walfordChapmanPlot: Constructs Ford-Walford and Chapman plots for mean...

In droglenc/FSAmisc: Miscellaneous functions for simple fisheries stock assessment methods

Constructs Ford-Walford and Chapman plots for mean length-at-age data.

Description

Constructs Ford-Walford and Chapman plots for mean length-at-age data and computes estimates of asymptotic mean length (Linf) and the Brody growth coefficient (K).

Usage

walfordPlot(
  formula,
  data = NULL,
  xlab = expression(L[t]),
  ylab = expression(L[t + 1]),
  colLS = "blue",
  colRL = "red",
  lwdLS = 2,
  lwdRL = 2,
  ltyLS = 1,
  ltyRL = 2,
  pch = 19,
  col = "black",
  pchLinf = 9,
  colLinf = "red",
  cexLinf = 1.5,
  showLS = TRUE,
  showVB = TRUE,
  ...
)

chapmanPlot(
  formula,
  data = NULL,
  xlab = expression(L[t]),
  ylab = expression(L[t + 1] - L[t]),
  colLS = "blue",
  ltyLS = 1,
  lwdLS = 2,
  pch = 19,
  col = "black",
  pchLinf = 9,
  colLinf = "red",
  cexLinf = 1.5,
  showLS = TRUE,
  showVB = TRUE,
  ...
)

Arguments

formula	A formula of the form len~age.
data	A data frame in which age and len can be found.
xlab	A string for labeling the x-axis.
ylab	A string for labeling the y-axis.
colLS	A string that indicates the color of the least-squares line.
colRL	A string that indicates the color of the 1:1 reference line.
lwdLS	A numeric that indicates the line width of the least-squares line.
lwdRL	A numeric that indicates the line width of the 1:1 reference line.
ltyLS	A numeric that indicates the line type of the least-squares line.
ltyRL	A numeric that indicates the line type of the 1:1 reference line.
pch	A numeric that indicates the plotting character type for the observed data.
col	A string that indicates the color for the observed data.
pchLinf	A numeric that indicates the plotting character type that indicates the Linf value.
colLinf	A string that indicates the color of the point that indicates the Linf value.
cexLinf	A numeric that indicates the character expansion factor of the point that indicates the Linf value.
showLS	A logical that indicates whether the coefficients from the least-squares fit should be shown on the plot.
showVB	A logical that indicates whether the estimate of Linf and K should be shown on the plot.
...	Other arguments to be passed to the plot function.

Value

None. However, a plot is produced.

Author(s)

Derek H. Ogle, [e-mail]

References

Chapman, D.G. 1981. Statistical problems in dynamics of exploited fisheries populations. Proceedings of the 4th Berkeley Symposium on Mathematics, Statistics and Probability 4:153-168.

Ford, E. 1933. An account of the herring investigations conducted at Plymouth during the years from 1924-1933. Journal of the Marine Biology Association (U.K.), 19:305-384.

Walford, L.A. 1946. A new graphic method of describing the growth of animals. Biological Bulletin, 90:141-147.

See Also

vbStarts

Examples

require(FSA)
data(SMBassWB)
walfordPlot(lencap~agecap,data=SMBassWB)
chapmanPlot(lencap~agecap,data=SMBassWB)

droglenc/FSAmisc documentation built on Jan. 8, 2023, 12:59 a.m.