R/RPregression.R

In RPregression: A Simple Regression and Plotting Tool

#' R package for regression analysis
#'
#' This package allows you to run a regression analysis, generate a regression table,
#' create a scatter plot, and download the results. It uses 'stargazer' for generating
#' regression tables and 'ggplot2' for creating plots. With just two lines of code, you can
#' perform a regression analysis, visualize the results, and save the output.
#'
#' @param x The independent variable.
#' @param y The dependent variable.
#' @param table The format for the regression table ("text", "html", or "latex").
#' @param plot Logical, whether to generate a plot.
#' @param xlab Label for x-axis in the plot.
#' @param ylab Label for y-axis in the plot.
#' @param title The title for the regression table and plot.
#' @param subtitle Subtitle for the plot (optional).
#' @param caption Caption for the plot (optional).
#' @param plottheme Theme for the plot (default is "theme_grey()").
#' @param download Logical, whether to save the regression table as a text file.
#' @param color_points Color for points in the plot (default is "black").
#' @param color_line Color for the regression line (default is "red").
#' @param ci Logical, whether to include confidence interval in the plot (default is TRUE).
#' @param sd Logical, whether to include standard deviation bars in the plot (default is FALSE).
#' 
#' @return If plot is TRUE, a plot is generated. Otherwise, a regression table is printed.
#' @examples
#' RPregression(mtcars$mpg, mtcars$wt, table = "text", title = "Regression Analysis",
#' plot = TRUE, xlab = "mpg", ylab = "wt", plottheme = "theme_grey()", download = FALSE)
#'
#' @export
RPregression <- function(x, y, table = "text", plot = FALSE,
                         xlab = "", ylab = "", title = "", subtitle = "", caption = "", 
                         plottheme = "theme_grey()", download = FALSE, 
                         color_points = "black", color_line = "red", 
                         ci = TRUE, sd = FALSE) {
  if (!requireNamespace("stargazer", quietly = TRUE)) {
    stop("The 'stargazer' package is required but not installed.")
  }
  
  if (!requireNamespace("ggplot2", quietly = TRUE)) {
    stop("The 'ggplot2' package is required but not installed.")
  }
  
  x_name <- deparse(substitute(x))
  y_name <- deparse(substitute(y))
  
  formula <- as.formula(paste(y_name, "~", x_name))
  
  model <- lm(formula, data = data.frame(x, y))
  
  if (table == "text") {
    regression <- stargazer::stargazer(model, type = "text", title = title)
  } else if (table == "html") {
    regression <- stargazer::stargazer(model, type = "html", title = title)
  } else if (table == "latex") {
    regression <- stargazer::stargazer(model, type = "latex", title = title)
  } else {
    stop("Please select either 'text', 'html', or 'latex' for the table format.")
  }
  
  if (plot) {
    p <- ggplot2::ggplot(data = data.frame(x, y), ggplot2::aes(x, y)) +
      ggplot2::geom_point(color = color_points) +
      ggplot2::geom_smooth(method = "lm", se = ci, color = color_line) +
      ggplot2::labs(x = xlab, y = ylab, title = title, subtitle = subtitle, caption = caption) +
      eval(parse(text = plottheme))
    
    if (sd) {
      p <- p + ggplot2::geom_errorbar(aes(ymin = predict(model) - sd(residuals(model)), ymax = predict(model) + sd(residuals(model))), width = 0.2, color = "gray")
    }
    
    if (download) {
      sink(paste0(title, ".txt"))
      print(stargazer::stargazer(model, type = "text", title = title))
      sink()
    }
    
    return(list(model_summary = summary(model), plot = p, regression_table = regression))
  } else {
    return(list(model_summary = summary(model), regression_table = regression))
  }
}