predict.bSpline {splines} | R Documentation |

## Evaluate a Spline at New Values of x

### Description

The `predict`

methods for the classes that inherit from the
virtual classes `bSpline`

and `polySpline`

are used to
evaluate the spline or its derivatives. The `plot`

method for a
spline object first evaluates `predict`

with the `x`

argument missing, then plots the resulting `xyVector`

with
`type = "l"`

.

### Usage

## S3 method for class 'bSpline':
predict(object, x, nseg=50, deriv=0, ...)
## S3 method for class 'nbSpline':
predict(object, x, nseg=50, deriv=0, ...)
## S3 method for class 'pbSpline':
predict(object, x, nseg=50, deriv=0, ...)
## S3 method for class 'npolySpline':
predict(object, x, nseg=50, deriv=0, ...)
## S3 method for class 'ppolySpline':
predict(object, x, nseg=50, deriv=0, ...)

### Arguments

`object` |
An object that inherits from the `bSpline` or the
`polySpline` class. |

`x` |
A numeric vector of `x` values at which to evaluate the
spline. If this argument is missing a suitable set of `x`
values is generated as a sequence of `nseq` segments spanning
the range of the knots. |

`nseg` |
A positive integer giving the number of segments in a set
of equally-spaced `x` values spanning the range of the knots
in `object` . This value is only used if `x` is missing. |

`deriv` |
An integer between 0 and `splineOrder(object) - 1`
specifying the derivative to evaluate. |

`...` |
further arguments passed to or from other methods. |

### Value

an `xyVector`

with components

`x` |
the supplied or inferred numeric vector of `x` values |

`y` |
the value of the spline (or its `deriv` 'th derivative)
at the `x` vector |

### Author(s)

Douglas Bates and Bill Venables

### See Also

`xyVector`

,
`interpSpline`

,
`periodicSpline`

### Examples

ispl <- interpSpline( weight ~ height, women )
opar <- par(mfrow = c(2, 2), las = 1)
plot(predict(ispl, nseg = 201), # plots over the range of the knots
main = "Original data with interpolating spline", type = "l",
xlab = "height", ylab = "weight")
points(women$height, women$weight, col = 4)
plot(predict(ispl, nseg = 201, deriv = 1),
main = "First derivative of interpolating spline", type = "l",
xlab = "height", ylab = "weight")
plot(predict(ispl, nseg = 201, deriv = 2),
main = "Second derivative of interpolating spline", type = "l",
xlab = "height", ylab = "weight")
plot(predict(ispl, nseg = 401, deriv = 3),
main = "Third derivative of interpolating spline", type = "l",
xlab = "height", ylab = "weight")
par(opar)

[Package

*splines* version 2.2.1

Index]