The GANTT Procedure

Label Data Set

You specify the Label data set using the LABDATA= option in the PROC GANTT statement. This initiates the labeling of the Gantt chart. The Label data set contains the information that provides the means of determining the label strings and their placement positions. As far as possible, the procedure attempts to use the _X, _Y, and _LABEL variables in the Label data set to extract the horizontal position, the vertical position, and the text string, respectively. The Schedule data set acts as a secondary source of information for all Label data set observations that are linked to it. The priority mechanism is described in the section Determining the Vertical Position.

Determining the Vertical Position

You can specify the vertical position for a label string in one of two ways, either directly by using the _Y variable in the Label data set or indirectly by associating the label with an activity or activities. In the latter case, the vertical position is determined by the relative position of the activity on the activity axis of the Gantt chart.

Determining the Horizontal Position

The procedure attempts to determine the horizontal position using the _X variable. You specify the coordinate system for the value of _X with the optional _XSYS variable. A value of DATA or DATAVAL for the _XSYS variable indicates that the unit of measurement is data values. This is also the default coordinate system for _X. A value of PCT or PCTVAL indicates that the unit of measurement is percentage of the procedure output area.

If the _X variable does not exist or its value is missing, the procedure ignores the Label data set observation if the observation is not linked to an activity in the Schedule data set. However, if the label is linked to an activity (either by the LABVAR variable or a value of -1 for _Y, as described previously), the procedure extracts the horizontal position using the _XVAR variable in the Label data set. The _XVAR variable values are names of numeric variables in the Schedule data set. If the _XVAR value is not missing, the horizontal position is the value of the specified variable in the Schedule data set corresponding to the activity. If no such variable exists in the Schedule data set or its value is missing, no label is displayed for this particular (activity, label) link. As with the _X variable, the _XSYS variable names the unit of measurement for the associated Schedule data set variable.

Coordinate Systems

Coordinates can be specified in data values and percentages. It is important to note a significant difference between these two systems when using multiple pages. A data coordinate value is a point along either the time or activity axis, and it can be related to a page number and to a position on that page in the relevant direction. A percentage value, on the other hand, cannot be related to a particular page and, as such, is treated as applicable to every single page. It is possible to mix data and percentage coordinates. That is, the horizontal position can be in data values and the vertical position can be in percentage values, and vice versa. By mixing coordinate systems, you can get as flexible as you want in labeling Gantt charts.

• If both coordinates are in data values, the label is displayed at a specific coordinate on a specific page.

• If the horizontal coordinate is a percentage, the label is displayed at this horizontal position for every page that corresponds to the vertical position. Likewise, if the vertical position is a percentage, the label is displayed at this vertical position for every page that corresponds to the horizontal position. For example, you can display certain headings at the top of the Gantt chart or at the bottom of the Gantt chart by using a data value for the vertical position and a percentage value for the horizontal position.

• If the horizontal and vertical coordinates are both percentages, the label is displayed on every page at the specified coordinate. This feature can be used to display text that appears on every page, much like titles and footnotes, for example.

Determining the Label String

The technique for determining the label string is similar to that of determining the horizontal position.

As far as possible, the procedure attempts to use the _LABEL variable. If the _LABEL variable does not exist or its value is missing, the procedure ignores the label data observation if the observation is not linked to an activity in the Schedule data set. However, if the label is linked to an activity (either by the LABVAR variable or a value of -1 for _Y, as described previously), the procedure extracts the text string from the Schedule data set using the _LVAR variable. The _LVAR variable values are names of variables in the Schedule data set. If the _LVAR value is not missing, the text string is the value of the specified variable in the Schedule data set corresponding to the activity. If no such variable exists in the Schedule data set or if the value is missing, no label is displayed for this particular (activity, label) link.

Note that the _LABEL variable and the Schedule data set variables named by _LVAR are not restricted to be of character type. These variables can be character or numeric, formatted or unformatted. The strings are displayed using the following rules:

• If the variable is of character type, the label is the character string corresponding to the given activity.

• If the variable is of numeric type and formatted, the label is the formatted string.

• If the variable is of numeric type and unformatted, the label is the number displayed as a string with an integer part of up to LABMAXINT= digits and a maximum of MAXDEC= decimal positions. The LABMAXINT= and MAXDEC= options are specified in the PROC GANTT statement and their default values are 16 and 2, respectively.

Optional Information

In addition to specifying the horizontal and vertical coordinates as described previously, you can also specify a relative offset from these values using the _XOFFSET and _YOFFSET variables. These are optional variables and their default values are both 0. The unit of measurement for the _XOFFSET variable is in MININTERVAL units, and the direction of increase is from left to right. The unit of measurement for the _YOFFSET variable is in barheights, and the direction of increase is from top to bottom. When labels are split, the offset variables pertain only to the first piece of the label. The positions of the remaining split pieces are determined from the positioning of the first piece. The adjusted coordinate after taking the offsets into account is what is used for the placement of the string and is known as the referenced coordinate.

You can control the color and font of the label strings using the _CLABEL and _FLABEL variables, respectively. The values for the _CLABEL variable are any valid SAS/GRAPH color names. If the _CLABEL variable does not exist or its value is missing, the value of the CTEXT= option in the CHART statement is used. The values for the _FLABEL variable are any valid SAS/GRAPH font names. If the _FLABEL variable does not exist or its value is missing, the value of the FONT= option in the CHART statement is used.

You can control the height of the label strings with the _HLABEL variable. The units of measurement are in barheights. If the _HLABEL variable does not exist or its value is missing, the default value of 1 is used.

You can specify the angle of the character baseline with respect to the horizontal in degrees using the _ALABEL variable. If the _ALABEL variable does not exist or its value is missing, the default value of 0 is used. You can specify the rotation angle of each character in the string in degrees with the _RLABEL variable. If the _RLABEL variable does not exist or its value is missing, the default value of 0 is used.

You can control the alignment of the string with the _JLABEL variable. Strings can be displayed left-justified, right-justified, or centered at the specified coordinate. By default, all strings are displayed left-justified. The valid values are L or LEFT for left justification, R or RIGHT for right justification, and C or CENTER for centered justification.

The _PAGEBRK variable gives you displaying control when the referenced coordinate of a label coincides with a pagebreak tickmark and the horizontal coordinate is measured in data values. You can specify on which of the two pages you would like the label to be displayed. The default always displays the label on the first page associated with the common tickmark except when the tickmark is the very first tickmark on the Gantt chart. Valid values are 0 (default), 1 (use first page), or 2 (use second page).

Variables in the LABELDATA= data set

The following table lists all the variables associated with the Label data set and their interpretations by the GANTT procedure. The table also lists for each variable its type, the possible values it can assume, and its default value.