ggtrendline: Add Trendline and Confidence Interval to 'ggplot'

In ggtrendline: Add Trendline and Confidence Interval to 'ggplot'

Add Trendline and Confidence Interval to 'ggplot'

Description

Add trendline and confidence interval of linear or nonlinear regression model to 'ggplot', by using different models built in the 'ggtrendline()' function.
The function includes the following models:
"line2P" (formula as: y=a*x+b),
"line3P" (y=a*x^2+b*x+c),
"log2P" (y=a*ln(x)+b),
"exp2P" (y=a*exp(b*x)),
"exp3P" (y=a*exp(b*x)+c),
"power2P" (y=a*x^b),
and "power3P" (y=a*x^b+c).

Usage

ggtrendline(
  x,
  y,
  model = "line2P",
  linecolor = "black",
  linetype = 1,
  linewidth = 0.6,
  CI.level = 0.95,
  CI.fill = "grey60",
  CI.alpha = 0.3,
  CI.color = "black",
  CI.lty = 2,
  CI.lwd = 0.5,
  summary = TRUE,
  show.eq = TRUE,
  yhat = FALSE,
  eq.x = NULL,
  eq.y = NULL,
  show.Rsquare = TRUE,
  show.pvalue = TRUE,
  Pvalue.corrected = TRUE,
  Rname = 0,
  Pname = 0,
  rrp.x = NULL,
  rrp.y = NULL,
  text.col = "black",
  eDigit = 3,
  eSize = 3,
  xlab = NULL,
  ylab = NULL
)

Arguments

x, y	the x and y arguments provide the x and y coordinates for the 'ggplot'. Any reasonable way of defining the coordinates is acceptable.
model	select which model to fit. Default is "line2P". The "model" should be one of c("line2P", "line3P", "log2P", "exp2P", "exp3P", "power2P", "power3P"), their formulas are as follows: "line2P": y=a*x+b "line3P": y=a*x^2+b*x+c "log2P": y=a*ln(x)+b "exp2P": y=a*exp(b*x) "exp3P": y=a*exp(b*x)+c "power2P": y=a*x^b "power3P": y=a*x^b+c
linecolor	the color of regression line. Default is "black".
linetype	the type of regression line. Default is 1. Notes: linetype can be specified using either text c("blank","solid","dashed","dotted","dotdash","longdash","twodash") or number c(0, 1, 2, 3, 4, 5, 6).
linewidth	the width of regression line. Default is 0.6.
CI.level	level of confidence interval to use. Default is 0.95.
CI.fill	the color for filling the confidence interval. Default is "grey60".
CI.alpha	alpha value of filling color of confidence interval. Default is 0.3.
CI.color	line color of confidence interval. Default is "black".
CI.lty	line type of confidence interval. Default is 2.
CI.lwd	line width of confidence interval. Default is 0.5.
summary	summarizing the model fits. Default is TRUE.
show.eq	whether to show the regression equation, the value is one of c("TRUE", "FALSE").
yhat	whether to add a hat symbol (^) on the top of "y" in equation. Default is FALSE.
eq.x, eq.y	equation position.
show.Rsquare	whether to show the R-square, the value is one of c("TRUE", "FALSE").
show.pvalue	whether to show the P-value, the value is one of c("TRUE", "FALSE").
Pvalue.corrected	if P-value corrected or not, the value is one of c("TRUE", "FALSE").
Rname	to specify the character of R-square, the value is one of c(0, 1), corresponding to c(r^2, R^2).
Pname	to specify the character of P-value, the value is one of c(0, 1), corresponding to c(p, P).
rrp.x, rrp.y	the position for R square and P value.
text.col	the color used for the equation text.
eDigit	the numbers of digits for R square and P value. Default is 3.
eSize	font size of R square and P value. Default is 3.
xlab, ylab	labels of x- and y-axis.

Details

The values of each parameter of regression model can be found by typing trendline_sum function in this package.

The linear models (line2P, line3P, log2P) in this package are estimated by lm function, while the nonlinear models (exp2P, exp3P, power2P, power3P) are estimated by nls function (i.e., least-squares method).

Value

No return value (called for side effects).

References

Ritz C., and Streibig J. C. (2007) Nonlinear Regression with R. Springer.

Greenwell B. M., and Schubert Kabban C. M. (2014) investr: An R Package for Inverse Estimation. The R Journal, 6(1), 90-100.

See Also

ggtrendline, stat_eq, stat_rrp, trendline_sum, nls, selfStart

Examples

# library(ggplot2)
library(ggtrendline)
x <- c(1, 3, 6, 9,  13,   17)
y <- c(5, 8, 11, 13, 13.2, 13.5)

ggtrendline(x, y, model = "line2P")  # default
ggtrendline(x, y, model = "log2P", CI.fill = NA)  # CI lines only, without CI filling

ggtrendline(x, y, model = "exp2P", linecolor = "blue", linetype = 1, linewidth = 1) # set line
ggtrendline(x, y, model = "exp3P", CI.level = 0.99,
            CI.fill = "red", CI.alpha = 0.1, CI.color = NA, CI.lty = 2, CI.lwd = 1.5) # set CI

ggtrendline documentation built on April 27, 2022, 9:06 a.m.