Chapter Contents
Previous
Next
SAS/GRAPH Software: Reference

SYMBOL Statement

The SYMBOL statement defines the characteristics of symbols that display the data plotted by PROC GPLOT and PROC GCONTOUR.

Used by:
GCONTOUR and GPLOT procedures

Global

Assigned by default

Description

SYMBOL statements create SYMBOL definitions, which are used by the GPLOT and GCONTOUR procedures. For the GPLOT procedure, SYMBOL definitions control

For the GCONTOUR procedure, SYMBOL definitions control

If you create SYMBOL definitions, they are automatically applied to a graph by the procedure. If you do not create SYMBOL definitions, these procedures generate default definitions and apply them as needed to your plots.

Syntax

SYMBOL<1...99>
<COLOR=symbol-color>
<MODE=EXCLUDE | INCLUDE>
<REPEAT=number-of-times>
<STEP=distance<units>>
<appearance-option(s)>
<interpolation-option>;

appearance-options can be one or more of these:
BWIDTH=box-width
CI=line-color
CO=color
CV=value-color
FONT=font
HEIGHT=symbol-height<units>
LINE=line-type
POINTLABEL<=(label-description(s)) | NONE>
VALUE=special-symbol | text-string | NONE
WIDTH=thickness-factor

interpolation-option can be one of these:


Options

When the syntax of an option includes units, use one of these:
CELLS character cells
CM centimeters
IN inches
PCT percentage of the graphics output area
PT points.

If you omit units, a unit specification is searched for in this order:

  1. the GUNIT= option in a GOPTIONS statement

  2. the default unit, CELLS.

BWIDTH=box-width
specifies the width of the box generated by either the INTERPOL=BOX or INTERPOL=HILOB option. Box-width can be any number greater than 0. By default, the value of box-width is the same as the value of the WIDTH= option, whose default value is 1. Therefore, if you specify a value for WIDTH= and omit BWDITH=, the width of the box changes accordingly.
Featured in: Example 4. Creating and Modifying Box Plots

CI=line-color
specifies a color for an interpolation line (GPLOT) or a contour line (GCONTOUR). If you omit CI= but specify CV=, CI= assumes the value of CV=. In this case, CI= and CV= specify the same color, which is the same as specifying COLOR= alone.

If you omit CI=, the color specification is searched for in this order:

  1. the CV= option

  2. the COLOR= option

  3. the CSYMBOL= option in a GOPTIONS statement

  4. each color in the colors list sequentially before the next SYMBOL definition is used.

See also: Using Color
Featured in: Example 1. Ordering Axis Tick Marks with SAS Datetime Values

CO=color
specifies a color for

If you omit the CO= option, the search order for a color specification depends on the interpolation method being used.
See also: Using Color
Featured in: Example 5. Filling the Area between Plot Lines and Example 4. Creating and Modifying Box Plots

COLOR=symbol-color
C=symbol-color
specifies a color for the entire definition, unless it is followed by a more explicit specification. For the GPLOT procedure, this includes plot symbols, the plot line, confidence limit lines, and outlines. For the GCONTOUR procedure, this includes contour lines and labels.

Using the COLOR= option is exactly the same as specifying the same color for both the CI= and CV= options.

If COLOR= precedes CI= or CV= in the same statement, CI= or CV= is used instead.

If you do not use COLOR= or CI=, CV=, and CO=, the color specification is searched for in this order:

  1. the CSYMBOL= option in a GOPTIONS statement

  2. each color in the colors list sequentially before the next SYMBOL definition is used.

See also: Using Color

CV=value-color
specifies a color for

If you omit CV= but specify CI=, CV= assumes the value of CI=. In this case, CV= and CI= specify the same color, which is the same as specifying COLOR= alone.

If you omit CV=, the color specification is searched for in this order:

  1. the CI= option

  2. the COLOR= option

  3. the CSYMBOL= option in a GOPTIONS statement

  4. each color in the colors list sequentially before the next SYMBOL definition is used.

See also: Using Color
Featured in: Example 1. Ordering Axis Tick Marks with SAS Datetime Values, Example 5. Filling the Area between Plot Lines, and Example 4. Creating and Modifying Box Plots

FONT=font
F=font
specifies the font for the plot symbol (GPLOT) or contour-label text (GCONTOUR) specified by VALUE=. The font specification can be

By default, no font is specified, and the symbol specified by VALUE= is taken from the special symbol table shown in Special Symbols for Plotting Data Points. To use symbols from the special symbol table, omit FONT=.

You can use FONT= to specify a symbol font, such as Marker, that contains a symbol that you want to use in your plot. In this case, the string specified by VALUE= is the character code for the symbol. For example, this definition specifies a heart: 

symbol font=marker value=N;

You can also use FONT= to specify a text font, such as Swiss. In this case, the string specified by VALUE= appears in the plot: 

symbol font=swiss value=star;

Here, the word "star" is displayed in the plot.

