clear a topic to make it 'unpublished'
I am working on a project where I want to be able to launch the turtlebot gmapping demo immediately after the amcl demo. I do not want to add to a map that I've already been navigating, instead I want to clear the map that was used by the amcl navigation demo and start a new one. The problem I have is that the /map topic seems to hold the values that the navigating demo was using. I don't want to quit ros and start it over again. What I was hoping was that there was some way to clear the map and proceed from there.
How does one clear a topic to the state of emptyness or the state of not being published at all? Can this be done programmatically? Does this make sense?