evaluate {recommenderlab}

Evaluate a Recommender Models

Description

Evaluates a single or a list of recommender model given an evaluation scheme and return evaluation metrics.

Usage

evaluate(x, method, ...)

## S4 method for signature 'evaluationScheme,character'
evaluate(x, method, type="topNList",
  n=1:10, parameter=NULL, progress = TRUE, keepModel=FALSE)
## S4 method for signature 'evaluationScheme,list'
evaluate(x, method, type="topNList",
  n=1:10, parameter=NULL, progress = TRUE, keepModel=FALSE)

Arguments

x

an evaluation scheme (class "evaluationScheme").

method

a character string or a list. If a single character string is given it defines the recommender method used for evaluation. If several recommender methods need to be compared, method contains a nested list. Each element describes a recommender method and consists of a list with two elements: a character string named "name" containing the method and a list named "parameters" containing the parameters used for this recommender method. See Recommender for available methods.

type

evaluate "topNList" or "ratings"?

n

a vector of the different values for N used to generate top-N lists (only if type="topNList").

parameter

a list with parameters for the recommender algorithm (only used when method is a single method).

progress

logical; report progress?

keepModel

logical; store used recommender models?

...

further arguments.

Details

The evaluation uses the specification in the evaluation scheme to train a recommender models on training data and then evaluates the models on test data. The result is a set of accuracy measures averaged over the test users. See calcPredictionAccuracy for details on the accuracy measures and the averaging. Note: Also the confusion matrix counts are averaged over users and therefore not whole numbers.

See vignette("recommenderlab") for more details on the evaluaiton process and the used metrics.

Value

If a single recommender method is specified in method, then an object of class "evaluationResults" is returned. If method is a list of recommendation models, then an object of class "evaluationResultList" is returned.

See Also

calcPredictionAccuracy, evaluationScheme, evaluationResults. evaluationResultList.

Examples

### evaluate top-N list recommendations on a 0-1 data set
## Note: we sample only 100 users to make the example run faster
data("MSWeb")
MSWeb10 <- sample(MSWeb[rowCounts(MSWeb) >10,], 100)

## create an evaluation scheme (10-fold cross validation, given-3 scheme)
es <- evaluationScheme(MSWeb10, method="cross-validation",
        k=10, given=3)

## run evaluation
ev <- evaluate(es, "POPULAR", n=c(1,3,5,10))
ev

## look at the results (the length of the topNList is shown as column n)
getResults(ev)

## get a confusion matrices averaged over the 10 folds
avg(ev)
plot(ev, annotate = TRUE)

## evaluate several algorithms (including a hybrid recommender) with a list
algorithms <- list(
  RANDOM = list(name = "RANDOM", param = NULL),
  POPULAR = list(name = "POPULAR", param = NULL),
  HYBRID = list(name = "HYBRID", param =
      list(recommenders = list(
          RANDOM = list(name = "RANDOM", param = NULL),
          POPULAR = list(name = "POPULAR", param = NULL)
        )
      )
  )
)

evlist <- evaluate(es, algorithms, n=c(1,3,5,10))
evlist
names(evlist)

## select the first results by index
evlist[[1]]
avg(evlist[[1]])

plot(evlist, legend="topright")

### Evaluate using a data set with real-valued ratings
## Note: we sample only 100 users to make the example run faster
data("Jester5k")
es <- evaluationScheme(Jester5k[1:100], method="split",
  train=.9, given=10, goodRating=5)
## Note: goodRating is used to determine positive ratings

## predict top-N recommendation lists
## (results in TPR/FPR and precision/recall)
ev <- evaluate(es, "RANDOM", type="topNList", n=10)
getResults(ev)

## predict missing ratings
## (results in RMSE, MSE and MAE)
ev <- evaluate(es, "RANDOM", type="ratings")
getResults(ev)