quantile_pts: Quantile-based cut points for coplots

In ggRandomForests: Visually Exploring Random Forests

Quantile-based cut points for coplots

Description

This helper wraps quantile to create well-spaced cut points for conditioning plots. When intervals = TRUE the lower boundary is nudged down so that cut() treats the minimum value as a valid observation.

The output can be passed directly into the breaks argument of the cut function for creating groups for coplots.

Usage

quantile_pts(object, groups, intervals = FALSE)

Arguments

object	Numeric vector of predictor values.
groups	Number of quantile points (or intervals) to compute.
intervals	Logical indicating whether to return interval boundaries suitable for cut() (length groups + 1) or the interior quantile points (length groups).

Value

Numeric vector of quantile points. When intervals = TRUE the result is strictly increasing and can be supplied to cut() to produce groups balanced strata.

See Also

cut

Examples

if (requireNamespace("MASS", quietly = TRUE)) {
  data(Boston, package = "MASS")
  rfsrc_boston <- randomForestSRC::rfsrc(medv ~ ., Boston)

  # To create 6 intervals, we want 7 points.
  # quantile_pts will find balanced intervals
  rm_pts <- quantile_pts(rfsrc_boston$xvar$rm, groups = 6, intervals = TRUE)

  # Use cut to create the intervals
  rm_grp <- cut(rfsrc_boston$xvar$rm, breaks = rm_pts)

  summary(rm_grp)
}

ggRandomForests documentation built on Aug. 4, 2026, 5:09 p.m.