Package 'kumquat'

Complex Boundary Example Dataset

Description

A demonstration dataset containing two numeric predictors and a binary class variable. The class boundary is set to A when x < (-0.5) & y < (-0.3) or when x >= -0.5 & x < 0.4 & y < 0.1 + 0.8 * x or when x >= 0.4 and B elsewhere

Usage

data(d_multi)

Format

A tibble with 5,000 rows and 3 variables:

x

Numeric independent variable generated from a uniform distribution on [-1, 1]

y

Numeric independent variable generated from a uniform distribution on [-1, 1]

class

Binary categorical variable with two levels: "A" and "B"

Details

Simple two-dimensional dataset with a complex decison boundary.

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Combined Boundary Example Dataset

Description

A demonstration dataset containing two numeric predictors and a binary class variable. The class boundary is set to A when x < (-0.5) & y < (-0.3) or when x >= -0.5 & x < 0.4 & y < 0.1 + 0.8 * x or when x >= 0.4 B when y < (-1) + 0.8 * x and everywhere else

Usage

data(d_multitwo)

Format

A tibble with 5,000 rows and 3 variables:

x

Numeric independent variable generated from a uniform distribution on [-1, 1]

y

Numeric independent variable generated from a uniform distribution on [-1, 1]

class

Binary categorical variable with two levels: "A" and "B"

Details

Simple two-dimensional dataset with a combination of two decision boundaries

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Oblique Boundary Example Dataset

Description

A demonstration dataset containing two numeric predictors and a binary class variable. The class boundary is defined based on the inequality: y > 0.1 + 1.4 * x

Usage

data(d_oblique)

Format

A tibble with 5,000 rows and 3 variables:

x

Numeric independent variable generated from a uniform distribution on [-1, 1]

y

Numeric independent variable generated from a uniform distribution on [-1, 1]

class

Binary categorical variable with two levels: "A" and "B"

Details

Simple two-dimensional dataset with an oblique decision boundary.

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Vertical Boundary Example Dataset

Description

A demonstration dataset containing two numeric predictors and a binary class variable. The class boundary is defined by a vertical split at x = 0.3.

Usage

data(d_vertical)

Format

A tibble with 5,000 rows and 3 variables:

x

Numeric independent variable generated from a uniform distribution on [-1, 1]

y

Numeric independent variable generated from a uniform distribution on [-1, 1]

class

Binary categorical variable with two levels: "A" and "B"

Details

Simple two-dimensional dataset with a vertical decision boundary.

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Fit Local Linear Model and Compute Feature Importance

Description

Fit Local Linear Model and Compute Feature Importance

Usage

fit_local_model(
  perturbations,
  predictor_vars,
  nfolds = 50,
  alpha = 1,
  class_names = c("A", "B")
)

Arguments

perturbations	Data frame of perturbations with predictions
predictor_vars	Character vector of predictor variable names
nfolds	Number of folds for cross-validation (default: 50)
alpha	Elastic net mixing parameter (default: 1 for lasso)
class_names	Character vector of class names for binary classification

Value

A list containing glm_predictions, importances, and the fitted model

Examples

perturbations <- data.frame(
   x1 = c(1, 2, 3),
   x2 = c(4, 5, 6),
   pred = c("A", "A", "A")
 )

 result <- fit_local_model(
   perturbations,
   predictor_vars = c("x1", "x2")
 )

---

Generate Perturbations Around a Point of Interest

Description

Generate Perturbations Around a Point of Interest

Usage

generate_perturbations(
  data,
  poi,
  radius = 0.1,
  step = 0.01,
  predictors = names(data)
)

Arguments

data	Training data frame
poi	Row number of point of interest
radius	Perturbation radius (default: 0.1)
step	Step size for perturbations (default: 0.01)
predictors	Character vector of predictor variable names

Value

A data frame of perturbed points. The output contains the following properties:

• Columns are predictors

• Number of rows are going to be dependent on radius and step

Examples

data <- data.frame(
  x = 1,
  y = 2
)
result <- generate_perturbations(
  data,
  poi = 1,
  radius = 0.1,
  step = 0.1,
  predictors = c("x", "y")
 )

---

Complete Local Interpretation Pipeline

Description

Complete Local Interpretation Pipeline

Usage

kumquat(
  model_bundle,
  data,
  pois,
  perturbations = NULL,
  radius = 0.1,
  step = 0.01,
  predictor_vars = c("x", "y"),
  nfolds = 50,
  alpha = 1,
  class_names = c("A", "B"),
  predict_func = stats::predict
)

Arguments

model_bundle	A trained model held in a bundle::bundle()
data	Training data
pois	Points of interest (row numbers)
perturbations	A data.frame of perturbations to be used to fit the local model
radius	Perturbation radius (default: 0.1)
step	Perturbation step size (default: 0.01)
predictor_vars	Character vector of predictor variable names
nfolds	Number of CV folds (default: 50)
alpha	Elastic net parameter (default: 1)
class_names	Character vector of class names
predict_func	A function that takes in two arguments: model and data and returns a vector of factors

Value

A list containing perturbations, predictions, and local model results

Examples

data(d_vertical)
rfmodel <- randomForest::randomForest(
 class ~ x + y,
 data = d_vertical
)
# Bundle model up
rfmodel_bundled <- bundle::bundle(rfmodel)
ks <- kumquat(
 rfmodel_bundled,
 d_vertical,
  1,
  class_names = unique(d_vertical$class)
)

---

Extract and Combine Feature Importances from Kumquat Objects

Description

pinch_importance() extracts feature importance values from kumquats and combines them into a single data frame.

Usage

pinch_importance(kumquats)

Arguments

kumquats

A result from a call to make_kumquats

Value

A data.frame where each row corresponds to the feature importances extracted from one kumquat object. Column names represent feature names.

Examples

data(d_vertical)
rfmodel <- randomForest::randomForest(
 class ~ x + y,
 data = d_vertical
)
# Bundle model up
rfmodel_bundled <- bundle::bundle(rfmodel)
ks <- kumquat(
 rfmodel_bundled,
 d_vertical,
  1,
  class_names = unique(d_vertical$class)
)
imps <- pinch_importance(ks)

---

Plot point of interest with perturbations and predictions

Description

This function generates a ggplot visualizing the perturbations of a local model, overlaying the training data and highlighting a specific point of interest (poi). The plot subtitle shows the importances of the first two features.

Usage

plot_interest(kquat)

Arguments

kquat

A list-like object containing at least: local_model$importances numeric vector local_model$glm_predictions numeric vector perturbations data.frame with columns x and y train_data data.frame with columns x, y, and class poi integer or index of the point of interest

Value

A ggplot object

Examples

data(d_vertical)
rfmodel <- randomForest::randomForest(
 class ~ x + y,
 data = d_vertical
)
# Bundle model up
rfmodel_bundled <- bundle::bundle(rfmodel)
ks <- kumquat(
 rfmodel_bundled,
 d_vertical,
  1,
  class_names = unique(d_vertical$class)
)
plot_obj <- plot_interest(ks)

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