Calculate Peak Properties

step_measure_peaks_properties() creates a specification of a recipe step that calculates derived peak metrics from the measured signal and stores them in the .peaks tibble.

Usage

step_measure_peaks_properties(
  recipe,
  properties = c("prominence", "fwhm"),
  measures = NULL,
  role = NA,
  trained = FALSE,
  skip = FALSE,
  id = recipes::rand_id("measure_peaks_properties")
)

Arguments

recipe

A recipe object.

properties

Character vector of peak properties to calculate. Supported values are "prominence" and "fwhm".

measures

Optional character vector of measure column names.

role

Not used.

trained

Logical indicating if the step has been trained.

skip

Logical. Should the step be skipped when baking?

id

Unique step identifier.

Value

An updated recipe with the new step added.

Details

This step calculates additional peak metrics from the observed signal for each detected peak:

• "prominence": Peak height above the higher of the left and right base intensities.

• "fwhm": Full width at half maximum, estimated with linear interpolation after subtracting a local linear baseline between the left and right bases.

The calculated properties are added as new columns in the .peaks tibble and can be exported later with step_measure_peaks_to_table().

See also

Other peak-operations: step_measure_peaks_deconvolve(), step_measure_peaks_detect(), step_measure_peaks_filter(), step_measure_peaks_integrate(), step_measure_peaks_to_table()

Examples

library(recipes)

rec <- recipe(water + fat + protein ~ ., data = meats_long) |>
  update_role(id, new_role = "id") |>
  step_measure_input_long(transmittance, location = vars(channel)) |>
  step_measure_peaks_detect(min_height = 0.5) |>
  step_measure_peaks_properties(c("prominence", "fwhm")) |>
  prep()

result <- bake(rec, new_data = NULL)
result$.peaks[[1]]
#> # A tibble: 1 × 8
#>   peak_id location height left_base right_base  area prominence  fwhm
#>     <int>    <int>  <dbl>     <int>      <int> <dbl>      <dbl> <dbl>
#> 1       1       65   3.39         1        100    NA      0.576  35.8