To cancel a font specification and return to the default special symbol table, enter a null value: 

symbol font=, value=star;
See also: the VALUE= option, Specifying Plot Symbols, and SAS/GRAPH Fonts
Featured in: Labeling Contour Lines

HEIGHT=symbol-height<units>
H=symbol-height<units>
specifies the height in number of units of plot symbols (GPLOT) or contour labels (GCONTOUR).

Note:   HEIGHT= affects only the height of the symbols and labels on the plot; it does not affect the height of any symbols that may appear in a legend.  [cautionend]
See also: the SHAPE= option in the LEGEND statement
Featured in: Example 4. Creating and Modifying Box Plots, Example 3. Rotating Plot Symbols through the Colors List, and Labeling Contour Lines

INTERPOL=BOX<option(s)><00...25>
I=BOX<option(s)><00...25>
produces box and whisker plots. The bottom and top edges of the box are located at the sample 25th and 75th percentiles. The center horizontal line is drawn at the 50th percentile (median). By default, INTERPOL=BOX, in which case the vertical lines, or whiskers, are drawn from the box to the most extreme point within 1.5 interquartile ranges. (An interquartile range is the distance between the 25th and the 75th sample percentiles.) Any value more extreme than this is marked with a plot symbol.

Values for option(s) are one or more of these:
F fills the box with the color specified by CV= and outlines the box with the color specified by CO=
J joins the median points of the boxes with a line
T draws tops and bottoms on the whiskers.

In addition, you can specify a percentile to control the length of the whiskers within the range 00 through 25. These are examples of percentile specifications and their effect:
00 high/low extremes. INTERPOL=BOX00 is not the same as the default, INTERPOL=BOX.
01 1st percentile low, 99th high
05 5th percentile low, 95th high
10 10th percentile low, 90th high
25 25th percentile low, 75th high; since the box extends from the 25th to the 75th percentile, no whiskers are produced.

Box Plot shows the type of plot INTERPOL=BOX produces.

Box Plot

[IMAGE]

Note:   If you use HAXIS= or VAXIS= in the PLOT statement or ORDER= in an AXIS definition to restrict the range of axis values, by default any observations that fall outside the axis range are excluded from the interpolation calculation. See the MODE= option  [cautionend]

You cannot use the GPLOT procedure PLOT statement option AREAS= with INTERPOL=BOX.

To increase the thickness of all box plot lines, including the box, whiskers, join line, and top and bottom ticks, use the WIDTH= option.

To increase the width of the box itself, use the BWIDTH= option. By default the value of BWIDTH= is the same as the value of WIDTH=. Therefore, if you specify a value for WIDTH= and omit BWIDTH=, the width of the box changes.

For a scatter effect with the box, use a multiple plot request, as in this example: 

symbol1 i=none v=star color=green;
symbol2 i=box v=none color=blue;
proc gplot data=test;
   plot (y y)*x / overlay;
Featured in: Example 4. Creating and Modifying Box Plots

INTERPOL=HILO<C><option>
I=HILO<C><option>
specifies that a solid vertical line connect the minimum and maximum Y values for each X value. The data should have at least two values of Y for every value of X; otherwise, the single value is displayed without the vertical line.

By default, for each X value, the mean Y value is marked with a tick as shown in High-Low Plot.

To specify high, low, close stock market data, include this option:
C draws tick marks at the close value instead of at the mean value. Specifying C assumes that there are three values of Y (HIGH, LOW, and CLOSE) for every value of X. If more or fewer than three Y values are specified, the mean is ticked. The Y values can be in any order in the input data set.

In addition, you can specify one of these values for option:
B connects the minimum and maximum Y values with bars instead of lines. Use the BWIDTH= option to increase the width of the bars.
J joins the mean values or the close values (if HILOC is specified) with a line. This point is not marked with a tick mark. You cannot use the PLOT statement option AREAS= with INTERPOL=HILOJ.
T adds tops and bottoms to each line.
BJ connects maximum and minimum values with a bar and joins the mean or close values.
TJ adds tops and bottoms to the lines and joins the mean or close values.

High-Low Plot shows the type of plot INTERPOL=HILO produces. Plot symbols in the form of dots have been added to this figure.

High-Low Plot

[IMAGE]

To increase the thickness of all lines generated by the INTERPOL=HILO option, use the WIDTH= option.

Note:   If you use HAXIS= or VAXIS= in the PLOT statement or ORDER= in an AXIS definition to restrict the range of axis values, by default any observations that fall outside the axis range are excluded from the interpolation calculation. See the MODE= option.  [cautionend]
Featured in: Example 1. Ordering Axis Tick Marks with SAS Datetime Values

INTERPOL=JOIN
I=JOIN
connects data points with straight lines. Points are connected in the order they occur in the input data set. Therefore, the data should be sorted by the independent (horizontal axis) variable.

