Charting > Special Topics > Drawing Trendlines in Bubble and Scatter Charts (trendline)

Drawing Trendlines in Bubble and Scatter Charts (trendline)

How to:

The trendline properties draw a trendline and equation label in bubble and scatter charts.

Note: You can also draw a trendline for an individual series, For information, see Series-Specific Properties.

The following code shows the properties and default values for the trendline: 

"trendline": {
	"enabled": false,
	"mode": "undefined",
	"lineStyle": {
		"width": 1,
		"color": "black",
		"dash": ""
		},
	"equationLabel": {
		"visible": false,
		"font": "8pt Sans-Serif",
		"color": "black",
		"mode": "equation"
		}
	}

Syntax: How to Draw a Trendline in Bubble and Scatter Charts 

 "trendline": {  
     "enabled": boolean,
     "mode": "string"
     "lineStyle": {
          "width": number,
          "color": "string",
          "dash": "string"
      },
     "equationLabel": {
         "visible": boolean,
         "font": "string",
         "color": "string",
         "mode": "string"
      }
    }

where:

"enabled": boolean

Enables or disables the trendline. Valid values are:

  • true, which enables the trendline.
  • false, which disables the trendline. This is the default value.
"mode": "string"

Is string that defines the trendline mode (the type of equation used to generate the trendline). Valid values are:

  • "exponential".
  • "geometric".
  • "hyperbolic",
  • "linear".
  • "logarithmic".
  • "logQuadratic".
  • "modExponential".
  • "modHyperbolic".
  • "polynomial".
  • "quadratic".
  • "rational".
  • undefined. This is the default value.
"lineStyle":
Defines the properties of the trendline.
"width": number

Is a number that defines the width of the trendline in pixels. The default value is 1.

"color": "string"

Is a color defined by a color name or numeric specification string that defines the color of the trendline. The default value is "black".

"dash": "string"

Is a string that defines the dash style of the trendline. Use a string of numbers that defines the width of a dash followed by the width of the gap between dashes (for example, dash: "1 1" draws a dotted line). The default value is "", which draws a solid line.

"equationLabel":
Defines the properties of the equation label.
"visible": boolean

Controls the visibility of the equation label. Valid values are:

  • true, which shows the equation label.
  • false, which does not show the equation label. This is the default value.
"font": "string"

Is a string that defines the size, style, and, typeface of the equation label. The default value is "8pt Sans-Serif".

"color": "string"

Is a color for the equation label defined by a color name or numeric specification string. The default value is "black".

"mode": "string"

Is a string that defines the equation label mode. Valid values are;

  • "equation" (displays the equation in the format most appropriate for the type of trendline generated. For a linear trendline, the equation displays in slope intercept form). This is the default value.
  • "r" (displays the correlation coefficient).

Example: Drawing Trendlines in Bubble and Scatter Charts

The following request generates a bubble chart and defines a linear trendline that is a red dashed line and has a green equation label that shows the correlation coefficient: 

GRAPH FILE WF_RETAIL_LITE
SUM  REVENUE_US MSRP_US DISCOUNT_US 
BY PRODUCT_CATEGORY
ON GRAPH PCHOLD FORMAT JSCHART
ON GRAPH SET LOOKGRAPH BUBBLE
ON GRAPH SET STYLE *
INCLUDE=IBFS:/FILE/IBI_HTML_DIR/javaassist/intl/EN/ENIADefault_combine.sty,$
*GRAPH_JS
"trendline": {
	"enabled": true, "mode": "linear",
	"lineStyle": {"width": 2, "color": "red", "dash": "2 4"},
	"equationLabel": {
		"visible": true, "font": "bold 12pt Sans-Serif", 
		"color": "green", "mode": "r"}}            
*END
ENDSTYLE
END

The output is:

 WebFOCUS

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