predict.earth {earth} | R Documentation |
Predict with an earth
model.
## S3 method for class 'earth' predict(object = stop("no 'object' arg"), newdata = NULL, type = c("link", "response", "earth", "class", "terms"), thresh = .5, trace = FALSE, ...)
object |
An |
newdata |
Make predictions using |
type |
Type of prediction.
One of |
thresh |
Threshold, a value between 0 and 1 when predicting a probability.
Only applies when |
trace |
Default FALSE. Set to TRUE to see which data, subset, etc. |
... |
Unused, but provided for generic/method consistency. |
The predicted values (a matrix for multiple response models).
Except if type="terms"
, then a matrix with each column showing the contribution of a predictor.
Predicting with standard earth models
Use the default type="link"
, or possibly type="class"
.
Actually, the "link"
, "response"
, and "earth"
choices all return the same value unless the glm
argument
was used in the original call to earth
.
Predicting with earth-GLM models
This section applies to earth models with a GLM component, i.e.,
when the glm
argument was used
in the original call to earth
.
The "link"
and "response"
options:
see predict.glm
for a description of these.
In brief: for logistic models
use type="link"
to get log-odds and
type="response"
to get probabilities.
Use option "earth"
to get the linear fit (this gives the prediction you would get
if your original call to earth had no glm
argument).
Predicting with "class"
Use option "class"
to get the predicted class.
With option "class"
, this function first makes predictions with
type="response"
and then assigns the predicted values to classes as follows:
(i) When y
is a logical, predict TRUE if
the predicted probability is greater than thresh
.
(ii) When y
is a numeric, predict TRUE if
the predicted value is greater than thresh
.
Actually, this is identical to the above case,
although thresh
here may legitimately be a value
outside the 0...1 range.
(iii) When y
is a two level factor,
predict the second level if its probability is more than thresh
.
In other words, with the default thresh=.5
predict the most probable level.
(iv) When y
is a three or more level factor,
predict the most probable level (and thresh
is ignored).
Predicting with "terms"
The "terms"
option returns a "link"
response suitable for termplot
.
Only the additive terms and the first response (for multi-response models) are returned.
Also, "terms"
always returns the earth terms, and ignores the GLM component
of the model, if any.
data(trees) a <- earth(Volume ~ ., data = trees) predict(a) # same as a$fitted.values predict(a, c(10,80)) # yields 18.11