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IsoplotR (version 1.0)

radialplot: Visualise heteroscedastic data on a radial plot

Description

Implementation of a graphical device developed by Rex Galbraith to display several estimates of the same quantity that have different standard errors.

Usage

radialplot(x, ...)

# S3 method for default radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", sigdig = 2, show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), title = TRUE, k = 0, markers = NULL, alpha = 0.05, ...)

# S3 method for fissiontracks radialplot(x, from = NA, to = NA, t0 = NA, transformation = "arcsin", sigdig = 2, show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), title = TRUE, markers = NULL, k = 0, exterr = TRUE, alpha = 0.05, ...)

# S3 method for UPb radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", type = 4, cutoff.76 = 1100, cutoff.disc = c(-15, 5), show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, exterr = TRUE, common.Pb = 0, alpha = 0.05, ...)

# S3 method for PbPb radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, exterr = TRUE, common.Pb = 1, alpha = 0.05, ...)

# S3 method for ArAr radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, exterr = TRUE, i2i = FALSE, alpha = 0.05, ...)

# S3 method for UThHe radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, alpha = 0.05, ...)

# S3 method for ReOs radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, exterr = TRUE, i2i = TRUE, alpha = 0.05, ...)

# S3 method for SmNd radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, exterr = TRUE, i2i = TRUE, alpha = 0.05, ...)

# S3 method for RbSr radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, exterr = TRUE, i2i = TRUE, alpha = 0.05, ...)

# S3 method for LuHf radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, exterr = TRUE, i2i = TRUE, alpha = 0.05, ...)

# S3 method for ThU radialplot(x, from = NA, to = NA, t0 = NA, transformation = "log", show.numbers = FALSE, pch = 21, levels = NA, clabel = "", bg = c("white", "red"), markers = NULL, k = 0, i2i = TRUE, alpha = 0.05, ...)

Arguments

x

Either an [n x 2] matix of (transformed) values z and their standard errors s

OR

and object of class fissiontracks, UThHe, ArAr, ReOs, SmNd, RbSr, LuHf, ThU, PbPb or UPb

...

additional arguments to the generic points function

from

minimum age limit of the radial scale

to

maximum age limit of the radial scale

t0

central value

transformation

one of either log, linear or (if x has class fissiontracks), arcsin.

sigdig

the number of significant digits of the numerical values reported in the title of the graphical output.

show.numbers

boolean flag (TRUE to show grain numbers)

pch

plot character (default is a filled circle)

levels

a vector with additional values to be displayed as different background colours of the plot symbols.

clabel

label of the colour legend

bg

a vector of two background colours for the plot symbols. If levels=NA, then only the first colour is used. If levels is a vector of numbers, then bg is used to construct a colour ramp.

title

add a title to the plot?

k

number of peaks to fit using the finite mixture models of Galbraith and Laslett (1993). Setting k='auto' automatically selects an optimal number of components based on the Bayes Information Criterion (BIC). Setting k='min' estimates the minimum value using a three parameter model consisting of a Normal distribution truncated by a discrete component.

markers

vector of ages of radial marker lines to add to the plot.

alpha

cutoff value for confidence intervals

exterr

propagate the external sources of uncertainty into the mixture model errors?

type

scalar indicating whether to plot the \(^{207}\)Pb/\(^{235}\)U age (type=1), the \(^{206}\)Pb/\(^{238}\)U age (type=2), the \(^{207}\)Pb/\(^{206}\)Pb age (type=3), the \(^{207}\)Pb/\(^{206}\)Pb-\(^{206}\)Pb/\(^{238}\)U age (type=4), or the (Wetherill) concordia age (type=5)

cutoff.76

the age (in Ma) below which the \(^{206}\)Pb/\(^{238}\)U and above which the \(^{207}\)Pb/\(^{206}\)Pb age is used. This parameter is only used if type=4.

cutoff.disc

two element vector with the maximum and minimum percentage discordance allowed between the \(^{207}\)Pb/\(^{235}\)U and \(^{206}\)Pb/\(^{238}\)U age (if \(^{206}\)Pb/\(^{238}\)U < cutoff.76) or between the \(^{206}\)Pb/\(^{238}\)U and \(^{207}\)Pb/\(^{206}\)Pb age (if \(^{206}\)Pb/\(^{238}\)U > cutoff.76). Set cutoff.disc=NA if you do not want to use this filter.

common.Pb

apply a common lead correction using one of three methods:

1: use the isochron intercept as the initial Pb-composition

2: use the Stacey-Kramer two-stage model to infer the initial Pb-composition

3: use the Pb-composition stored in settings('iratio','Pb206Pb204') and settings('iratio','Pb207Pb204')

i2i

`isochron to intercept': calculates the initial (aka `inherited', `excess', or `common') \(^{40}\)Ar/\(^{36}\)Ar, \(^{207}\)Pb/\(^{204}\)Pb, \(^{87}\)Sr/\(^{86}\)Sr, \(^{143}\)Nd/\(^{144}\)Nd, \(^{187}\)Os/\(^{188}\)Os or \(^{176}\)Hf/\(^{177}\)Hf ratio from an isochron fit. Setting i2i to FALSE uses the default values stored in settings('iratio',...). When applied to data of class ThU, setting i2i to TRUE applies a detrital Th-correction.

Details

The radial plot (Galbraith, 1988, 1990) is a graphical device that was specifically designed to display heteroscedastic data, and is constructed as follows. Consider a set of dates \(\{t_1,...,t_i,...,t_n\}\) and uncertainties \(\{s[t_1],...,s[t_i],...,s[t_n]\}\). Define \(z_i = z[t_i]\) to be a transformation of \(t_i\) (e.g., \(z_i = log[t_i]\)), and let \(s[z_i]\) be its propagated analytical uncertainty (i.e., \(s[z_i] = s[t_i]/t_i\) in the case of a logarithmic transformation). Create a scatterplot of \((x_i,y_i)\) values, where \(x_i = 1/s[z_i]\) and \(y_i = (z_i-z_\circ)/s[z_i]\), where \(z_\circ\) is some reference value such as the mean. The slope of a line connecting the origin of this scatterplot with any of the \((x_i,y_i)\)s is proportional to \(z_i\) and, hence, the date \(t_i\). These dates can be more easily visualised by drawing a radial scale at some convenient distance from the origin and annotating it with labelled ticks at the appropriate angles. While the angular position of each data point represents the date, its horizontal distance from the origin is proportional to the precision. Imprecise measurements plot on the left hand side of the radial plot, whereas precise age determinations are found further towards the right. Thus, radial plots allow the observer to assess both the magnitude and the precision of quantitative data in one glance.

References

Galbraith, R.F., 1988. Graphical display of estimates having differing standard errors. Technometrics, 30(3), pp.271-281.

Galbraith, R.F., 1990. The radial plot: graphical assessment of spread in ages. International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 17(3), pp.207-214.

Galbraith, R.F. and Laslett, G.M., 1993. Statistical models for mixed fission track ages. Nuclear Tracks and Radiation Measurements, 21(4), pp.459-470.

See Also

peakfit, central

Examples

Run this code
# NOT RUN {
data(examples)
radialplot(examples$FT1)

dev.new()
radialplot(examples$LudwigMixture,k='min')

# }

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