Controls for influence diagrams

 

Automatic arc drawing

 

Usage

• BD>control  autoarc =I where I is an integer representing an arc type.

• the default is .

The possible arc types are summarised in Table 11.4. A setting of means only the arcs defined via grid or arc commands will be drawn. Otherwise, arcs between nodes in the adjustment are automatically drawn in the style intended by the value of I. For example, gives simple labelled arcs.

A special case occurs where , meaning that only unlabelled directed arcs are to be drawn. For the sake of speed, in this case no scan-type information of the kind discussed in §21.7 is available automatically, because this information is not required for arc labelling. Thus the operands arcin , arcind , arcout , arcoutd , and arcpc  will not be defined and it will be an error to access them. The noscan  control can always be used to force the production of this information if necessary.  

Set large effect shading size

 

Usage

• BD>control  bigshade =R where is a real number.

• the default is .

The bigshade  control is used to set the proportion of area shaded for node and arc size ratios (diagnostic values). Suppose that the size ratio is p and that . Then the area shaded is . Thus, the larger the value of R, the larger the area shaded. When , the smallshade  value is used instead.  

Redraw node shading

 

Usage

• BD>control  -overshade  switches the control off.

• BD>control  overshade  switches the control on.

• the default is OFF.

The setting of the overshade  control is relevant only when influence diagrams are being drawn, and only when the overwrite  control is switched on and a previous adjustment exists. In these circumstances, it is possible for node shadings for the influence diagram to change from one adjustment to the next. The overshade  control when switched on forces a new node shading to be drawn. Otherwise, the previous node shading is left as it was. This feature will mostly be used to shade nodes in a sequence of adjustments, without losing the shadings at each stage. The overcolour  control is used to set the colour for the overshading.  

Setting overshade colours

 

Usage

• BD>control  overcolour =I where is an integer.

• the default is .

The overcolour  control is used to set the colour used for shading outer node areas representing the overall resolutions for nodes which have been subject to a previous adjustment. This is relevant only when the overshade  control is switched on. Table 11.3 contains a list of available colours.  

Overwrite graphics screen

 

Usage

• BD>control  -overwrite  switches the control off.

• BD>control  overwrite  switches the control on.

• the default is ON.

The setting of the overwrite  control is relevant only when influence diagrams are being drawn. When set on, the graphics screen is not cleared at the end of the command that produced the screen, and further images drawn on the screen will overwrite what is there already. In this way a complex influence diagram, the result perhaps of a succession of adjustments, can be constructed. The graphics screen may be independently cleared at any time by issuing the GCLEAR:  command. When the overwrite  control is switched off, the graphics screen is cleared at the end of the command which caused graphics to be drawn.  

Omit detailed arc calculations

 

Usage

• BD>control  -noinfluence  switches the control off.

• BD>control  noinfluence  switches the control on.

• the default is ON.

The setting of the noinfluence  control determines whether or not adjustments using the ADJUST:  command also scan for the individual effects of adjustment (solitary addition and solitary withdrawal from the overall fit) by each base and element to be used for the adjustment. These are automatically calculated if the influence  option is switched on, as the information calculated is used to label the arcs on the influence diagram. Otherwise, these calculations can significantly slow down operation of the ADJUST:  command. When the control is switched on, the results become available as the operators arcin , arcout , arcind , and arcoutd . See also §11.3.  

Set small effect shading size

 

Usage

• BD>control  smallshade =R where is a real number.

• the default is .

The smallshade  control is used to set the proportion of area shaded for node and arc size ratios (diagnostic values). Suppose that the size ratio is p and that . Then the area shaded is . Thus, the larger the value of R, the larger the area shaded. When , the bigshade  value is used instead.  

Choose arc label length

 

Usage

• BD>control  arclength =R where R is a real number such that .

• by default R=0.

Arc labels have a length which is generally chosen by default to be an appropriate length to fit between two nodes. The default applies at the outset and otherwise can be reinstated by issuing the arclength  control with argument . Otherwise a real value in (0,1) can be supplied, and this forces the arc label to have this length. The entire usable graphics screen is considered to be the unit square.  

Choose arc label width

 

Usage

• BD>control  arcwidth =R where R is a real number such that .

• by default R=0.

Arc labels have a width which is generally chosen by default to be appropriate to the situation. The default applies at the outset and otherwise can be reinstated by issuing the arcwidth  control with argument . Otherwise a real value in (0,1) can be supplied, and this forces the arc label to have this width. The entire usable graphics screen is considered to be the unit square.