My problem is that I want to make an animation of the world dyadic trade network as it evolved from 1790 to 1919. Not knowing how to do time dynamics with csv files made using Excel, I am taking a screenshot of each year of data and putting it into an animated gif file.
I found that careful (dare I say fanatical) adherence to a particular structure for the nodes and edges files and a particular sequence of steps in Gephi seems to work. This is what I do.
1. Create a New Project.
2. Go to Data Laboratory and select Import Spreadsheet.
3. Select Nodes table and then use the file browser to select the desired nodes file.
My nodes file has the following structure in terms of columns and column labels:
Id Label lat lng
Id is a number identifying (in my case) a country, Label is text of the country name, and lat and lng are the latitude and longitude in decimal format (e.g. 32.34, -95.14) (of in my case the geographic center of the country). My file has several rows in this format.
4. In the Import settings window, make sure lat and lng are set to be data type Double. Finish.
5. Select Import Spreadsheet again, select Edges table, and then select the desired edges file.
6. My edges files (one for each year) have the following structure:
Source Target Type Weight Year Source Name Target Name
The first four columns and column labels are essential, the last three are for human comprehension of what the data are about.
Source and Target are the appropriate numbers in the Id column of the nodes file, Type is (in my case) the text string directed, Weight is a numerical value attached to the edge (in my case the US $ value of the directed trade flow). Each edges file has a number of rows in this format.
My Import settings do not need to be changed. Finish.
7. Select Overview and select ---Choose a layout.
8. Select Map of Countries and select the desired Projection. Click on Run.
9. Select Geo layout under Layout, select lng for Longitude, and make sure the Projection matches the projection chosen for Map of Countries. Click on Run.
I get my nodes properly geo-located and the correct edges connecting the nodes. I adjust the map by using my scroll wheel to change the map size and pressing the right mouse button and panning to move the map around. I adjust the edge thickness slider to make the boundaries more visible. I then take a screenshot of the map and network overlay using my Mac's screenshot command (shift-command-4) as it gives a better image than the built-in Gephi screenshot command.
9. Select Close Project and select Do not save. Then I repeat for the next year.
Yes, this is a pretty anal description, but if it helps someone else avoid a bunch of frustration, writing this will have been worth it.Statistics:Posted by peterbrecke — 08 Jan 2015 22:24
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