The NETDRAW Procedure

Getting Started

The first step in defining a project is to make a list of the activities in the project and determine the precedence constraints that need to be satisfied by these activities. It is useful at this stage to view a graphical representation of the project network. In order to draw the network, you specify the nodes of the network and the precedence relationships among them. Consider the software development project that is described in the "Getting Started" section of Chapter 2, "The CPM Procedure." The network data are in the SAS data set SOFTWARE, displayed in Figure 5.1.

Software Project

Data Set SOFTWARE

Obs	descrpt	duration	activity	succesr1	succesr2
1	Initial Testing	20	TESTING	RECODE
2	Prel. Documentation	15	PRELDOC	DOCEDREV	QATEST
3	Meet Marketing	1	MEETMKT	RECODE
4	Recoding	5	RECODE	DOCEDREV	QATEST
5	QA Test Approve	10	QATEST	PROD
6	Doc. Edit and Revise	10	DOCEDREV	PROD
7	Production	1	PROD

Figure 5.1: Software Project

The following code produces the network diagram shown in Figure 5.2.

   pattern1 v=e c=green;
   title f=swiss 'Software Project';
   proc netdraw graphics data=software;
      actnet / act=activity
               succ=(succesr1 succesr2)
               pcompress separatearcs
               font=swiss;
      run;

Figure 5.2: Software Project

The procedure determines the placement of the nodes and the routing of the arcs on the basis of the topological ordering of the nodes and attempts to produce a compact diagram. You can control the placement of the nodes by specifying explicitly the node positions. The data set SOFTNET, shown in Figure 5.3, includes the variables _X_ and _Y_, which specify the desired node coordinates. Note that the precedence information is conveyed using a single SUCCESSOR variable unlike the data set SOFTWARE, which contains two SUCCESSOR variables.

Software Project

Data Set SOFTNET

Obs	descrpt	duration	activity	succesor	_x_	_y_
1	Initial Testing	20	TESTING	RECODE	1	1
2	Meet Marketing	1	MEETMKT	RECODE	1	2
3	Prel. Documentation	15	PRELDOC	DOCEDREV	1	3
4	Prel. Documentation	15	PRELDOC	QATEST	1	3
5	Recoding	5	RECODE	DOCEDREV	2	2
6	Recoding	5	RECODE	QATEST	2	2
7	QA Test Approve	10	QATEST	PROD	3	3
8	Doc. Edit and Revise	10	DOCEDREV	PROD	3	1
9	Production	1	PROD		4	2

Figure 5.3: Software Project: Specify Node Positions

The following code produces a network diagram (shown in Figure 5.4) with the new node placement.

   title2 h=1.5 f=swiss 'Controlled Layout';
   proc netdraw graphics data=softnet;
      actnet / act=activity
               succ=(succesor)
               pcompress
               font=swiss;
      run;

Figure 5.4: Software Project: Controlled Layout

Software Project

Project Schedule

descrpt	activity	succesr1	succesr2	duration	E_START	E_FINISH	L_START	L_FINISH	T_FLOAT	F_FLOAT
Initial Testing	TESTING	RECODE		20	01MAR92	20MAR92	01MAR92	20MAR92	0	0
Prel. Documentation	PRELDOC	DOCEDREV	QATEST	15	01MAR92	15MAR92	11MAR92	25MAR92	10	10
Meet Marketing	MEETMKT	RECODE		1	01MAR92	01MAR92	20MAR92	20MAR92	19	19
Recoding	RECODE	DOCEDREV	QATEST	5	21MAR92	25MAR92	21MAR92	25MAR92	0	0
QA Test Approve	QATEST	PROD		10	26MAR92	04APR92	26MAR92	04APR92	0	0
Doc. Edit and Revise	DOCEDREV	PROD		10	26MAR92	04APR92	26MAR92	04APR92	0	0
Production	PROD			1	05APR92	05APR92	05APR92	05APR92	0	0

Figure 5.5: Software Project Schedule

While the project is in progress, you may want to use the network diagram to show the current status of each activity as well as any other relevant information about each activity. PROC NETDRAW can also be used to produce a time-scaled network diagram using the schedule produced by PROC CPM. The schedule data for the software project described earlier are saved in a data set, INTRO1, which is shown in Figure 5.5.

To produce a time-scaled network diagram, use the TIMESCALE option in the ACTNET statement, as shown in the following program. The MININTERVAL= and the LINEAR options are used to control the time axis on the diagram. The ID=, NOLABEL, and NODEFID options control the amount of information displayed within each node. The resulting diagram is shown in Figure 5.6.

   title2 h=1.5 f=swiss 'Time-Scaled Diagram';
   proc netdraw graphics data=intro1;
      actnet / act=activity succ=(succ:)
               separatearcs pcompress font=swiss htext=2
               timescale linear frame mininterval=week
               id=(activity duration) nolabel nodefid;
      run;

Figure 5.6: Software Project: Time-Scaled Network Diagram

Several other options are available to control the layout of the nodes, the appearance of the network, and the format of the time axis. For projects that have natural divisions, you can use the ZONE= option to divide the network into horizontal zones or bands. For networks that have an embedded tree structure, you can use the TREE option to draw the network like a tree laid out from left to right, with the root at the left edge of the diagram; in graphics mode, you can obtain a top-down tree with the root at the top of the diagram. For cyclic networks you can use the BREAKCYCLE option to allow the procedure to break cycles. All of these options are discussed in detail in the following sections.

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