Flow maps show the movement of people, commodities, animals, or other data from one location to another. These maps show data based on routes of travel and vary line thickness to show amount of travel. The greater the movement, the thicker the line. MapViewer can draw lines from centroid to centroid to create a flow map, or associate a data file with a base map of polylines to create a flow map design.
How the starting and ending points are defined depends on two factors. The first is the Primary ID's of the map boundary file and the second is whether you want to connect boundary curves or centroids.
The Connect centroids method connects boundary object centroids based upon starting and ending primary IDs. You can connect the centroids of polygons, polylines, or points. This example will walk through how to create a flow map connecting points.
First, a Pin map is created first using a data file that contains the XY locations of your points, and a PID for each point. Then, the Pin map is converted to a Flow map by loading in a data file that contains a Beginning PID, Ending PID, and Value columns. The PIDs should match the PIDs in the boundary or point file.
Attached below are two data files to use with the steps below for an example:
- Click Map | Create Map | Pin. Select pin.DAT and click Open.
- With the Pin Map selected, click Map | Create Map | Flow. The Pin Map is converted to a Flow Map.
- In the Property Manager, click the General tab,
- Click the Open File button in the Data file field.
- Navigate to flow.DAT and click Open.
- The flow lines are created. You can edit the line properties on the Map tab of the Property Manager.
To create a flow map that connects boundary polygons, you can use these steps:
- Click Map | Create Map | Flow.
- In the Import dialog, select the vector file containing the boundaries and click Open.
- In the Import Options dialog, make changes to the attributes if needed and then click OK.
- In the Open Data File dialog, select the data file and click Open.
- In the Property Manager, click the General tab.
- Select the appropriate data columns for the Start PID field, End PID field, and Variable field
- In the Property Manager, click the Map tab
- Set the Method field to Connect centroids.
- Adjust the remaining settings as desired. For additional information about the available options, see the Flow Map help page by clicking Help | Contents and navigating to Map Types | Flow Map.
Updated October 12, 2018