MapInfo tips

I’ve had reason to manipulate some spatial data recently using MapInfo Professional, and picked up a few tips that I thought might be useful to someone else one day:

  • You can use SQL conditions that select objects by their spatial properties. Use syntax like: Str$(obj) = “line”, and Str$(obj) = “point”, Str$(obj) = “region” etc.
  • To change the projection, use File / Save Copy As and click the Projection button.
  • Get used to using the arrow keys to pan around the map, and the mousewheel to zoom in and out – this saves having to switch to the Grabber tool all the time to move around.
  • Press “S” to go into “Snap” mode. This is very useful when creating lines, to make sure they attach to nodes (note the nodes don’t have to be in the same layer when your lines snap). When in Snap mode you will see the text “SNAP” in the status bar at the bottom of the MapInfo main window.
  • The menu item Map / Change View is useful to go straight to a given lat/long coordinate. (It centres the view on your entered coordinate). You will need to be careful however if you have multiple layers open that have different coordinates or projections.
  • To merge two different layers:

* First, the tables have to have the same structure. Use Table / Maintenance / Table Structure to add and remove fields as required.
* Then use either Table / Update Column or Table / Append Rows To Table. If using Update Column on node/arc layers (to copy data from the node or arc objects of one table to the corresponding objects on another), I found using Join with Intersects worked best.

  • To separate a single layer that contains nodes and arcs into two layers:

* Run an SQL Select query with the condition Str$(obj) = “line” – this will select only the arcs.
* Then Save the selection to a separate file (which will be the arcs layer), and delete the selected arcs from your original layer (leaving only the nodes).

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