stat_find_qtys
finds at which y positions values equal to an x target
are located. Axis flipping is currently not supported.
Usage
stat_find_qtys(
mapping = NULL,
data = NULL,
geom = "point",
position = "identity",
...,
target = "half.maximum",
interpolate = TRUE,
chroma.type = "CMF",
label.fmt = "%.3g",
x.label.fmt = label.fmt,
y.label.fmt = label.fmt,
x.label.transform = I,
y.label.transform = I,
x.colour.transform = x.label.transform,
na.rm = FALSE,
show.legend = FALSE,
inherit.aes = TRUE
)
Arguments
- mapping
The aesthetic mapping, usually constructed with
aes
oraes_
. 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
- position
The position adjustment to use for overlapping points on this layer
- ...
other arguments passed on to
layer
. This can include aesthetics whose values you want to set, not map. Seelayer
for more details.- target
numeric value indicating the spectral quantity value for which wavelengths are to be searched and interpolated if need. The character string "half.maximum" is also accepted as argument.
- interpolate
logical Indicating whether the nearest wavelength value in
x
should be returned or a value calculated by linear interpolation between wavelength values straddling the target.- chroma.type
character one of "CMF" (color matching function) or "CC" (color coordinates) or a
chroma_spct
object.- label.fmt, x.label.fmt, y.label.fmt
character strings giving a format definition for construction of character strings labels with function
sprintf
fromx
and/ory
values.- x.label.transform, y.label.transform, x.colour.transform
function Applied to
x
ory
values when constructing the character labels or computing matching colours.- 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, andTRUE
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
.
Value
A data frame with one row for each match to the target subset from
the data or linearly interpolated between the two nearest values available.
As spectra are monotonic in wavelength, this statistic will never return
more than one row in data
per target value.
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.
Note
These stats work nicely together with geoms geom_text_repel
and
geom_label_repel
from package ggrepel
to
solve the problem of overlapping labels by displacing them. To discard
overlapping labels use check_overlap = TRUE
as argument to
geom_text
. By default the labels are character values suitable to be
plotted as is, but with a suitable label.fmt
labels suitable for
parsing by the geoms (e.g. into expressions containing greek letters or
super or subscripts) can be also easily obtained.
Computed variables
- x
x-value at or nearest to the match to the target as numeric
- y
target value or y-value nearest to the target as numeric
- x.label
x-value at or nearest to the match formatted as character
- y.label
target value or y-value nearest to the target formatted as character
- 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
..color..
Required aesthetics
Required by the statistic and need to be set
with aes()
.
- x
numeric, wavelength in nanometres
- y
numeric, a spectral quantity
See also
Other stats functions:
stat_color()
,
stat_find_wls()
,
stat_label_peaks()
,
stat_peaks()
,
stat_spikes()
,
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
# ggplot() methods for spectral objects set a default mapping for x and y.
ggplot(yellow_gel.spct) +
geom_line() +
stat_find_qtys(target = "half.range")
ggplot(yellow_gel.spct) +
geom_line() +
stat_find_qtys(target = c(490, 500, 510))
ggplot(yellow_gel.spct) +
geom_line() +
stat_find_qtys(target = 500, geom = "point", colour = "red") +
stat_find_qtys(target = 500, geom = "text", colour = "red",
hjust = 1.1, label.fmt = "Tfr = %1.2f")