quantile: Distribution Quantiles

In vincenzocoia/distionary: Create and Evaluate Probability Distributions

Distribution Quantiles

Description

Access a distribution's quantiles.

Usage

eval_quantile(distribution, at)

enframe_quantile(..., at, arg_name = ".arg", fn_prefix = "quantile", sep = "_")

Arguments

distribution, ...	A distribution, or possibly multiple distributions in the case of ....
at	Vector of values to evaluate the representation at.
arg_name	For enframe_, name of the column containing the function arguments. Length 1 character vector.
fn_prefix	For enframe_, name of the function to appear in the column(s). Length 1 character vector.
sep	When enframe'ing more than one distribution, the character that will be separating the fn_name and the distribution name. Length 1 character vector.

Details

When a quantile function does not exist, an algorithm is deployed that calculates the left inverse of the CDF. This algorithm works by progressively cutting the specified range in half, moving into the left or right half depending on where the solution is. The algorithm is not currently fast and is subject to improvement, and is a simple idea that has been passed around on the internet here and there. Tolerance is less than 1e-9, unless the maximum number of iterations (200) is reached.

Value

The evaluated representation in vector form (for eval_) with length matching the length of at, and data frame or tibble form (for enframe_) with number of rows matching the length of at. The at input occupies the first column, named .arg by default, or the specification in arg_name; the evaluated representations for each distribution in ... go in the subsequent columns (one column per distribution). For a single distribution, this column is named according to the representation by default (cdf, survival, quantile, etc.), or the value in fn_prefix. For multiple distributions, unnamed distributions are auto-named, and columns are named ⁠<fn_prefix><sep><distribution_name>⁠ (e.g., cdf_distribution1).

See Also

Other distributional representations: eval_cdf(), eval_chf(), eval_density(), eval_hazard(), eval_odds(), eval_pmf(), eval_return(), eval_survival()

Examples

d <- dst_unif(0, 4)
eval_quantile(d, at = 1:9 / 10)
enframe_quantile(d, at = 1:9 / 10)

vincenzocoia/distionary documentation built on Feb. 26, 2025, 11:09 a.m.