Joining Your Data to a Map TransCAD Joining Your Data to a Map 2019/5/20

Joining With TransCAD you can make maps from your data, enabling you to visualize the data in new and different ways. To use your data in a map, you join the data to a map layer, matching the records in your file to the features in a geographic file. This creates a joined view. Once you create a joined view, you can use your data in a map in ways such as creating a theme or labeling the map. 2019/5/20

Joined View A joined view is a live link between a map layer an your own data. Creating a joined view does not change your data in any way, but any changes in your data are automatically reflected in the maps you make. Creating a joined view involves three steps: Choose the layer you want to use and display it in a map or dataview. Open a dataview to display your data. Join the layer to your dataview. 2019/5/20

Create a Joined View (USSALES.WRK) This file need to be open. 2019/5/20

Using a Joined View Once you create a joined view, you can: Make thematic maps. The field list in the theme dialog box will contain the fields from the map layer and the fields from your data file. Add labels to maps using any of your data fields. The field list in the label dialog box will contain the fields from the map layer and the fields from your data file. Select records using any combination of fields from the map layer and fields from your data file. Display the joined view in a dataview, sorting the records and rearranging the columns any way you like. Create formula fields that combine data from the map layer and your own data file. Use the Info tool to display data for a map feature. You will see all of the fields in the joined view. 2019/5/20

Dropping a Joined View When you create a joined view by joining a table to a layer, TransCAD keeps the joined view available as long as the layer appears in any open map, dataview, or layout. Sometimes you may want to get rid of a joined view while the layer is still in use. There are some circumstances when you cannot drop a joined view: When the joined view is part of another, more complex joined view. When a field from the joined view is being used in a thematic map. 2019/5/20

Drop a Joined View 2019/5/20

Values That Don’t Match To creat a joined view, the values in one of the columns of the layer must match the values in one of the columns of the dataview. TransCAD automatically handles cases where your data don’t match the records in a map layer. If your data include records that don’t match any of the features of the map, those records will not be part of the joined view. If the map layer has features that don’t have matching records in your data file, the joined view will show that the data for those features are missing. 2019/5/20

Types of Joined Views When you join a layer and a table to create a joined view, there is often a one-to-one correspondence between the records in the layer and the records in the table. Sometimes the layer and the table do not match record for record. There are two distinct possibilities: The layer has several records that match a single record in the table. This is called a many-to-one joined view. The layer has one record that matches several records in the table. This is called a one-to-many joined view. 2019/5/20

Types of Joined Views Usually, TransCAD can automatically tell whether the layer and the data table should be joined one-to-one or one-to-many. If you want to make sure the data are joined the way you want, use the Options tab in the Join dialog box. 2019/5/20

Join Two Tables, Layers, or Joined Views (AVGSALES.WRK) 2019/5/20