MapViewer: Selecting Objects, Part 3 

Introduction

Many operations in MapViewer require first selecting an object or objects. Understanding the different ways to select objects is key to using MapViewer efficiently. Part 1 of this article examined some basic ways to select objects. Part 2 looked at some more advanced techniques. This article discusses selecting objects with queries and a new analysis tool that was added in MapViewer 6.

The selection techniques discussed in this article are:

1. Query
2. Query Map Data
3. Query Within Range
4. Bordering Neighbors

Most methods of selecting objects apply only to objects on the active layer. If you have multiple layers, check the status bar or the layer manager to see which is active.

1 - Query

The three different query commands in MapViewer can take several different actions on the results of the query. Selecting the objects is one of those actions and is the focus of this article. However, realize that other actions are also possible.

The Analysis | Query command can be used to select objects based on values stored in their attributes or linked data.

1. Go to Analysis | Query to open the Query dialog.
2. In the center section of the Query dialog, choose the query action (select), the types of objects to query, and the scope of the query.
    
   
   

   Select areas in the map.

3. Enter the query string in the Where text box. You can type a query string directly into this area, or you can build it by double-clicking on elements in the Object Data Column, Object Attribute, Operator, and Function lists above. For example, use the following query string to find counties with a population greater than or equal to 50,000.
    
   
   

   Find objects with a linked data value in the field "POP 2000" >= 50,000.

4. Click OK and the objects satisfying the query condition are selected.

It is possible to build complicated query strings based on multiple data values and/or attributes. Query strings can be saved to and loaded from files, if you have a query you use frequently. The Query History button gives you access to your 15 most recently used query strings.

2 - Query Map Data

The Analysis | Query command described above allows queries based on raw data values. Analysis | Query Map Data instead works with statistical quantities calculated from the data. For example, in a thematic map of population by county, you can use Query Map Data to find the three least-populous counties.
 

3 - Query Within Range

Use the Analysis | Query within Range command to select objects that are within a certain distance of a single selected object. For example, given a pin map of store and customer locations, I can find all customers within 10 miles of a certain store by selecting that store and then using the following query:
 

4 - Bordering Neighbors

The Bordering Neighbors tool is a new feature included in MapViewer 6. It finds and selects area objects that share a border with a single selected area object. To use this tool,

1. Select the single area object whose neighbors you wish to find.
    
   
   

   Phillips County, Arkansas is selected.

2. Go to Analysis | Bordering Neighbors. The neighboring areas are selected in addition to the original area and the Area and Neighbors dialog displays a list of the selected objects. If a data file is linked to the layer, this dialog also allows you to examine the data for each object and to calculate statistics for all of the selected areas.
    
   
   

   The selected areas are listed along with any linked data.
    
   

   

   Phillips County and it's neighbors (Arkansas, Desha, Lee, and Monroe Counties) are now selected.

If you have any questions about MapViewer or this article, please contact us at mapviewersupport@goldensoftware.com.