circr provides R function to prepare you data to be used in a Null2's circular plot.
The idea is to start from a CSV file like the following
| time | origin | suborigin | destination | subdestination | measure |
|---|---|---|---|---|---|
| 2007 | a1 | a | b2 | b | 17 |
| 2007 | a1 | a | b3 | b | 19 |
| 2008 | a1 | a | b1 | b | 3 |
and get something like
| origin | suborigin | destination | subdestination | 2007 | 2008 |
|---|---|---|---|---|---|
| a1 | a | b2 | b | 17 | 0 |
| a1 | a | b3 | b | 19 | 0 |
| a1 | a | b1 | b | 0 | 3 |