If the data contain missing values, the observations are omitted. However, the plot line is not broken at missing values unless the SKIPMISS option is used.
See also: the SKIPMISS option and Missing Values

INTERPOL=L<degree><P><S>
I=L<degree><P><S>
specifies a Lagrange interpolation to smooth the plot line. Specify one of these values for degree:
1 | 3 | 5 specifies the degree of the Lagrange interpolation polynomial. By default, degree is 1.

In addition, you can specify one or both of these:
P specifies a parametric interpolation
S sorts a data set by the independent variable before plotting its data.

The Lagrange methods are useful chiefly when data consist of tabulated, precise values. A polynomial of the specified degree (1, 3, or 5) is fitted through the nearest 2, 4, or 6 points. In general, the first derivative is not continuous. If the values of the horizontal variable are not strictly increasing, the corresponding parametric method (L1P, L3P, or L5P) is used.

Specifying INTERPOL=L1P, INTERPOL=L3P, or INTERPOL=L5P results in a parametric Lagrange interpolation of degree 1, 3, or 5, respectively. Both the horizontal and vertical variables are processed with the Lagrange method and a parametric interpolation of degree 1, 3, or 5, using the distance between points as a parameter.

INTERPOL=map/plot-pattern
I=map/plot-pattern
specifies that a pattern fill the polygon that has been defined by the data points. Values for map/plot-pattern are

MEMPTY
ME
an empty pattern. EMPTY and E are valid aliases

MSOLID
MS
a solid pattern. SOLID and S are valid aliases

Mdensity<style<angle>>
a shaded pattern.

Density specifies the density of the pattern's shading:
1...5 1 produces the lightest shading and 5 produces the heaviest.

Style specifies the direction of pattern lines:
N parallel lines (the default)
X crosshatched lines.

Angle specifies the starting angle for parallel or crosshatched lines:
0...360 the degree at which the parallel lines are drawn. By default, angle is 0 (lines are parallel to the horizontal axis).

The INTERPOL=map/plot-pattern option only works if the data are structured so that the data points and, consequently, the plot lines form an enclosed area. The plot lines should not cross each other.
See also: PATTERN Statement
Featured in: Example 5. Filling the Area between Plot Lines

INTERPOL=NEEDLE
I=NEEDLE
draws a vertical line from each data point to a horizontal line at the 0 value on the vertical axis or the minimum value on the vertical axis if it is greater than 0. The horizontal line is drawn automatically.

Needle Plot shows the type of plot INTERPOL=NEEDLE produces. Plot symbols are not displayed in this figure.

Needle Plot

[IMAGE]

You cannot use the PLOT statement option AREAS= with INTERPOL=NEEDLE.

INTERPOL=NONE
I=NONE
produces plots with unconnected data points (scatter plots). If no interpolation method is specified in a SYMBOL statement and if the graphics option INTERPOL= is not used, INTERPOL=NONE is the default.

You cannot use the PLOT statement option AREAS= with INTERPOL=NONE.

INTERPOL=R<type><0><CLM | CLI<50...99>>
I=R<type><0><CLM | CLI<50...99>>
specifies that a plot is a regression analysis. By default, regression lines are not forced through plot origins and confidence limits are not displayed.

Type specifies the type of regression. Specify one of these values for type:
L requests linear regression representing the regression equation

Y= [beta] 0 + [beta]1 X

Q requests quadratic regression representing the regression equation

Y= [beta] 0 + [beta]1 X + [beta] 2 X2

C requests cubic regression representing the regression equation

Y= [beta] 0 + [beta] 1 X+ [beta] 2 X 2 + [beta] 3 X3

By default, type is L. The regression line is drawn in the line type specified in the LINE= option. By default, the type of the regression line is 1.

Note:   Specify type if you use either 0, or CLI, or CLM.  [cautionend]

To force the regression line through a (0,0) origin, specify
0 eliminates the [beta] 0 parameter, or intercept, from the regression equation. If the origin is at (0,0), also forces the regression line through the origin. For example, if you specify 0 for a linear regression, the plot line represents the equation

Y= [beta]1 X

Note:   To force the regression line through the origin (0,0) when the data ranges do not place the origin at (0,0), use the GPLOT procedure options HZERO and VZERO (ignored if the data contain negative values), or use HAXIS and VAXIS to specify axes ranges from 0 to maximum data value. If the data ranges contain negative values and HAXIS and VAXIS specify ranges starting at 0, only values within the displayed range are used in the interpolation calculations.  [cautionend]

To display confidence limits, specify one of these:
CLM displays confidence limits for mean predicted values
CLI displays confidence limits for individual predicted values.

You can specify confidence levels from 50% to 99%. By default, the confidence level is 95%. Include a confidence level specification only if you use CLM or CLI.

The line type used for the confidence limit lines is determined by adding 1 to the values of LINE=. By default, the line type of confidence limit lines is 2.

Plot of Regression Analysis and Confidence Limits shows the type of plot INTERPOL=RCCLM95 produces (cubic regression analysis with 95% confidence limits).

