rgr (version 1.0.4)

cnpplt: Cumulative Normal Percentage Probability (CPP) Plot

Description

Displays a cumulative normal percentage probability (CPP) plot, equivalent to a Q-Q plot, as has been traditionally used by physical scientists and engineers.

Usage

cnpplt(xx, xlab = deparse(substitute(xx)), 
	ylab = "% Cumulative Probability", log = FALSE, xlim = NULL, 
	main = " ", pch = 3, cex.axis = 1, ifqs = FALSE, ifshape = FALSE)

Arguments

xx

name of the variable to be plotted.

xlab

a title for the x-axis. It is often desirable to replace the default x-axis title of the input variable text string with a more informative title, e.g., xlab ="Cu (mg/kg) in <2 mm="" o-horizon="" soil"<="" code="">.

ylab

a title for the y-axis, defaults to "% Cumulative Probability".

log

if it is required to display the data with logarithmic (x-axis) scaling, set log = TRUE.

xlim

when used in the shape function, xlim is determined by function gx.hist and used to ensure all four panels in

main

when used stand-alone a title may be added optionally above the plot by setting main, e.g., main = "Kola Project, 1995".

pch

by default the plotting symbol is set to a plus, pch = 3, alternate plotting symbols may be chosen from those displayed by display.marks.

cex.axis

if overplotting occurs in the y-axis labelling the size of the y-axis labels may be reduced by setting cex.axis to a number smaller than 1, e.g., 0.8.

ifqs

setting ifqs = TRUE results in horizontal and vertical dotted lines being plotted at the three central quartiles and their values, respectively.

ifshape

when used with function shape or caplot to plot into a panel set ifshape = TRUE to ensure only essential probability scale axis labels are displaye

See Also

display.marks, ltdl.fix.df, remove.na

Examples

## Make test data available
data(kola.o)
attach(kola.o)

## A stand-alone cumulative normal percentage probability plot
cnpplt(Cu)

## A more appropriately labelled and scaled cumulative normal percentage
## probability plot using a cross/x rather than a plus
cnpplt(Cu, xlab = "Cu (mg/kg) in <2 mm O-horizon soil", log = TRUE, 
	pch = 4)

## Detach test data
detach(kola.o)