Fit splines to data
These functions create mathematical functions from data, using splines.
fitSpline(
formula,
data = parent.frame(),
df = NULL,
knots = NULL,
degree = 3,
type = c("natural", "linear", "cubic", "polynomial"),
...
)formula |
a formula. Only one quantity is allowed on the left-hand side, the output quantity |
data |
a data frame in which |
df |
degrees of freedom (used to determine how many knots should be used) |
knots |
a vector of knots |
degree |
parameter for splines when |
type |
type of splines to use; one of
|
... |
additional arguments passed to spline basis functions
( |
a function of the explanatory variable
f <- fitSpline( weight ~ height, data=women, df=5 ) xyplot( weight ~ height, data=women ) plotFun(f(height) ~ height, add=TRUE) g <- fitSpline( length ~ width, data = KidsFeet, type='natural', df=5 ) h <- fitSpline( length ~ width, data = KidsFeet, type='linear', df=5 ) xyplot( length ~ width, data = KidsFeet, col='gray70', pch=16) plotFun(g, add=TRUE, col='navy') plotFun(h, add=TRUE, col='red')
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