Plot of Regression Analysis and Confidence Limits

[IMAGE]

Featured in: Plotting Two Variables

INTERPOL=SM<nn><P><S>
I=SM<nn><P><S>
specifies that a smooth line is fit to data using a spline routine. INTERPOL=SM is a method for smoothing noisy data. The points on the plot do not necessarily fall on the line.

The relative importance of plot values versus smoothness is controlled by nn. Values for nn are
0...99 produces a cubic spline that minimizes a linear combination of the sum of squares of the residuals of fit and the integral of the square of the second derivative (Reinsch 1967)(footnote 1). The greater the nn value, the smoother the fitted curve. By default, the value of nn is 0.

In addition, specify one or both of these:
P specifies a parametric cubic spline
S sorts data by the independent variable before plotting.

INTERPOL=SPLINE<P><S>
I=SPLINE<P><S>
specifies that the interpolation for the plot line use a spline routine. INTERPOL=SPLINE produces the smoothest line and is the most efficient of the nontrivial spline interpolation methods.

Spline interpolation smoothes a plot line using a cubic spline method with continuous second derivatives (Pizer 1975)(footnote 2). This method uses a piecewise third-degree polynomial for each set of two adjacent points. The polynomial passes through the plotted points and matches the first and second derivatives of neighboring segments at the points.

Specify one or both of these:
P specifies a parametric spline interpolation method. This interpolation uses a parametric spline method with continuous second derivatives. Using the method described earlier for the spline interpolation, a parametric spline is fitted to both the horizontal and vertical values. The parameter used is the distance between points

[IMAGE]

If two points are so close together that the computations overflow, the second point is not used.

S sorts a data set by the independent variable before plotting its data.

Note:   When points on the graph are out of range of the axis values, the curve is clipped. If an end point is out of range, no curve is drawn. Out-of-range conditions may be caused by restricting the range of axis values with the HAXIS= or VAXIS= option in the PLOT statement or the ORDER= option in an AXIS definition.  [cautionend]

INTERPOL=STD<1 | 2 | 3><variance><option(s)>
I=STD<1 | 2 | 3><variance><option(s)>
specifies that a solid line connect the mean Y value with ± 1, 2, or 3 standard deviations for each X.

Note:   By default, 2 standard deviations are used.  [cautionend]

The sample variance is computed about each mean, and from it, the standard deviation sy is computed. Variance can be one or both of these:
M computes [IMAGE],
P computes sample variances using a pooled estimate, as in a one-way ANOVA model.

In addition, specify one of these values for option(s):
B connects the minimum and maximum Y values with bars instead of lines.
J connects the means from bar to bar with a line.
T adds tops and bottoms to each line.
BJ connects maximum and minimum values with a bar and joins the mean values.
TJ adds tops and bottoms to the lines and joins the mean values.

Plot of Standard Deviations shows the type of plot INTERPOL=STD produces. A horizontal tick is drawn at the mean. Plot symbols in the form of dots have been added to this figure.

Plot of Standard Deviations

[IMAGE]

Note:   By default, the vertical axis ranges from the minimum to the maximum Y value in the data. If the requested number of standard deviations from the mean covers a range of values that exceeds the maximum or is less than the minimum, the STD lines are cut off at the minimum and maximum Y values. When this cutoff occurs, rescale the axis using VAXIS= in the PLOT statement or ORDER= in an AXIS definition so that the STD lines are shown.  [cautionend]

If you restrict the range of axis values by using HAXIS= or VAXIS= in a PLOT statement or ORDER= in an AXIS definition, by default any observations that fall outside the axis range are excluded from the interpolation calculation. See the MODE= option.

To increase the thickness of all lines generated by the INTERPOL=STD option, use the WIDTH= option.

You cannot use the PLOT statement option AREAS= with INTERPOL=STD.

INTERPOL=STEP<placement><J><S>
I=STEP<placement><J><S>
specifies that the data are plotted with a step function. By default, the data point is on the left of the step, the steps are not joined with a vertical line, and the data are not sorted before processing.

Specify one of these values for placement:
L displays the data point on the left of the step.
R displays the data point on the right of the step.
C displays the data point in the center of the step.

In addition, specify one or both of these:
J produces steps joined with a vertical line.
S sorts unordered data by the independent variable before plotting.

Step Plot shows the type of plot INTERPOL=STEPJR produces. Plot symbols in the form of dots have been added to this figure.

Step Plot

[IMAGE]

LINE=line-type
L=line-type
specifies the line type of the plot line in the GPLOT procedure, or the contour line in the GCONTOUR procedure:
1 a solid line.
2...46 a dashed line.

Line types are shown in Line Types. By default, LINE=1.

MODE=EXCLUDE | INCLUDE
specifies that interpolation calculations exclude or include data values that are outside the range of plot axes. By default, MODE=EXCLUDE, which excludes values outside the axis range from any calculations.

