Classify attribute (with a legend)

Attributes with many different values (e.g. percentages) are not suited for display with a unique legend. For such attributes this menu choice is necessary or may at least be more suited than the Display attribute menu choice. The process of classifying an attribute involves the following steps:

1. Get colour name definitions

2. Get a list of active themes

3. Get a list of all attributes in the active theme

4. Get the proper data set member definition file

5. Get the definitions of the active theme

6. Get the data set member attribute definition file of the active theme

7. Select the attribute to display

8. Select the legend to use for this attribute

9. Select whether to display legend in colour or grey-scale

10. Update the legend and theme display based on the contents of the selected legend

These steps are described in more detail in the following:

Get colour name definitions

The colour names used by this INSROP GIS function is defined in an AVENUE script called INSROP.RGBColorNameDictionary. These colour name definitions are similar to the UNIX colour name definitions. This step requires no user input.

Get the active theme

If there is more than one active theme, the user is asked to activate only one theme. This step requires no user input.

Get a list of all attributes in the active theme

This step requires no user input.

Get the proper data set member definition file

This step searches for a data set member definition file in the folder where the active theme is stored. If more than one is found, the user is prompted to select the proper data set member definition file. If none is found, INSROP GIS assumes that the data set member attribute definition file is called alias.fld and Step 5 is skipped.

Get the definitions of the active theme

A theme is a data set member, and the data set member definition file from Step 4 may include the theme definitions. Only the Theme-ID is a mandatory definition parameter. If no Theme-ID satisfying the active theme is found, or the Aliasfile column value is empty, INSROP GIS assumes that the data set member attribute definition file is called alias.fld.

Get the data set member attribute definition file of the active theme

If not already existing in the project, this file is added to the project as a table document. To determine whether the file already exists, INSROP GIS checks whether the table name and comments (see Table-Properties) are identical. The table comments are taken from the comment line (Line 2) in the data set member attribute definition file when the table is added to the project. If no suitable data set member attribute definition file is found, the user is prompted for one.

Select the attribute to display

The user is prompted to select one attribute to display.

Select the legend to use for this attribute

The user is presented a list of predefined legends and is prompted to select one.

Select whether to display legend in colour or grey-scale

The user is prompted to confirm whether to use a grey-scale legend or not.

Update the legend and theme display based on the contents of the selected legend

Based on the actual attribute values in the active theme and the attribute value look-up-table, the display of features in the theme and the associated legend is updated.