Looking up attribute values

Many graphical displays that can be produced by the system represent some objects having associated thematic data (values of various attributes). For example, on a map such objects are shown by linear or areal symbols or by geometric signs or icons. On a scatter plot or a dot plot an object is represented by a small circle, on a parallel coordinates plot - by a broken line.

There are two ways of viewing attribute values associated with an object. First, the values may be shown in a popup window that appears when the mouse cursor points on the graphical element representing the object (see Figure 1).

Figure 1
Display of attribute values in a popup window. The mouse cursor points on an object in a map. The popup window shows the values associated with this object.

Second, the user may open a so called "persistent object view" (Figure 2). When the user selects an object in any display, the corresponding attribute values are added to the persistent object view and remain displayed until the user explicitly deselects the object. Hence, the persistent object view is independent of mouse movements and can show simultaneously data referring to several objects. Selection and deselection of an object is done by clicking on it or by enclosing it in a rectangular selection frame. On the map in Figure 2 selected objects are marked by black circles. Selected objects are specially marked in all graphical displays to be visually well distinguished from the rest of the objects.

Figure 2
Display of attribute values in a persistent object view included as a subwindow in a map window. Currently selected objects are marked on the map by black circles. The object view shows the attribute values corresponding to these objects.

In order to enable or disable viewing attribute values in a popup window or in a persistent object view, set the corresponding options of the systems (available through the menu item "options").

Important notes about viewing attribute values in a popup window:

Viewing of attribute values in a popup window is by default enabled.
The window is shown only while the mouse keeps pointing on the object in some of the displays and disappears when the mouse moves.
The window shows only values of the attributes that are visualized on the display containing the mouse cursor. Thus, if the cursor points on some dot (circle) in a scatter plot, only the values of the two attributes represented on this scatter plot will be shown.
On a map only data referring to the active layer are shown. To view data from another layer you should make that layer active.

Important notes about the persistent object view:

Persistent viewing of attribute values is by default disabled. It may be enabled by changing the settings of the system (see the menu item "Options").
Objects to add to the object view can be selected from any of the displays currently present on the screen.
Selection and deselection of objects through mouse clicking (in any display) is disabled when mouse click events are used for map manipulation such as visual comparison. Analogously, selection in a map through a frame is disabled when mouse dragging is used for zooming and panning. In order to change the interpretation of mouse click or mouse drag events, use the tool bar of the map window.
Selection of objects in a map is only done in the active layer.
There are two modes of the persistent view: show currently visualized attributes (in all the displays currently present on the screen) or show attributes explicitly selected by the user. In the first mode the attributes are automatically added to or removed from the object view when new displays are created or some displays closed. In the second mode once selected attributes will remain in the object view until being explicitly deselected. To switch between the modes and to select attributes to view, use the corresponding option setting dialog available through the menu item "Options".

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