If you control the range of values displayed on an axis by using HAXIS= and VAXIS= in the GPLOT procedure, or ORDER= in an AXIS definition, any data points that lie outside of the range of the axes are discarded before the calculations are done for interpolation lines. This has a particularly noticeable effect on the high-low interpolation methods, which include INTERPOL=HILO, INTERPOL=BOX, and INTERPOL=STD. Regression analysis also represents only part of the original data.
See also: Values Out of Range

POINTLABEL<=(label-description(s)) | NONE>
labels plot points. Label-description(s) defines the appearance or the values of the labels, or both. POINTLABEL without any specified descriptions labels points with the Y value. NONE suppresses the point labels. Label-description(s) can be used to change the variable whose values are used to label points, and/or to change features of the label text, such as the color, font, or size of the text.

Note:   If you do not specify a color on a SYMBOL statement, the symbol definition is rotated through the colors list before the next SYMBOL statement is used. Thus, if your plot contains multiple plot lines and you want to limit your POINTLABEL specification to a single line, you must specify a color on the SYMBOL statement that contains the POINTLABEL description.  [cautionend]

Label-description(s) can be one or more of these:

COLOR=text-color
C=text-color
specifies the color of the label text. The default is the first color from the colors list.

FONT=font | NONE
F=font | NONE
specifies the font for the text. See SAS/GRAPH Fonts for details on specifying font. If you omit FONT=, a font specification is searched for in this order:
  1. the FTEXT= option in a GOPTIONS statement

  2. the default hardware font, NONE.

HEIGHT=text-height <units >
H=text-height <units >
specifies the height of the text characters in number of units. By default, HEIGHT=1 CELL. If you omit HEIGHT=, a text height specification is searched for in this order:
  1. the HTEXT= option in a GOPTIONS statement

  2. the default value, 1.

JUSTIFY=CENTER | LEFT | RIGHT
J=C | L | R
specifies the horizontal alignment of the label text. The default is CENTER. The location of the point label is relative to the location of the corresponding data point.

POSITION=TOP | MIDDLE | BOTTOM
specifies the vertical placement of the label text. The default is TOP. The location of the point label is relative to the location of the corresponding data point.

"#var" | "#x:#y <$char>" | "#y:#x <$char>" | "#x:#y" "$char" | "#y:#x" "$char"
specifies the variable(s) whose values will label the plot points. The variable specification must be enclosed in either single or double quotation marks. The first specified variable must be prefixed with a pound sign (#). If a second variable is specified, it must be prefixed with a colon and a pound sign (:#). Optionally, when you specify both the X and Y variables, you can specify the character to display as the delimiter between variable values in the plot label.

By default if POINTLABEL is specified without naming a label variable, the Y values label the plot points. You can change the default by using "#var" to specify a different variable whose values should label the points. For example, you might specify the name of the X variable. The following option specifies the variable SALES as the variable whose values will label plot points: 

POINTLABEL=("#sales")

Alternatively, you can label the plot points with the values of the X and Y variables, in either order. The order that you specify X and Y in the variable specification determines the order that the values are displayed in the label. The following option specifies variables HEIGHT and WEIGHT; in the label, the value for HEIGHT will be displayed, followed by the value for WEIGHT: 

POINTLABEL=("#height:#weight")
The variables that you specify must be the plot's X and Y variables. Specifying any other variables will cause unexpected labeling.

By default when you specify both the X and Y variables, a colon (:) displays in the label to separate the values in each label. To change the character that displays as the delimiter, use the $ syntax to specify an alternative character. The following option specifies a vertical bar (|) as the delimiter in the label: 

POINTLABEL=("#height:#weight $|")
Within the quotation marks, the $ specification can precede or follow the variable specification, but it must be separated from the variable specification by at least one space. Optionally, the $ specification can be in its own set of quotation marks.

Note:   Specifying a delimiting character with the $ only changes the character that displays in the label. It does not change the syntax of the variable specification, which requires a colon and pound sign (:#) to precede the second variable.  [cautionend]

Specify as many label-description suboptions as you want. Enclose them all within a single set of parentheses, and separate each suboption from the others by at least one space.

REPEAT=number-of-times
R=number-of-times
specifies the number of times that a SYMBOL definition is applied before the next SYMBOL definition is used. By default, REPEAT=1.

The behavior of REPEAT= depends on whether any of the SYMBOL color options (CI=, CV=, CO=, and COLOR=) or the CSYMBOL= graphics option also is used:

See also: Using the SYMBOL Statement

STEP=distance<units>
specifies the minimum distance between labels on contour lines. The value of distance must be greater than zero. By default, STEP=65PCT.

Note:   If you specify units of PCT or CELLS, STEP= calculates the distance between the labels based on the width of the graphics output area, not the height. For example, if you specify STEP=50PCT and if the graphics output area is 9 inches wide, the distance specified is 4.5 inches. A value less than 10 percent is ignored and 10 percent is used instead.  [cautionend]

When you use STEP=, specify the minimum distance that you want between labels. The option then calculates how many labels it can fit on the contour line, taking into account the length of the labels and the minimum distance you specified. Once it has calculated how many labels it can fit while retaining the minimum distance between them, it places the labels, evenly spaced, along the line. Consequently, the space between labels may be greater than what you specify, although it will never be less.

