-friendship-with banker 0
    create-account-to banker 0 [
      set amount 9999.99
    ]
  ]
  nw:set-context turtles links
  nw:save-graphml "example.graphml"
end

Will produce the following GraphML file:

<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns/graphml"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns/graphml">
<key id="PEN-MODE" for="node" attr.name="PEN-MODE" attr.type="string"/>
<key id="YCOR" for="node" attr.name="YCOR" attr.type="double"/>
<key id="PEN-SIZE" for="node" attr.name="PEN-SIZE" attr.type="double"/>
<key id="LABEL" for="node" attr.name="LABEL" attr.type="string"/>
<key id="SHAPE" for="node" attr.name="SHAPE" attr.type="string"/>
<key id="BREED" for="node" attr.name="BREED" attr.type="string"/>
<key id="WHO" for="node" attr.name="WHO" attr.type="double"/>
<key id="HIDDEN?" for="node" attr.name="HIDDEN?" attr.type="boolean"/>
<key id="LABEL-COLOR" for="node" attr.name="LABEL-COLOR" attr.type="double"/>
<key id="HEADING" for="node" attr.name="HEADING" attr.type="double"/>
<key id="BANK-NAME" for="node" attr.name="BANK-NAME" attr.type="string"/>
<key id="HOMETOWN" for="node" attr.name="HOMETOWN" attr.type="string"/>
<key id="COLOR" for="node" attr.name="COLOR" attr.type="double"/>
<key id="XCOR" for="node" attr.name="XCOR" attr.type="double"/>
<key id="SIZE" for="node" attr.name="SIZE" attr.type="double"/>
<key id="END1" for="edge" attr.name="END1" attr.type="string"/>
<key id="TIE-MODE" for="edge" attr.name="TIE-MODE" attr.type="string"/>
<key id="END2" for="edge" attr.name="END2" attr.type="string"/>
<key id="LABEL-COLOR" for="edge" attr.name="LABEL-COLOR" attr.type="double"/>
<key id="THICKNESS" for="edge" attr.name="THICKNESS" attr.type="double"/>
<key id="LABEL" for="edge" attr.name="LABEL" attr.type="string"/>
<key id="SHAPE" for="edge" attr.name="SHAPE" attr.type="string"/>
<key id="BREED" for="edge" attr.name="BREED" attr.type="string"/>
<key id="COLOR" for="edge" attr.name="COLOR" attr.type="double"/>
<key id="AMOUNT" for="edge" attr.name="AMOUNT" attr.type="double"/>
<key id="HIDDEN?" for="edge" attr.name="HIDDEN?" attr.type="boolean"/>
<graph edgedefault="undirected">
<node id="client 1">
<data key="PEN-MODE">up</data>
<data key="YCOR">0</data>
<data key="PEN-SIZE">1</data>
<data key="LABEL"></data>
<data key="SHAPE">default</data>
<data key="BREED">clients</data>
<data key="WHO">1</data>
<data key="HIDDEN?">false</data>
<data key="LABEL-COLOR">9.9</data>
<data key="HEADING">356</data>
<data key="HOMETOWN">Turtle City</data>
<data key="COLOR">115</data>
<data key="XCOR">0</data>
<data key="SIZE">1</data>
</node>
<node id="banker 0">
<data key="PEN-MODE">up</data>
<data key="YCOR">0</data>
<data key="PEN-SIZE">1</data>
<data key="LABEL"></data>
<data key="SHAPE">default</data>
<data key="BREED">bankers</data>
<data key="WHO">0</data>
<data key="HIDDEN?">false</data>
<data key="LABEL-COLOR">9.9</data>
<data key="HEADING">32</data>
<data key="BANK-NAME">The Bank</data>
<data key="COLOR">85</data>
<data key="XCOR">0</data>
<data key="SIZE">1</data>
</node>
<edge source="client 1" target="banker 0">
<data key="END1">(client 1)</data>
<data key="TIE-MODE">none</data>
<data key="END2">(banker 0)</data>
<data key="LABEL-COLOR">9.9</data>
<data key="THICKNESS">0</data>
<data key="LABEL"></data>
<data key="SHAPE">default</data>
<data key="BREED">accounts</data>
<data key="COLOR">5</data>
<data key="AMOUNT">9999.99</data>
<data key="HIDDEN?">false</data>
</edge>
<edge source="banker 0" target="client 1">
<data key="END1">(banker 0)</data>
<data key="TIE-MODE">none</data>
<data key="END2">(client 1)</data>
<data key="LABEL-COLOR">9.9</data>
<data key="THICKNESS">0</data>
<data key="LABEL"></data>
<data key="SHAPE">default</data>
<data key="BREED">friendships</data>
<data key="COLOR">5</data>
<data key="HIDDEN?">false</data>
</edge>
</graph>
</graphml>

A few things to notice:

The breed is stored as data field, both for nodes and edges. Note that the breed is stored in its plural form.
The data includes both NetLogo’s internal variables and the variables that were defined as either breeds-own, turtles-own, linkbreeds-own or links-own.
Each key gets an attr.type based on the actual types of the values contained in the agent variables. The three possible types are "string", "double" and "boolean". To determine the attribute type of a particular agent variable, the extension will look at the first agent in the graph. To see which agent is first, you can look at the result of nw:get-context. Note that variables containing other types of values, such as turtles, patches, lists, etc., will be stored as strings.
This example only has a directed link, and you will notice the <graph edgedefault="directed"> element. If we had only undirected links, we would have <graph edgedefault="undirected">. What if we try to mix both kinds of link? At the moment, the extension will save such a “mixed” graph as if it were an undirected graph (see this issue for more details). The order of the source and target will be respected, however, so if you know which breeds represent directed links, you can figure it out a posteriori.