Aggregating matrix objects

This function allows you to group several matrix objects to create one or several new objects. You can use the Aggregate function to rename zones and/or group them into larger units (e.g. districts). The number of rows and columns of a matrix is changed through aggregation.

The new matrix values are calculated with the aid of the following formulas:

Arithmetic mean

Weighted mean

with

qi

Matrix value of ith zone

gi

Weighting of ith zone

n

Number of columns or rows

Example of aggregating matrix objects

The matrix values of the matrix below are aggregated.

Zone allocations and settings:

  • Zone 10 is removed from the matrix
  • Zones 20 and 30 are aggregated and will form the new zone 39
  • The weighted mean is used as aggregate function.
  • The matrix data is weighted using the following matrix.

  • Origin and destination zones of the matrix are aggregated
  • The matrix values of the original matrix are used

The following matrix results.

Matrix values of destination zone 39 were calculated as follows:

Note: If you aggregate a filtered matrix, only the filtered values are aggregated.