|The GPLOT Procedure|
|Parts of a Plot|
Some terms used with GPLOT procedure are illustrated in GPLOT Procedure Terms and Additional GPLOT Procedure Terms.
GPLOT Procedure Terms
Additional GPLOT Procedure Terms
|About the Input Data Set|
The input data set that is used by the GPLOT procedure must
contain at least one variable to plot on the horizontal axis and one variable
to plot on the vertical axis. Typically, the horizontal axis shows an independent
variable (time, for example), and the vertical axis shows a dependent variable
(temperature, for example). Variables can be character or numeric. Graphs
are automatically scaled to the values of the character data or to include
the values of numeric data, but you can control scaling with procedure options
or with associated AXIS statements.
If the value of either of the plot
variables is missing, the
GPLOT procedure does not include the observation in the plot. If you specify
interpolation with a SYMBOL definition, the plot is not broken at the missing
value. To break the plot line or area fill at the missing value, use the
PLOT statement's SKIPMISS option. SKIPMISS is available only with join or
Exclude data values from a graph by restricting the range of axis values with the VAXIS= or HAXIS= options or with the ORDER= option in an AXIS statement. When an observation contains a value outside of the specified axis range, the GPLOT procedure excludes the observation from the plot and issues a message to the log.
If you specify interpolation with a SYMBOL definition, by default values outside of the axis range are excluded from interpolation calculations and as a result may change interpolated values for the plot. Values that are omitted from interpolation calculations have a particularly noticeable effect on the high-low interpolation methods: HILO, STD, and BOX. In addition, regression lines and confidence limits will represent only part of the original data.
To specify that values out of range are included in
the interpolation calculations, use the MODE= option in a SYMBOL statement.
When MODE=INCLUDE, values that fall outside of the axis range are included
in interpolation calculations but excluded from the plot. The default (MODE=EXCLUDE)
omits observations that are outside of the axis range from interpolation calculations.
See the MODE= option of the SYMBOL statement in SYMBOL Statement for details.
Data points are plotted in the order in which the observations
are read from the data set. Therefore, if you use any type of interpolation
that generates a line, sort your data by the horizontal axis variable.
If your data contain logarithmic values or if the data values vary over a wide range or contain large values, you may want to specify a logarithmic axis for the horizontal or vertical axis. Logarithmic axes can be specified with the AXIS statement options LOGBASE= and LOGSTYLE=. See AXIS Statement for a complete discussion.
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