partykit (version 0.1-2)

party-predict: Tree Predictions

Description

Compute predictions from party objects.

Usage

## S3 method for class 'party':
predict(object, newdata = NULL, \dots)
predict_party(party, id, newdata = NULL, ...)
## S3 method for class 'default':
predict_party(party, id, newdata = NULL, \dots) 
## S3 method for class 'constparty':
predict_party(party, id, newdata = NULL,
    type = c("response", "prob", "node"), FUN = NULL, 
    simplify = TRUE, ...)
## S3 method for class 'simpleparty':
predict_party(party, id, newdata = NULL,
    type = c("response", "prob", "node"), ...)

Arguments

object

objects of class party.

newdata

an optional data frame in which to look for variables with which to predict, if omitted, the fitted values are used.

party

objects of class party.

id

a vector of terminal node identifiers.

type

a character string denoting the type of predicted value returned, ignored when argument FUN is given. For "response", the mean of a numeric response, the predicted class for a categorical response

FUN

a function to compute summary statistics, i.e., constant predictions for each node with argument list (y, w) where y is the response and w are case weights.

simplify

a logical indicating whether the resulting list of predictions should be converted to a suitable vector or matrix (if possible).

...

additional arguments.

Value

• A list of predictions, possibly simplified to a numeric vector, numeric matrix or factor.

Details

The predict method for party objects computes the identifiers of the predicted terminal nodes, either for new data in newdata or for the learning samples (only possible for objects of class constparty). These identifiers are delegated to the corresponding predict_party method which computes (via FUN for class constparty) or extracts (class simpleparty) the actual predictions.

Examples

## fit tree using rpart
  library("rpart")
  rp <- rpart(skips ~ Opening + Solder + Mask + PadType + Panel,
              data = solder, method = 'anova')

  ## coerce to `constparty'
  pr <- as.party(rp)

  ## mean predictions
  predict(pr, newdata = solder[c(3, 541, 640),])

  ## terminal node identifiers
  predict(pr, newdata = solder[c(3, 541, 640),], type = "node")

  ## median predictions
  predict(pr, newdata = solder[c(3, 541, 640),], 
          FUN = function(y, w = 1) median(y))