In general, to increase the number of labels from the default, reduce the value of distance.

If the procedure cannot write the label at a particular location on the contour, for example because the contour line makes a sharp turn, the label may be placed farther along the line or omitted. If labels are omitted, a note appears in the log. Specifying a low value for the GCONTOUR procedure's TOLANGLE= option may also cause labels to be omitted, since this forces the procedure to select smoother labeling locations, which may not be available on some contours.
Featured in: Labeling Contour Lines

VALUE=special-symbol | text-string | NONE
V=special-symbol | text-string | NONE specifies:

VALUE=NONE suppresses plot symbols at the data points, or labels on the contour lines.

Values for special-symbol are the names and characters shown in Special Symbols for Plotting Data Points. The special symbol table can be used only if the FONT= option is not used or a null value is specified: 

font=,

Note:   To specify a single quotation mark, you must enclose it in double quotation marks:  [cautionend]

value="'"

To specify a double quotation mark, you must enclose it in single quotation marks: 

value='"'

In some operating environments, punctuation characters may require single quotes.

If you use VALUE=text-string to specify a plot symbol, you must also use the FONT= option to specify a symbol font or a text font. If you specify a symbol font, the characters in the string are character codes for the symbols in the font. If you specify a text font, the characters in the string are displayed. If you specify a text string containing quotes or blanks, enclose the string in single quotes.

For example, if you specify this statement, the plot symbol is the word "plus" instead of the symbol +: 

symbol font=swiss value=plus;
See also: the FONT= option and Specifying Plot Symbols
Featured in: Example 3. Rotating Plot Symbols through the Colors List, Example 4. Creating and Modifying Box Plots, and Labeling Contour Lines

WIDTH=thickness-factor
W=thickness-factor
specifies the thickness of interpolated lines (GPLOT) or contour lines (GCONTOUR), where thickness-factor is a number. The thickness of the line increases directly with thickness-factor. By default, WIDTH=1.

WIDTH= also affects all the lines in box plots (INTERPOL=BOX), high-low plots with bars (INTERPOL=HILOB), and standard deviation plots (INTERPOL=STD). It also affects the outlines of the area generated by the AREAS= option in the PLOT statement of the GPLOT procedure.

Note:   By default, the value specified by WIDTH= is used as the default value for the BWIDTH= option. For example, specifying WIDTH=6 also sets BWIDTH= to 6 unless you explicitly assign a value to BWIDTH=.  [cautionend]
Featured in: Example 1. Ordering Axis Tick Marks with SAS Datetime Values and Example 4. Creating and Modifying Box Plots

Special Symbols for Plotting Data Points

[IMAGE]

Using the SYMBOL Statement

A SYMBOL statement specifies one or more options that indicate the color and other attributes used by the GPLOT procedure or the GCONTOUR procedure. For GPLOT, the main attributes include the plot symbol, interpolation method, and type of plot line. For GCONTOUR, the main attributes include the type of contour lines used and the text used to label those lines.

Note:   SYMBOL statements can only be applied to contour plots when the AUTOLABEL option is specified on GCONTOUR.  [cautionend]

You can define up to 99 different SYMBOL statements. A SYMBOL statement without a number is treated as a SYMBOL1 statement.

SYMBOL definitions can be defined anywhere in your SAS program. They are global and remain in effect until canceled or until you end your SAS session. Once defined, SYMBOL definitions can be

SYMBOL statements generate one or more symbol definitions, depending on how color is used and whether a plot symbol or type of contour line is specified. For more information, see Controlling Consecutive SYMBOL Statements and Using Generated Symbol Sequences.

Although it is common practice, you do not have to start with SYMBOL1, and you do not have to use sequential statement numbers. When assigning SYMBOL definitions, SAS/GRAPH software starts with the lowest-numbered definition and works upward, ignoring gaps in the numbering.

Altering or Canceling SYMBOL Statements

SYMBOL statements are additive. If you define a SYMBOL statement and later submit another SYMBOL statement with the same number, the new SYMBOL statement defines or cancels only the options that are included in the new statement. Options that are not included in the new statement are not changed and remain in effect.

Assume you define SYMBOL4 as: 

symbol4 value=star cv=red height=4;

The following statement cancels only HEIGHT= without affecting the rest of the definition: 

symbol4 height=;

Add or change options in the same way. This statement adds an interpolation method to SYMBOL4: 

symbol4 interpol=join;

This statement changes the color of the plot symbol from red to blue: 

symbol4 cv=blue;

After all these modifications, SYMBOL4 has these characteristics: 

symbol4 value=star cv=blue interpol=join;

Cancel individual SYMBOL statements by defining a SYMBOL statement of the same number without options (a null statement): 

symbol4;

Canceling one SYMBOL statement does not affect any other SYMBOL definitions. To cancel all current SYMBOL statements, use RESET= in a GOPTIONS statement: 

goptions reset=symbol;

Specifying RESET=GLOBAL or RESET=ALL cancels all current SYMBOL definitions as well as other settings.

