line
Robust Line Fitting

Description

Fits a tukey line.

Usage

line(x, y = NULL)

## S3 method for class 'tukeyline':
print(x, digits = max(3L, getOption("digits") - 3L), ...)

Arguments

x the x coordinates of points. If y is missing, x should be an object implicitly containing x-y data: a 2-column matrix, a list with components named x and y, a complex vector, a ts object, or a numeric vector. See xy.coords for more details.

For the print method, x is an object of class "tukeyline", typically producted by line.

y the y coordinates of points.
digits the maximum number of (significant) digits to use for coefficients of tukey line.
... other optional arguments passed to generic function.

Details

line fits a line through the points using a simple robust algorithm that Tukey described in reference Exploratory Data Analysis. The slope is the slope of the line passing through the x and y medians of the left and right thirds of the data; the intercept is chosen so that the median residual is 0.
Value
line returns a list of class "tukeyline" with following components:

call system call of this function.
coefficients the coefficients, intercept then slope, of the fitted line.
residuals the actual y values minus the fitted values.
fitted.values the y values on the fitted line at the observed x values.
print.tukeyline, like other print methods, returns its x argument invisibly.
References
Tukey, J. W. 1977. Exploratory Data Analysis. Reading, MA: Addison-Wesley Pub.
See Also
lm, lm.fit, xy.coords.
Examples
tukey.line <- with(Sdatasets::fuel.frame, line(Weight, Fuel))
tukey.line
coefficients(lm(Fuel ~ Weight, data=Sdatasets::fuel.frame))
Package stats version 6.1.1-7
Package Index