Pitney Bowes MapInfo Professional - Manual (Page 77)

For example, if you want to find all customers who live within a fifty kilometers radius of Paris, make the
Street layer selectable. If the map also includes a layer of hospitals (which you do not want to include
in the radius search), turn off the Selectable option for the hospital layer.
The Editable or Selectable options only apply to the Map window itself. You can always select objects
using the Select or SQL Select commands regardless of whether a layer is selectable.
Working with Thematic Layers
When you create a thematic map in MapInfo Professional, the thematic shading is added to your map
as a separate layer. It is drawn on top of the layer, from which it gets the raw data. Separating a thematic
layer from its base layer provides you with several important options:
• Graduated symbol thematic maps do not require that your base layer contain point objects. Instead,
graduated symbol objects are built regardless of the map object type. Therefore, even if your base
layer contains region or line objects, you will still be able to create a graduated symbols map.
• You can have multiple thematic layers per base layer. In some cases, you do not have to add another
base layer to the map to create another thematic layer. You can display more than one thematic layer
at a time, as well as perform bivariate thematic mapping.
• You can use Layer Control to turn the display on or off for a given thematic layer. The layer it is based
on can continue to display. You can also set individual zoom layers on thematic maps.
Ordering Thematic Layers
To display thematic layers properly, they must be in a specific order. This is especially important when
you want to display more than one thematic layer at a time. For example, you would want pie or bar
charts for an area map to display on top of regions that are shaded in order to see them.
The following lists the order of map layers from top to bottom (note that map layers are drawn from the
bottom up):
1. Pies, Bars, or Graduated Symbol thematic layer.
2. Dot Density thematic layer.
3. Ranged thematic layer - where Color or Size Attributes are applied.
4. Ranged (or Individual Value) thematic layer - where All Attributes are applied.
5. Major layer or base layer.
6. Grid thematic layer.
When you create a new thematic layer, MapInfo Professional automatically inserts it into its proper place.
• For more information, see Reordering Thematic Layers in the Help System.
Displaying Thematic Layers
You can turn the display on and off for thematic layers the same way you can for other map layers. All
the display settings in Layer Control are also applicable to thematic layers, enabling you to set a zoom
level for each thematic layer. You can also access the Modify Thematic Map dialog box through Layer
Control by double-clicking a Thematic layer.
Thematic layers are always drawn after their base layer. Therefore, they appear above their base layer
in the Layer Control list, and are indented to distinguish them from other map layers.
Thematic layers are displayed in the list with this naming convention:
<Thematic type> with/by <variable-list>
77 MapInfo Professional User Guide
Chapter 3: The Basics of MapInfo Professional