When you collect the data that you want to display in a chart, you might
find that you have not been given all the data values you require. To
display the chart without these values, you would have had to invent some
values, which might give a false impression to your chart.
PGF allows you to omit the values that you do not have; your chart is
still drawn, but the missing values are ignored.
PGF provides the following methods for the ICU and non-ICU user:
- In the ICU Data Entry panels, specify a period (.) in place of a data
value.
- Using the CSxxxx calls in an application program, specify a missing
data value as 10 raised to the power 72 (X'7C90E410').
You can specify missing values for all types of charts except Venn
diagrams. The effect of missing values on the other types of charts is as
described below:
- Histograms - the step is not drawn and there is no gap left between
the adjacent steps.
- Bar and tower charts:
- On a multiple-bar chart, a gap is shown where the missing value
would have appeared.
- On a composite (stacked) or floating bar chart, the bar for the
missing value is not drawn; there is no gap left between the bars.
- Pie charts:
- On a pie chart with percentage values supplied, the slice that
corresponds to the missing value is not drawn; there is no gap
left between the slices.
- On a pie chart with absolute values supplied, the missing value is
not used in calculating the percentages, and the slice for the
missing value is not drawn (again, no gap is left between the
slices).
- Line, surface, and polar charts:
The effect depends on where the missing value occurs:
- If the missing value is the first or last element in a component,
the component is drawn without that element. This means that, for
a line graph or polar chart without shading, the line that
represents the component is shortened; for a surface chart or
polar chart with shading, the shaded area extends only to the
values that are present.
- If a sequence of one or more missing values lies between two
elements that have values, the two elements with values are
connected by a continuous line.
|
GDDM-PGF V2R1.3 Programming Guide and Reference
Copyright IBM Corporation 1990, 2012