VB: Analysis: Von Bertalanffy

Description

The Von Bertalanffy model. It's a kind of growth curve for a time series and takes its name from its creator, Ludwig von Bertalanffy. It is a special case of the generalized logistic function. The growth curve (biology) is used to model the average length from age in animals.

Usage

VB(
  trat,
  resp,
  initial = NA,
  sample.curve = 1000,
  ylab = "Dependent",
  xlab = "Independent",
  theme = theme_classic(),
  legend.position = "top",
  r2 = "all",
  error = "SE",
  point = "all",
  width.bar = NA,
  scale = "none",
  textsize = 12,
  pointsize = 4.5,
  linesize = 0.8,
  linetype = 1,
  pointshape = 21,
  fillshape = "gray",
  colorline = "black",
  round = NA,
  yname.formula = "y",
  xname.formula = "x",
  comment = NA,
  fontfamily = "sans"
)

Value

The function returns a list containing the coefficients and their respective values of p; statistical parameters such as AIC, BIC, pseudo-R2, RMSE (root mean square error); largest and smallest estimated value and the graph using ggplot2 with the equation automatically.

Arguments

trat: Numeric vector with dependent variable.
resp: Numeric vector with independent variable.
initial: Starting estimates
sample.curve: Provide the number of observations to simulate curvature (default is 1000)
ylab: Variable response name (Accepts the expression() function)
xlab: Treatments name (Accepts the expression() function)
theme: ggplot2 theme (default is theme_bw())
legend.position: Legend position (default is "top")
r2: Coefficient of determination of the mean or all values (default is all)
error: Error bar (It can be SE - default, SD or FALSE)
point: Defines whether you want to plot all points ("all") or only the mean ("mean")
width.bar: Bar width
scale: Sets x scale (default is none, can be "log")
textsize: Font size
pointsize: Shape size
linesize: Line size
linetype: line type
pointshape: Format point (default is 21)
fillshape: Fill shape
colorline: Color lines
round: round equation
yname.formula: Name of y in the equation
xname.formula: Name of x in the equation
comment: Add text after equation
fontfamily: Font family

Author

Gabriel Danilo Shimizu

Leandro Simoes Azeredo Goncalves

Details

The model function for the von Bertalanffy model is: $$ y = L(1-exp(-k(t-t0)))$$

Examples

Run this code

library(AgroReg)
x=seq(1,20)
y=c(0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 0.91,
    0.92, 0.94, 0.96, 0.98, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00)
VB(x,y)

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