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Add a section of a ROC curve to an existing one

add_partial_roc_curve.Rd

Add an specific region of a ROC curve to an existing ROC plot.

Usage

add_partial_roc_curve(
  data,
  response = NULL,
  predictor = NULL,
  ratio,
  threshold,
  .condition = NULL,
  .label = NULL
)

Arguments

data

A data.frame or extension (e.g. a tibble) containing values for predictors and response variables.

response

A data variable which must be a factor, integer or character vector representing the prediction outcome on each observation (Gold Standard).

If the variable presents more than two possible outcomes, classes or categories:

  • The outcome of interest (the one to be predicted) will remain distinct.

  • All other categories will be combined into a single category.

New combined category represents the "absence" of the condition to predict. See .condition for more information.

predictor

A data variable which must be numeric, representing values of a classifier or predictor for each observation.

ratio

Ratio or axis where to apply calculations.

  • If "tpr", only points within the specified region of TPR, y axis, will be considered for calculations.

  • If "fpr", only points within the specified region of FPR, x axis, will be considered for calculations.

threshold

A number between 0 and 1, both inclusive, which represents the region bound where to calculate partial area under curve.

If ratio = "tpr", it represents lower bound of the TPR region, being its upper limit equal to 1.

If ratio = "fpr", it represents the upper bound of the FPR region, being its lower limit equal to 0.

.condition

A value from response that represents class, category or condition of interest which wants to be predicted.

If NULL, condition of interest will be selected automatically depending on response type.

Once the class of interest is selected, rest of them will be collapsed in a common category, representing the "absence" of the condition to be predicted.

See vignette("selecting-condition") for further information on how automatic selection is performed and details on selecting the condition of interest.

.label

A string representing the name used in labels.

If NULL, variable name from predictor will be used as label.

Examples

plot_roc_curve(iris, response = Species, predictor = Sepal.Width) +
  add_partial_roc_curve(
    iris,
    response = Species,
    predictor = Sepal.Length,
    ratio = "tpr",
    threshold = 0.9
  )