ciu {ciu}

Create ciu object.

Description

Sets up a ciu object with the given parameters. This is not the same as a CIU object as returned by the function ciu.new! a ciu object is a list with all the parameter values needed for Contextual Importance and Utility calculations, whereas a CIU object only exposes a set of methods that can be called using the $ operator. CIU provides the method ⁠$as.ciu⁠ for retrieving a ciu object from a CIU object.

Usage

ciu(
  model,
  formula = NULL,
  data = NULL,
  in.min.max.limits = NULL,
  abs.min.max = NULL,
  input.names = NULL,
  output.names = NULL,
  predict.function = NULL,
  vocabulary = NULL
)

Arguments

model

Model/"black-box" object (same parameter as bb for function ciu.new).

formula

Formula that describes input versus output values. Only to be used together with data parameter.

data

The training data used for training the model. If this parameter is provided, a formula MUST be given also. ciu.new attempts to infer the other parameters from data and formula. i.e. in.min.max.limits, abs.min.max, input.names and output.names. If those parameters are provided, then they override the inferred ones.

in.min.max.limits

matrix with one row per output and two columns, where the first column indicates the minimal value and the second column the maximal value for that input.

abs.min.max

data.frame or matrix of min-max values of outputs, one row per output, two columns (min, max).

input.names

labels of inputs.

output.names

labels of outputs.

predict.function

can be supplied if a model that is not supported by ciu should be used. As an example, this is the function for lda:

o.predict.function <- function(model, inputs) {
    pred <- predict(model,inputs)
        return(pred$posterior)
}

vocabulary

list of labels/concepts to be used when producing explanations and what combination of inputs they correspond to. Example of two intermediate concepts and a higher-level one that combines them: list(intermediate.concept1=c(1,2,3), intermediate.concept2=c(4,5), higher.level.concept=c(1,2,3,4,5))

Value

ciu object.

Author(s)

Kary Främling

See Also

ciu.new

Examples

# Explaining the classification of an Iris instance with lda model.
# We use a versicolor (instance 100).
library(MASS)
test.ind <- 100
iris_test <- iris[test.ind, 1:4]
iris_train <- iris[-test.ind, 1:4]
iris_lab <- iris[[5]][-test.ind]
model <- lda(iris_train, iris_lab)

# Create CIU object
ciu <- ciu(model, Species~., iris)

# This can be used with explain method for getting CIU values
# of one or several inputs. Here we get CIU for all three outputs
# with input feature "Petal.Length" that happens to be the most important.
ciu.explain(ciu, iris_test, 1)

# It is, however, more convenient to use one of the graphical visualizations.
# Here's one using ggplot.
ciu.ggplot.col(ciu, iris_test)