Process Flow Diagram Logic

Subdiagrams

Some process flow diagrams may be quite complex. To help control the process flow, you can create subdiagrams and collapse a set of nodes and connections into a single node icon. Subdiagrams can be opened to display the complete structure of the process flow diagram.

Note: You cannot uncondense the nodes in a subdiagram. [cautionend]

There are two major approaches to creating subdiagrams:

You know in advance that you will use a subdiagram. First, you add a Subdiagram node, and then add nodes within the subdiagram. See Subdiagram Example 1.
You realize later that if a particular set of nodes were condensed into a subdiagram, then the process flow would be much easier to control. See Subdiagram Example 2.

Subdiagram Example 1

Suppose you want a process flow diagram to contain a subdiagram for the following nodes: Sampling, Data Partition, Filter Outliers, and Transform Variables.

To create a subdiagram for these nodes, follow these steps:

Add and define any predecessor nodes from the Tools Palette that you do not want as part of the subdiagram to the Diagram Workspace.
Add a Subdiagram node to the process flow diagram.
Connect the predecessor node to the Subdiagram node and then open the Subdiagram node by double-clicking the node icon. Alternatively, you can right-click the node icon and select Open.

Within the Subdiagram node are Enter and Exit nodes, which by default are connected.
Cut the connection between the Enter and Exit nodes by right-clicking the connection arrow and selecting the Delete pop-up menu item.

Note: The Enter and Exit nodes are connected to allow for independent subdiagrams.
Move the Enter and Exit nodes to the appropriate locations in the process flow diagram, and then add and connect the desired nodes.
Condense the subdiagram, by using the View pull-down menu (or the pop-up menu) to select Up One Level.

Note: When a subdiagram has been defined, a keyhole appears beside the Subdiagram node. To open the subdiagram, you can select the keyhole or you can double-click the node icon.
Position the Subdiagram node in the appropriate location within the process flow diagram, and then connect the Subdiagram node to the appropriate nodes.

This example process flow diagram has an Input Data Source node that is connected to the Subdiagram node, which in turn connects to a Neural Network node and a Regression node. The resulting models are compared and assessed in an Assessment node.

Note: You can clone a node if you need to use it often in the project. See Cloning a Node for an example.

Subdiagram Example 2

In this example, you are developing a process flow diagram:

[Example of process flow diagram without subdiagram: Input data Source connected to Sampling connected to Data Partition connected to Filter Outliers connected to Transform variables, double connected to Neural and Regression nodes, both connected to Assessment node.]

You realize that you could create a subdiagram to contain the following nodes: Sampling, Data Partition, Filter Outliers, and Transform Variables. By condensing these nodes into a subdiagram, you can more easily view other portions of the complete process flow diagram. To create a subdiagram for these nodes, follow these steps:

Select the first node to be included in the subdiagram. A box appears around the selected node (for this example, the Sampling node).
Place the mouse pointer on the arrow that connects the node that you selected in step 1 and the second node to be included in the subdiagram, then CTRL-click or SHIFT-click on the arrow. The selected arrow changes from an arrow to a line segment.
CTRL-click or SHIFT-click on the second node that you want to include in the subdiagram.
Repeat steps 2 and 3 until all nodes and arrows that you want to place in the subdiagram are selected. Note that for large process flow diagrams that contain many nodes only the nodes and arrows that are selected are used to create the subdiagram.

Note: As an alternative to steps 1 through 4, you can select all the multiple nodes and arrows at one time. That is, place the mouse pointer in the process flow diagram near the nodes to be included in the subdiagram (where "near" is on one side of the set of node icons and either above or below the node icons), click and hold the left mouse button, and stretch the dotted box around the appropriate node icons.
Use the main menu to select Edit Create subdiagram A dialog box appears that asks you to verify that the currently selected nodes and arrows are to be condensed into a subdiagram.

If you click Cancel, then the subdiagram is not created. If you click OK, then the subdiagram is created, and a subdiagram node icon replaces the selected nodes and arrows.
To open the Subdiagram node, double-click on the node icon or select the keyhole.
Add endpoints (a pair of nodes that consist of an Enter node and an Exit node) to the subdiagram to indicate where information enters the subdiagram and where it exits the subdiagram. To add endpoints, right-click on an open area of the Diagram Workspace and select Add endpoints. By default, the Enter node is connected to the Exit node. Cut the connection between the Enter and Exit nodes, and then position the Enter node to the left of the subdiagram (so that it precedes the subdiagram) and the Exit node to the right of the subdiagram (so that it follows the subdiagram). Connect the Enter node to the subdiagram (the connection arrow should point to the subdiagram), and connect the subdiagram to the Exit node (the connection arrow should point to the Exit node).
Condense the subdiagram by using the View pull-down menu (or the pop-up menu) to select Up One Level.
Connect the Subdiagram node to the appropriate nodes. In this example, an Input Data Source node passes information to the Subdiagram node, which passes information to the Regression and Neural Network nodes, which in turn pass information to the Assessment node.

You cannot uncondense the nodes in a subdiagram. There is no restriction on how many Subdiagram nodes you can nest in the process flow diagram.

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