To display current SYMBOL definitions in the LOG window, use the GOPTIONS procedure with the SYMBOL option: 

proc goptions symbol nolist;
run;

Controlling Consecutive SYMBOL Statements

If you specify consecutively numbered SYMBOL statements and you want SAS/GRAPH to use each definition only once, use color specifications to ensure each SYMBOL statement generates only one symbol definition. You can

For more information on specifying colors for symbol definitions, see Using Color.

If you do not use color to limit a SYMBOL statement to a single symbol definition, SAS/GRAPH generates multiple symbol definitions from that statement by rotating the current definition through the colors list (for more details, see Using Generated Symbol Sequences). Because SAS/GRAPH uses symbol definitions in the order they are generated, this means that the nth symbol definition applied to a graph does not necessarily correspond to the SYMBOLn statement.

For example, assuming no color is specified on the CSYMBOL= graphics option, these statements generate four definitions: 

goptions colors=(red blue green);
symbol1 value=star;
symbol2 value=square color=yellow;

Because no color is specified on SYMBOL1, SAS/GRAPH rotates the symbol definition through the colors list, which has three colors. Thus, SYMBOL1 defines the first three applied symbol definitions, and SYMBOL2 defines the 4th:

Sequence Number Source Characteristics: Color Symbol
1 SYMBOL1 red star
2 SYMBOL1 blue star
3 SYMBOL1 green star
4 SYMBOL2 yellow square

In this case, if a graph needs only three symbols, the SYMBOL2 definition is not used.

To make the nth applied symbol definition correspond to the SYMBOLn statement, limit each SYMBOL statement to a single color, using one of the techniques listed at the beginning of this section.

Setting Definitions for PROC GPLOT

The following topics apply only for SYMBOL statements used with PROC GPLOT:


Specifying Plot Symbols

The VALUE= option specifies the plot symbols that PROC GPLOT uses to mark the data points on a plot. Plot symbols can be

By default, the plot symbol is the + symbol. To specify a special symbol, use VALUE= to specify a name or a character from Special Symbols for Plotting Data Points: 

symbol1 value=hash color=green;
symbol2 value=) color=blue;

This example uses color to ensure each SYMBOL statement generates only one definition. You can omit color specifications to let SAS/GRAPH rotate symbol definitions through the colors list. For details, see Using Generated Symbol Sequences.

To use plot symbols other than those in Special Symbols for Plotting Data Points, use the FONT= option to specify a font for the plot symbol. If the font is a symbol font, such as Marker, the string specified with the VALUE= option is the character code for the symbol to be displayed. If the font is a text font, the string specified with VALUE= is displayed as the plot symbol. (See VALUE= and FONT=.)

This table illustrates some of the ways you can define a plot symbol:

[IMAGE]


Specifying a Default Interpolation Method

The INTERPOL= option in a GOPTIONS statement specifies a default interpolation method to be used with all SYMBOL definitions. This default interpolation method is in effect unless you specify a different interpolation in a SYMBOL statement. If the GOPTIONS statement does not specify an interpolation method, the default for each SYMBOL statement is NONE.

Sorting Data with Spline Interpolation

If you want the GPLOT procedure to sort by the horizontal axis variable before plotting, add the letter S to the end of any of the spline interpolation methods (INTERPOL=L, INTERPOL=SM, and INTERPOL=SPLINE). For example, suppose you want to overlay three plots (Y1*X1, Y2*X2, and Y3*X3) and for each plot, you want the X variable sorted in ascending order. Use these statements: 

symbol1 i=splines c=red;
symbol2 i=splines c=blue;
symbol3 i=splines c=green;

proc gplot;
   plot y1*x1 y2*x2 y3*x3 / overlay;
run;

Using Color

Generally, there are two ways to explicitly specify color for SYMBOL statements:

You can also let SAS/GRAPH rotate symbol definitions through the colors list. For details, see Using Generated Symbol Sequences.

Specifying Colors with SYMBOL Statements

The SYMBOL statement has these options for specifying color:

CV= and CI= have the same effect as using COLOR= when they are used in these ways:

In general, CI=, CV=, and CO= color specific areas of the symbol. Use these options to produce symbols and plot lines of different colors without having to overlay multiple plot pairs. For example, if you request regression analysis with confidence limits, use this statement to assign red to the plot symbol, blue to the regression lines, and green to the confidence limit lines: 

symbol cv=red ci=blue co=green;

The COLOR= option colors the entire symbol or those portions of it not colored by one of the other color options. If COLOR= precedes CI= or CV=, the CI= or CV= specification is used instead. If none of the SYMBOL color options is used, color specifications are searched for in this order:

  1. the CSYMBOL= option in a GOPTIONS statement

  2. each color in the colors list sequentially before the next SYMBOL definition is used.

