Abstractions
Tutorial Exercise 3.2: Using Abstractions to simplify a Layout
Interactive abstractions are used to hide particular parts of
a graph that may be uninteresting or confusing at the moment.
Abstractions are temporary operations that can be undone at
any time.
Select some node in the graph that has at least one child node.
Now you can hide the subgraph of this node by selecting menu
Abstraction/Hide Subgraph.
After doing so, the children of the node are removed from the
visualization and the selected node is drawn with an
icon showing a pair of scissors to emphasize the applied
abstraction:
Node with a hidden subgraph
You can restore the subgraph of the selected node by using menu
Abstraction/Show Subgraph.
Make sure to select a node with a hidden subgraph, otherwise the
show operation is not available.
Try to hide three or four large subgraphs.
You can see that the position of the other nodes is not affected
by this operation, to reserve the space until the subgraph is
shown again.
So maybe a lot of unused space is present in the visualization
after hiding some subgraphs.
Take advance of this space by selecting menu
Layout/Improve Spacing
which gives you in a more compact layout.
Now you can restore the original layout by using menu
Layout/Restore all Subgraphs
to restore all subgraphs in one step.
Because the place of the subgraphs is occupied after
compactification, the layout may not look as it looked before
applying the abstractions, but with the incremental graph layout
that is automatically applied when fading in subgraphs you will get
a quite reasonable layout.
Another abstraction is hiding all the edges of a selected node:
both the incoming (from the parent nodes) and the outgoing edges
(to the child nodes).
The three operations for edge abstractions are also available
in the
Abstraction
menu.
After hiding the edges of a selected node, they are removed from
the graph visualization and the node is drawn with a rectangular
border to emphasize the applied abstraction:
Node with hidden edges
In opposition to subgraph abstractions, applying an edge abstraction
has no effect on the position of nodes and edges, so you can use
it at any time without worrying about losing your layout.
End of Exercise 3.2.
Go back to the Section 3 Overview.
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