When calculating the main zone matrix from a zone matrix, you add the matrix values of zones that belong to the same main zone. This applies both to OD demand and skim matrices. The total amount of the matrix values are added to the main zone matrix, the zone matrix is kept.
When disaggregating a main zone matrix you divide the matrix values of the main zones into several matrix values for the individual zones and add them to a zone matrix. The values can be equally distributed. However, you can also weight them. As weighting factors you can use the values of one or two zone matrices or of OD zone attributes.
If you select two weighting factors, the new matrix values are calculated as follows:
where
|
i, j |
Zone indices |
|
i, j |
Main zone indices related to the zone indices |
|
Index(I), Index (J) |
Number of zone indices belonging to the main zone |
|
bij |
Value in the output matrix (zone matrix) |
|
aij |
Value in input matrix (main zone matrix) |
|
wij(1), wij(2) |
two weighting factors |
|
Note: If the denominator of a fraction is zero, weighting will be ignored. |
Use case
You would like to correct a matrix or adjust it using count data. The count data available refers to a rougher zone structure than your network. In this case, you first aggregate the zone matrices, then perform a correction procedure (e.g. TFlowFuzzy) and finally disaggregate the matrix again.
