predict.loess
Predict Loess Curve or Surface
Predictions from a loess fit, optionally with standard errors.
- Keywords
- smooth
Usage
# S3 method for loess
predict(object, newdata = NULL, se = FALSE,
na.action = na.pass, …)Arguments
- object
an object fitted by
loess.- newdata
an optional data frame in which to look for variables with which to predict, or a matrix or vector containing exactly the variables needs for prediction. If missing, the original data points are used.
- se
should standard errors be computed?
- na.action
function determining what should be done with missing values in data frame
newdata. The default is to predictNA.- …
arguments passed to or from other methods.
Details
The standard errors calculation is slower than prediction.
When the fit was made using surface = "interpolate" (the
default), predict.loess will not extrapolate -- so points outside
an axis-aligned hypercube enclosing the original data will have
missing (NA) predictions and standard errors.
Value
If se = FALSE, a vector giving the prediction for each row of
newdata (or the original data). If se = TRUE, a list
containing components
the predicted values.
an estimated standard error for each predicted value.
the estimated scale of the residuals used in computing the standard errors.
an estimate of the effective degrees of freedom used in estimating the residual scale, intended for use with t-based confidence intervals.
Predictions from infinite inputs will be NA since loess does not support extrapolation.
Note
Variables are first looked for in newdata and then searched for
in the usual way (which will include the environment of the formula
used in the fit). A warning will be given if the
variables found are not of the same length as those in newdata
if it was supplied.
See Also
Examples
library(stats)
# NOT RUN {
cars.lo <- loess(dist ~ speed, cars)
predict(cars.lo, data.frame(speed = seq(5, 30, 1)), se = TRUE)
# to get extrapolation
cars.lo2 <- loess(dist ~ speed, cars,
control = loess.control(surface = "direct"))
predict(cars.lo2, data.frame(speed = seq(5, 30, 1)), se = TRUE)
# }