`<bestFitLine>`

The best-fit line for a set of points

<bestFitLine> is a Graphical component that computes a linear regression through a list of points. When nested inside a <graph>, the <bestFitLine> component displays a line.
The equation for the line of best fit can be rendered by accessing the equation property.

Attributes and Properties

Attributes for `<bestFitLine>`

Number display (5)

avoidScientificNotationAdded in 0.7.16

boolean. Default value: false. Whether to render numbers in full decimal form rather than scientific notation.

displayDecimals

integer. Default value: 2. Number of decimal places to display when rendering this number.

displayDigits

integer. Default value: 3. Number of significant digits to display when rendering this number.

displaySmallAsZero

number. Default value: 1e-14. Threshold below which numbers are displayed as zero.

padZeros

boolean. Default value: false. Whether to pad displayed numbers with trailing zeros to fill the requested digits/decimals.

Labels (1)

labelIsName

boolean. Default value: false. Whether to use this component's name as its rendered label.

Other (10)

applyStyleToLabel

boolean. Default value: false. Whether to apply this component's selected style to its label.

data

[ pointList ]. The data points to fit a line to.

labelPosition

keyword. Where the label sits along this line/curve.

Value	Description
`upperRight`Added in 0.7.10	Place the label above and to the right of the line.
`upperLeft`Added in 0.7.10	Place the label above and to the left of the line.
`lowerRight`Added in 0.7.10	Place the label below and to the right of the line.
`lowerLeft`Added in 0.7.10	Place the label below and to the left of the line.
`center` (default)Added in 0.7.10	Place the label at the midpoint of the line.
`top`Added in 0.7.10	Place the label directly above the line.
`bottom`Added in 0.7.10	Place the label directly below the line.
`left`Added in 0.7.10	Place the label directly to the left of the line.
`right`Added in 0.7.10	Place the label directly to the right of the line.

layer

integer. Default value: 0. Z-order layer index used to stack graphical components (higher values render on top).

lineStyleAdded in 0.7.18

keyword. Stroke style for lines.

Value	Description
`solid`	Continuous, unbroken stroke.
`dashed`	Stroke composed of evenly-spaced dashes.
`dotted`	Stroke composed of evenly-spaced dots.

lineWidthAdded in 0.7.18

number. Stroke width for lines, in pixels.

maskLabelAdded in 0.7.21

boolean. Default value: false. Whether to give the label an opaque background so it stays legible when it overlaps an axis, grid line, or another object.

parallelTo

_directionComponent. Direction the line should be parallel to (e.g. another line or vector).

perpendicularTo

_directionComponent. Direction the line should be perpendicular to (e.g. another line or vector).

variables

[ _variableNameList ]. Names of the variables used in the line equation.

Common to all components (9)

copy

reference. Create an independent copy of another component by reference. Enter a references a $name.

disabled

boolean. Default value: false. Whether this component is disabled and cannot be interacted with.

extend

reference. Extend another component by reference, inheriting its children and attributes. Enter a reference as $name.

fixed

boolean. Default value: false. Whether this component's value is fixed and cannot be modified.

fixLocation

boolean. Default value: false. Whether this component's location is fixed (preventing it from being moved while still allowing other modifications).

hide

boolean. Default value: false. Whether to hide this component from the rendered output.

isResponse

boolean. Default value: false. Whether this component is treated as a response for the purposes of assessment.

name

text. The name used to reference this component from elsewhere in the document.

styleNumber

integer. Default value: 1. The style number used to select this component's visual styling from the available style definitions.

Properties for `<bestFitLine name="b">`

Number display (5)

$b.avoidScientificNotationAdded in 0.7.16

boolean. Whether to render numbers in full decimal form rather than scientific notation.

$b.displayDecimals

integer. Number of decimal places to display when rendering this number.

$b.displayDigits

integer. Number of significant digits to display when rendering this number.

$b.displaySmallAsZero

number. Threshold below which numbers are displayed as zero.

$b.padZeros

boolean. Whether to pad displayed numbers with trailing zeros to fill the requested digits/decimals.

Labels (2)

$b.label

label. The label rendered with this component.

$b.labelIsName

boolean. Whether to use this component's name as its rendered label.

Other (23)

$b.applyStyleToLabel

boolean. Whether to apply this component's selected style to its label.

