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lmomco (version 1.3.3)

pp: Plotting-Position Formula

Description

The plotting positions of a data vector (x) are returned in ascending order. The plotting-position formula is

$$pp_i = \frac{i-a}{n+1-2a} \mbox{,}$$

where $pp_i$ is the nonexceedance probability $F$ of the $i$th ascending data value. The parameter $a$ specifies the plotting-position type, and $n$ is the sample size (length(x)).

Usage

pp(x, a=0, sort=TRUE)

Arguments

x
A vector of data values. The vector is used to get sample size through length();
a
A value for the plotting-position formula, default is A=0, which returns the Weibull plotting positions; and
sort
A logical whether the ranks of the data are sorted prior to $F$ computation.

Value

  • An R vector is returned.

References

Stedinger, J.R., Vogel, R.M., and Foufoula-Georgiou, E., 1992, Frequency analysis of extreme events, in Handbook of Hydrology, chapter 18, editor-in-chief D. A. Maidment: McGraw-Hill, New York.

See Also

nonexceeds, pwm.pp

Examples

Run this code
Q <- rnorm(20)
PP <- pp(Q)
plot(PP,sort(Q))

Q <- rweibull(30,1.4,scale=400)
WEI <- parwei(lmom.ub(Q))
PP <- pp(Q)
plot(PP,sort(Q))
lines(PP,quawei(PP,WEI))

# This plot looks similar, but when connecting lines are added
# the nature of the sorting is obvious.
plot(pp(Q,sort=FALSE), Q)
lines(pp(Q,sort=FALSE), Q, col=2)

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