Geo-Layout for Dynamic Network in Nodegoat
Yanan Sun
[email protected]
1. Terminology Difference
In Nodegoat, you can understand the terminology in this way: "Type" is mode in the
language of SNA; "Object" is node or vertex in SNA. There are two preset types in
Nodegoat -"City" and "Country"-to facilitate the input of geo-information, so that you
don't have to type in the latitude and longitude manually.
2. Example Scenario
Suppose we want to visualize the trade dynamics between 4 cities- Berlin, Amsterdam,
Paris, and London- from 2008 to 2014. In SNA, we normally have 4 nodes representing
the 4 cities, and the transaction records, which are the links we want visualize on the map
over time.
Table of Transaction Records
City
City
Transaction Records
Paris
Berlin
12 Dec, 2008
Amsterdam
Berlin
12 May,2009
Berlin
London
12 Dec,2009
London
Paris
05 May,2011
Amsterdam
Paris
03 Sept.2011
Berlin
London
05 Aug,2013
Paris
Amsterdam
01 Jun,2014
3. Design Data Structure
Node
In this example, we decide one mode of nodes should be sufficient. Therefore, we set up
one type in Nodegoat. Go to Design>Add Type
Under the tag of "Type," give the name of the mode and other information about this
mode.
Go to the tag of "Object." Remember, here is how you define your nodes, e.g., ID in
your original dataset. When the "Name Field" stays clicked, Nodegoat will recognize the
information in this field as identifier.
Note, here is NOT the place to store geo- or temporal information for the nodes, because
information here cannot be used to define connections with other nodes. To make a node
appear on the map, you have to set up a Subobject (let us name the subobject in our
example with "City Info") to give geo and temporal information about the nodes. You
have to give BOTH sorts of information, i.e., the time of appearance AND the location of
the nodes; otherwise, it will not appear in the final visualization1. If you do not have
information about when a node first appears, just give a time earlier than any links
appearance or the time when it for the first time has relation with another nodes. The first
approach is practical for networks with isolates; the second is good for networks without
isolates. For the location, we can simply choose default type "City" in Nodegoat.
1
This is because, Nodegoat follows the real-world logic; If a node has only a location and we do not know
when it appears, it is supposed it has never appeared. Vice versa is also true. If we know a node appears at a
certain time, but have no information where it appears, we have also no idea to where we should pin this
node down.
Click "Save Type," the type of "Trade Cites" is listed under Types. Click on the button of
"edit" to continue set up links.
Links
Links are defined under Subobject as well. Got to the tag of "Subobject" again and let
us add a new Subobject called "Transactions." Remember all links also must have
temporal information, otherwise they will not be shown on the map. This is actually the
core and value of dynamic network analysis. Different from the Subobject of "City
Info," the location information of this Subobject must point to the location of another
node (i.e., object) in order to tell Nodegoat there is a link between the two nodes.
Therefore, in the drop-down menus of "Location Reference," we should choose "Trade
Cities" and "City Info." Save the Type again.
4. Set up a new project
Because Nodegoat allows users to share nodes for different visualizations, it is better to
set up a new project for each work.
Go to Management>Projects>Add Project
Give a name to the project and choose the Types we need for the project, then save.
5. Data Input
Nodes Input
Now, we can put in our data. Got to Data and click on None to select our project
"Trade."
Click on the Type of "Trade Cities" we can start type in data. Fill in the information for object
then click on the first Subobject of "City Info" to give the geo-and temporal information for the
node of "Berlin."
We choose the first method of dealing with temporal information, so we give in the earliest time
of the transaction records. Type in "Berlin" in the location Reference, Nodegoat will pin your
node to the map automatically. Use the same method to add another three nodes.
Links Input
Then click on the Subobject of "Transactions" of a node to give link information
according to the Table of Transaction Records.
After transcribing all link information into Nodegoat, click on the global button on the
top-right corner. If all data are correctly filled in, you should be able to see the geolayout
for the dynamic network. Slide the time bar to focus on different periods of interest. Have
fun playing with the goat!