CAUTION:
If no color options are used, the SYMBOL definition cycles through each color in the colors list.   [cautionend]

If the SYMBOL color options and the CSYMBOL= graphics option are not used, the SYMBOL definition cycles through each color in the colors list before the next definition is used. For details, see Using Generated Symbol Sequences.

Specifying Color with CSYMBOL=

The CSYMBOL= option on the GOPTIONS statement specifies the default color to be used by all SYMBOL definitions: 

goptions csymbol=green;
symbol1 value=star;
symbol2 value=square;

In this example, both SYMBOL statements use green.

CSYMBOL= is overridden by any of the SYMBOL statement color options. See Using Color for details.

If more SYMBOL definitions are needed, SAS/GRAPH returns to generating default symbol sequences.

Specifying Line Types

To specify the type of line for plot or contour lines, use the LINE= option to specify a number from 1 through 46. Line Types shows the line types represented by these numbers. By default, the line type is 1 for plot and contour lines, and 2 for confidence limit lines.

Line Types

[IMAGE]

Note:   These line types also are used by other statements and procedures. Some options accept a line type of 0, which produces no line.  [cautionend]

Using Generated Symbol Sequences

Symbol sequences are sets of SYMBOL definitions that are automatically generated by SAS/GRAPH software if any of these conditions is true:

If REPEAT= is also used, the resulting SYMBOL definition is repeated the specified number of times.

Default Symbol Sequences

Default symbol sequences are generated by rotating symbol definitions through the current colors list.

Each time a default definition is required, SAS/GRAPH takes the first default plot symbol or line type and uses it with the first color in the colors list. If more than one definition is required, it uses the same plot symbol or line type with the next color in the colors list and continues until all the colors have been used once. If more definitions are needed, SAS/GRAPH selects the second default plot symbol or line type and rotates it through the colors list. It continues in this fashion, selecting default plot symbols or line types and cycling them through the colors list until all the required definitions are generated.

If a color has been specified with the CSYMBOL= option on the GOPTIONS statement, each default plot symbol or line type is used once with the specified color, and the colors in the colors list are ignored.

Symbol Sequences Generated from SYMBOL Statements

If a SYMBOL statement does not specify color, and if the CSYMBOL= graphics option is not used, the symbol definition is rotated through every color in the colors list before the next SYMBOL definition is used: 

goptions colors=(blue red green);
symbol1 cv=red i=join;
symbol2 i=spline v=dot;
symbol3 cv=green v=star;

Here, the SYMBOL1 statement generates the first SYMBOL definition. The SYMBOL2 statement does not include color, so the first default plot symbol is rotated through all colors in the colors list before the SYMBOL3 statement is used. This table shows the colors and symbols that would be used if nine symbol definitions were required for PROC GPLOT:

Sequence Number Source Characteristics: Color Symbol Interpolation
1 SYMBOL1 cv=red first default join
2 SYMBOL2 color=blue dot spline
3 SYMBOL2 color=red dot spline
4 SYMBOL2 color=green dot spline
5 SYMBOL3 cv=green star NONE
6 first default color=blue first default default
7 first default color=red first default default
8 first default color=green first default default
9 second default color=blue second default default

Notice that after the SYMBOL statements are exhausted, the procedure begins using the default definitions (sequences 6 through 9). Each plot symbol from the default list is rotated through all colors in the colors list before the next plot symbol is used. Also, SYMBOL1 does not specify a plot symbol, so the default sequencing provides the first default symbol (a + sign). When sequencing resumes in sequence number 6, it starts at the beginning again, selecting the first default plot symbol and rotating it through the colors list.

If you use REPEAT= but no color, the sequence generated by cycling the definition through the colors list is repeated the number of times specified by REPEAT=. For example, these statements define a colors list and illustrate the effect of REPEAT= on SYMBOL statements both with and without explicit color specifications: 

goptions colors=(blue red green);
symbol1 color=gold repeat=2;
symbol2 value=star color=cyan;
symbol3 value=square repeat=2;

Here, SYMBOL1 is used twice, SYMBOL2 is used once, and SYMBOL3 rotates through the list of three colors and then repeats this cycle a second time:

Sequence Number Source Characteristics: Color Symbol Interpolation
1 SYMBOL1 gold first default default
2 SYMBOL1 gold first default default
3 SYMBOL2 cyan star default
4 SYMBOL3 blue square default
5 SYMBOL3 red square default
6 SYMBOL3 green square default
7 SYMBOL3 blue square default
8 SYMBOL3 red square default
9 SYMBOL3 green square default

FOOTNOTE 1:  Reinsch, C.H. (1967), "Smoothing by Spline Functions," Numerische Mathematik, 10, 177-183. [arrow]

FOOTNOTE 2:  Pizer, Stephen M. (1975), Numerical Computing and Mathematical Analysis, Chicago: Science Research Associates, Inc., Chapter 4. [arrow]


Chapter Contents
Previous
Next
Top of Page

Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.