ggspectra (version 0.3.1)

stat_peaks: Find peaks and valleys.

Description

stat_peaks finds at which x positions local maxima are located. If you want find local minima, you can use stat_valleys instead.

Usage

stat_peaks(mapping = NULL, data = NULL, geom = "point", span = 5,
  ignore_threshold = 0.01, strict = FALSE, label.fmt = "%.3g",
  x.label.fmt = label.fmt, y.label.fmt = label.fmt,
  position = "identity", na.rm = FALSE, show.legend = FALSE,
  inherit.aes = TRUE, ...)
stat_valleys(mapping = NULL, data = NULL, geom = "point", span = 5,
  ignore_threshold = -0.01, strict = FALSE, label.fmt = "%.3g",
  x.label.fmt = label.fmt, y.label.fmt = label.fmt,
  position = "identity", na.rm = FALSE, show.legend = FALSE,
  inherit.aes = TRUE, ...)

Arguments

mapping

The aesthetic mapping, usually constructed with aes or aes_. Only needs to be set at the layer level if you are overriding the plot defaults.

data

A layer specific dataset - only needed if you want to override the plot defaults.

geom

The geometric object to use display the data

span

a peak is defined as an element in a sequence which is greater than all other elements within a window of width span centered at that element. The default value is 5, meaning that a peak is bigger than two consequtive neighbors on each side. Default: 5.

ignore_threshold

numeric value between 0.0 and 1.0 indicating the size threshold below which peaks will be ignored.

strict

logical flag: if TRUE, an element must be strictly greater than all other values in its window to be considered a peak. Default: FALSE.

label.fmt

character string giving a format definition for converting values into character strings by means of function sprintf.

x.label.fmt

character string giving a format definition for converting $x$-values into character strings by means of function sprintf.

y.label.fmt

character string giving a format definition for converting $y$-values into character strings by means of function sprintf.

position

The position adjustment to use for overlapping points on this layer

na.rm

a logical value indicating whether NA values should be stripped before the computation proceeds.

show.legend

logical. Should this layer be included in the legends? NA, the default, includes if any aesthetics are mapped. FALSE never includes, and TRUE always includes.

inherit.aes

If FALSE, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g. borders.

...

other arguments passed on to layer. This can include aesthetics whose values you want to set, not map. See layer for more details.

Value

A data frame with one row for each peak (or valley) found in the data.

Computed variables

x

x-value at the peak (or valley) as numeric

y

y-value at the peak (or valley) as numeric

x.label

x-value at the peak (or valley) formatted as character

y.label

y-value at the peak (or valley) formatted as character

wl.color

color definition calculated by assuming that x-values are wavelengths expressed in nanometres.

Default aesthetics

Set by the statistic and available to geoms.

label

..x.label..

xintercept

..x..

yintercept

..y..

fill

..wl.color..

Required aesthetics

Required by the statistic and need to be set with aes().

x

numeric, wavelength in nanometres

y

numeric, a spectral quantity

Details

These stats use geom_point by default as it is the geom most likely to work well in almost any situation without need of tweaking. The default aesthetics set by these stats allow their direct use with geom_text, geom_label, geom_line, geom_rug, geom_hline and geom_vline. The formatting of the labels returned can be controlled by the user.

See Also

find_peaks, which is used internally.

Other stats functions: stat_color, stat_find_qtys, stat_find_wls, stat_label_peaks, stat_wb_box, stat_wb_column, stat_wb_contribution, stat_wb_hbar, stat_wb_irrad, stat_wb_label, stat_wb_mean, stat_wb_relative, stat_wb_sirrad, stat_wb_total, stat_wl_strip, stat_wl_summary

Examples

# NOT RUN {
library(photobiology)
library(ggplot2)
# ggplot() methods for spectral objects set a default mapping for x and y.
ggplot(sun.spct) + geom_line() + stat_peaks()
ggplot(sun.spct) + geom_line() + stat_valleys()
ggplot(sun.spct) + geom_line() +
  stat_peaks(span = 21, geom = "point", colour = "red") +
  stat_peaks(span = 51, geom = "text", colour = "red",
             vjust = -0.3, label.fmt = "%3.0f nm")
ggplot(sun.spct, unit.out = "photon") + geom_point() +
  stat_peaks(span = 5, geom = "line", colour = "red")
# }