Changing partition alignment in activity diagrams

In activity diagrams, you can align the partitions and subpartitions vertically or horizontally, or disable the alignment and use them as freeform shapes. By default, the partitions and subpartitions are aligned vertically.

Before you begin

An activity diagram must be open in the Modeling Perspective.


To change the alignment of the partitions, complete one of the following steps:
  • To align the partitions horizontally, right-click in the activity frame; then click Horizontal alignment.
  • To align the partitions vertically, right-click in the activity frame; then click Vertical alignment.
  • To enable freeform partitions, right-click in the activity frame; then click Freeform alignment.
The alignment setting applies to new partitions and subpartitions that you add to the model.


The following table contains two figures that illustrate the arrangement of two partitions, and the corresponding nodes and activity edges, when you align them vertically and horizontally. In each figure, an activity frame, called Activity1, contains two partitions. One partition, called Partition1, contains an action, called OpaqueAction, that is connected to a decision. The second partition, called Partition2, contains OpaqueAction2 and OpaqueAction3, which represent two possible results of the decision. In the first column the partitions are arranged vertically; in the second column they are arranged horizontally.
Vertical alignment of partitions Horizontal alignment of partitions
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You can see an example of freeform partitions in the Example of an activity diagram topic.

Tip: You can also change the flow of the nodes and activity edges within each partition or subpartition. To display the flow within the partition vertically, right-click the shape compartment of the partition; click Vertical flow to add the check mark. To display flow horizontally, right-click the shape compartment; then click Vertical flow to remove the check mark.