Reading an attribute file

You can read attribute values from an attribute file *.att into a Visum network.

1. From the File menu, choose Open file > Attributes.

The Open attributes window opens.

2. Select the desired file.

3. Click the Open button.

The Read attributes window opens.

4. Make the desired changes.

Element	Description
Column	The numbers reflect the order in which the attribute columns are read.
SourceAttributeID	The codes of the attributes read are displayed. Note The codes correspond to the column identifiers of the attribute file.
SourceAttributeName	The long names of the attributes read are displayed.
Target attribute	Use this button to select a target attribute (and a subattribute, if available) for each source attribute in a separate window, into which the values of the source attribute are read (Selection of attributes). Tip Alternatively, you can create a user-defined attribute as target attribute. Notes If no target attribute is selected for a source attribute, the attribute values of the source attribute are not read. If the same target attribute is selected for multiple source attributes, only the attribute values of the source attribute last read (highest column number of the same target attribute) is taken, whose value range corresponds to the value range of the target attribute.
New	Use this button to create a user-defined attribute as target attribute for each source attribute in a separate window (Managing user-defined attributes).
Generate	Via this button you can create simultaneously user-defined attributes for all source attributes to which no target attribute is allocated. Select the data type for the new, user-defined attributes from the selection list in a separate window (Generating user-defined attributes when reading attributes).
Sum up	If this option has been selected, the values of the read source attributes are added to those of the selected target attributes in the existing network. If the option has not been selected, the values of the target attributes are replaced by those of the source attributes. Note This option is only available for numerical target attributes.
Extended	Click this button to define settings for a shortest path search of links between To node and From node in a separate window (Exception: Reading link attributes for links that do not exist within the network). Note We recommend carrying out the shortest path search if link attributes with node-related key attributes are to be read that cannot be allocated to any links within the network.

5. Confirm with OK.

The attribute values of the attribute file are read into the network.

Note: If you read an attribute file, Visum first checks whether a column identifier corresponds to an attribute ID. If this is the case, it is suggested. If this is not the case, for example, because the file contains aliases as attribute names, Visum checks whether it is a valid alias (Specifying an alias for attribute names). If you use the Use aliases option when exporting, the automatic allocation of attribute columns when importing attributes will only be successful if the same definitions exist in the target network as when exporting.

Exception: Reading link attributes for links that do not exist within the network

If you want to read in link attributes with node-related key attributes (From node and To node; i.e. without link number) that cannot be allocated to any links within the network, you can perform a shortest path search between the From nodes and To nodes of the corresponding links.

1. Read in a link attribute file (Reading an attribute file).

The Read attributes window opens.

2. Click the Advanced button.

The Read link attributes: Search parameters window opens.

3. Make the desired changes.

Element	Description
Ignore link	If the option has been selected, attribute values for which no links with the relevant From nodes and To nodes are found in the network are disregarded when reading the file.
Find shortest path	If this option has been selected, a shortest path search From node to To node with the set search parameters is carried out.
Transport system	From the list, select the transport system the shortest path search is to be carried out. Note The list is only available if the Find shortest path option has been selected. Tip You can also carry out the shortest path search for all transport systems defined in the network by selecting All in the list. Blocked links and turns are disregarded.
Use also closed links for routing	If this option has been selected, links actually closed for the transport system are considered open for the transport system. If the option has not been selected, closed links are not regarded for the shortest path search. Note This option is only available if the shortest path search is carried out for one transport system only.
Use also closed turns for routing	If this option has been selected, turns closed for the transport system are considered open for the transport system. If the option has not been selected, closed turns are not regarded for the shortest path search. Note This option is only available if the shortest path search is carried out for one transport system only.
Search criterion	Any numerical link attribute and its subattribute, if applicable, can be selected from the list and can serve as a search criterion. Note The list is only available if the Find shortest path option has been selected.
Attribute data / distribution	From the list, select how attribute values are to be assigned to links that are found within the network. Assign only to the first link If this option has been selected, the attribute data is used just for the first link of the route that was found. Use for all links If this option has been selected, the attribute value is used for all links found within the network between the From-node and the To-node. Note The list is only available if the Find shortest path option has been selected.

4. Confirm with OK.

The settings are applied.