zhuang4: R optimization of a four-parameter van Genuchten particle...

Description Usage Arguments Value Author(s) References See Also Examples

Description

The function optimises 4-parameter van Genuchten particle size distribution function of Zhuang et al(2001).

Usage

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zhuang4(data = NULL, D = NULL, fr = NULL, p = NULL, group = NULL,
  a = 1, b = 1, e = 1e-05, z = 1)

## Default S3 method:
zhuang4(data = NULL, D = NULL, fr = NULL, p = NULL,
  group = NULL, a = 1, b = 1, e = 1e-05, z = 1)

## S3 method for class 'zhuang4'
plot(x, main = "Particle Size Distribution Function",
  xlab = "Particle Diameter", ylab = "Fraction", ...)

## S3 method for class 'zhuang4'
coef(object, ...)

## S3 method for class 'zhuang4'
predict(object, D, ...)

Arguments

data

a dataframe of Particle Size Distribution. It can have column names of diameter of the particles "D" [mm], and fraction of the particles "fr" that ranges from 0-1.

D

character. The corresponding diameter in the data.

fr

character. The corresponding fraction of the particles.

p

porosity[g/m^3]

group

character. The name of the group variables if the data is from different areas.

a

an initial value of 'a' parameter to be optimised

b

an initial value of 'b' parameter to be optimised

e

an initial value of 'e' parameter to be optimised

z

an initial value of 'z' parameter to be optimised

x

a return object of the function.

main

Title of the plot

xlab

x label of the plot

ylab

y label of the plot

...

Any other graphical parameter

object

Model output object

Value

Author(s)

George Owusu

References

Zhuang, J., Jin, Y., & Miyazaki, T. (2001). Estimating water retention characteristic from soil particle-size distribution using a non-similar media concept. Soil Sci., 166, 308-321.

See Also

zhuang3, haverkamp,lass3,logarithmic, logistic2, logistic3,logistic4,fredlund3, fredlund4, jaky,andersson,gompertz

Other van-Genuchten functions: haverkamp, zhuang3

Examples

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data=read.csv(system.file("ext","sys","soil2.csv",package="vadose"))
single<- subset(data, ID=="30B20_1")
mod=zhuang4 (data=single,p="sand",D="D",fr="Sand.")
plot(mod)
## Not run: 
#group simulation
mod2=zhuang4 (data=data,D="D",fr="FractionSand",group="ID")
mod2$coef

## End(Not run)

gowusu/vadose documentation built on May 17, 2019, 7:59 a.m.