The network calculator (module 2.41), introduced only a year ago with
release 2.0, has quickly become an indispensable tool for all kind of
network analysis. With release 3.0, two new options become available:
access to transit assignment results and importing of attribute values
from an data table (d241.in).
Results of the transit assignment may now be accessed in network calculations by the use of a temporary link attribute, that the user has to prepare in a separate step before it can be used in calculations. During the preparation step, the user selects one from the following attributes:
The selected link attribute is accumulated over a user specified subset of transit lines. This opens the possibility to analyze transit lines individually, by mode or grouped according to other criteria.
The so prepared attribute appears now in the list of available attributes and may be used freely until the module is left, or until another temporary attribute is prepared.
The second new option is called "import attribute using batch entry". Any of the modifiable link or node attributes may be read in from the batch input file D241.IN. The user specifies which attribute to read in, for which subset of elements to accept new data, and in which fields of the input lines to look for the identifiers (node number for nodes, I- and J-node for links) and the attribute value. Only lines that contain valid identifier and attribute value in the corresponding fields are acted upon, the others are silently ignored. This allows to use also report files (with headers, etc) directly. Of course, punch files created with module 2.41 can be used as well. This new feature also allows to "invert" link attribute vectors, i.e. copy a link attribute from links I-J to links J-I. This is done by punching out the attribute and reading it back with inversed I- and J-node field numbers.