agespectrum  R Documentation 
Produces a plot of boxes whose widths correspond to the cumulative
amount of ^{39}
Ar (or any other variable), and whose heights
express the analytical uncertainties. Only propagates the
analytical uncertainty associated with decay constants and
Jfactors after computing the plateau composition.
agespectrum(x, ...)
## Default S3 method:
agespectrum(
x,
oerr = 3,
plateau = TRUE,
random.effects = FALSE,
levels = NA,
clabel = "",
plateau.col = c("#00FF0080", "#FF000080"),
non.plateau.col = "#00FFFF80",
sigdig = 2,
line.col = "red",
lwd = 2,
xlab = "cumulative fraction",
ylab = "X",
hide = NULL,
omit = NULL,
...
)
## S3 method for class 'other'
agespectrum(
x,
oerr = 3,
plateau = TRUE,
random.effects = FALSE,
levels = NA,
clabel = "",
plateau.col = c("#00FF0080", "#FF000080"),
non.plateau.col = "#00FFFF80",
sigdig = 2,
line.col = "red",
lwd = 2,
xlab = "cumulative fraction",
ylab = "X",
hide = NULL,
omit = NULL,
...
)
## S3 method for class 'ArAr'
agespectrum(
x,
oerr = 3,
plateau = TRUE,
random.effects = FALSE,
levels = NA,
clabel = "",
plateau.col = c("#00FF0080", "#FF000080"),
non.plateau.col = "#00FFFF80",
sigdig = 2,
exterr = FALSE,
line.col = "red",
lwd = 2,
i2i = FALSE,
hide = NULL,
omit = NULL,
...
)
x 
a threecolumn matrix whose first column gives the amount of
OR an object of class 
... 
optional parameters to the generic 
oerr 
indicates whether the analytical uncertainties of the output are reported in the plot title as:

plateau 
logical flag indicating whether a plateau age should
be calculated. If 
random.effects 
if if 
levels 
a vector with additional values to be displayed as different background colours of the plot symbols. 
clabel 
label of the colour legend 
plateau.col 
Fill colours of the rectangles used to mark the steps belonging to
the age plateau. This can either be a single colour or multiple
colours to form a colour ramp (to be used if a single colour: multiple colours: a colour palette: a reversed palette: For empty boxes, set 
non.plateau.col 
if 
sigdig 
the number of significant digits of the numerical values reported in the title of the graphical output. 
line.col 
colour of the average age line 
lwd 
width of the average age line 
xlab 
xaxis label 
ylab 
yaxis label 
hide 
vector with indices of aliquots that should be removed from the plot. 
omit 
vector with indices of aliquots that should be plotted but omitted from age plateau calculation 
exterr 
propagate the external (decay constant and calibration factor) uncertainties? 
i2i 
‘isochron to intercept’: calculates the initial (aka
‘inherited’, ‘excess’, or ‘common’) 
IsoplotR
defines the ‘plateau age’ as the weighted mean age
(using a random effects model with two sources of dispersion) of
the longest sequence (in terms of cumulative ^{39}
Ar content)
of consecutive heating steps that pass the modified Chauvenet
criterion (see weightedmean
). Note that this
definition is different (and simpler) than the one used by
Isoplot
(Ludwig, 2003). However, it is important to mention
that all definitions of an age plateau are heuristic by nature and
should not be used for quantitative inference. It is possible (and
likely) that the plateau steps exhibit significant
overdispersion. This overdispersion can be manually reduced by
removing individual heating steps with the optional omit
argument.
If plateau=TRUE
, returns a list containing the output of the
weightedmean
function, plus the following items:
the fraction of ^{39}
Ar contained in the
plateau
indices of the steps that are retained for the plateau age calculation
weightedmean
attach(examples)
par(mfrow=c(2,1))
agespectrum(ArAr)
# removing the first 6 steps yields the longest plateau
# that passes the chisquare test for homogeneity
agespectrum(ArAr,omit=1:6)
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