$b.backgroundColor

text. Human-readable name for this component's background color, derived from the active style and theme.

$b.coeff0

math. The constant term in the implicit line equation coeff0 + coeffvar1·x + coeffvar2·y = 0.

$b.coeffvar1

math. The coefficient of the first variable in the implicit line equation coeff0 + coeffvar1·x + coeffvar2·y = 0.

$b.coeffvar2

math. The coefficient of the second variable in the implicit line equation coeff0 + coeffvar1·x + coeffvar2·y = 0.

$b.data

[ math ]. The data points used to compute the best-fit line.

$b.draggable

boolean. Whether the line can be dragged (always false for a best-fit line).

$b.equation

math. The line's equation as a math expression.

$b.labelPosition

text. Where the label sits along this line/curve.

$b.latex

latex. The line's equation rendered as LaTeX.

$b.layer

integer. Z-order layer index used to stack graphical components (higher values render on top).

$b.maskLabelAdded in 0.7.21

boolean. Whether to give the label an opaque background so it stays legible when it overlaps an axis, grid line, or another object.

$b.numDimensions

number. Number of dimensions of the line (always 2 for a best-fit line).

$b.points

[ math ]. Two points the line passes through.

$b.slope

math. The slope of the line (2D only).

$b.styleDescription

text. A textual description of the line's style.

$b.styleDescriptionWithNoun

text. Style description including the noun "line".

$b.text

text. The line's equation rendered as plain text.

$b.textColor

text. Human-readable name for this component's text color, derived from the active style and theme.

$b.textStyleDescription

text. Human-readable description of this component's text styling (color and any background color).

$b.variables

[ _variableName ]. Variable names used in the line's equation.

$b.xintercept

math. The x-intercept of the line.

$b.yintercept

math. The y-intercept of the line.

Common to all components (8)

$b.disabled

boolean. Whether this component is disabled and cannot be interacted with.

$b.doenetML

text. The DoenetML source code that produced this component.

$b.fixed

boolean. Whether this component's value is fixed and cannot be modified.

$b.fixLocation

boolean. Whether this component's location is fixed (preventing it from being moved while still allowing other modifications).

$b.hidden

boolean. Whether this component is hidden from the rendered output.

$b.hide

boolean. Whether to hide this component from the rendered output.

$b.isResponse

boolean. Whether this component is treated as a response for the purposes of assessment.

$b.styleNumber

integer. The style number used to select this component's visual styling from the available style definitions.

Examples

Example: `<bestFitLine>` through 3 points

A <bestFitLine> is rendered through three named <point> components. Note that the data in this example are not specified as fixed and when the points are moved the regression line will update accordingly.

Example: `<bestFitLine>` from user-input

A <bestFitLine> is rendered through three named <point> components. Coordinates for the points are provided by the user with the <mathInput/> component.

Example: Plot data and determine equation

A <bestFitLine> is rendered through an arbitrary number of data points generated with a <callAction> component that adds <point> children to the named <graph>.

The <collect> component gathers the information required from the <graph> to provide to the data attribute of the <bestFitLine> without having to assign individual names to each <point>.

Attribute Examples

Attribute Example: data

The data attribute specifies the data points through which to fit a regression.

Attribute Example: variables

The variables attribute allows customization of the independent and dependent variable name when rendering the equation of the computed regression line.

Property Examples

Property Example: equation

The equation property of the named <bestFitLine> renders the equation of the computed regression line.

Property Example: slope

The slope property of the named <bestFitLine> renders the slope of the computed regression line.

Property Example: coeff0, coeffVar1, coeffVar2

Linear coefficients corresponding to the linear form A x + B y + C = 0 can be obtained with the above properties, where $C =$ coeff0, $B =$ coeffVar2 and $A =$ coeffVar1.

Property Example: xIntercept, yIntercept

Use the xIntercept and yIntercept properties of the named <bestFitLine> to determine the intercepts of the computed regression line.

Property Example: latex

The latex property renders the latex code for rendering the equation of the computed regression line.

Property Example: data

The data property renders two through points computed for the linear regression.

Property Example: variables

The variables property renders the two variables used when rendering the equation for the linear regression.

Property Example: numDimensions

The numDimensions property renders the number of dimensions for the linear regression.

<bestFitLine>