R/show_prddoy.R

In wqtrends: Assess Water Quality Trends with Generalized Additive Models

#' Plot predictions for GAMs against day of year
#'
#' Plot predictions for GAMs against day of year
#' 
#' @param mod input model object as returned by \code{\link{anlz_gam}}
#' @param ylab chr string for y-axis label
#' @param size numeric indicating line size
#' @param alpha numeric from 0 to 1 indicating line transparency
#' @param base_size numeric indicating base font size, passed to \code{\link[ggplot2]{theme_bw}}
#' 
#' @return A \code{\link[ggplot2]{ggplot}} object
#' @export
#' 
#' @concept show
#' 
#' @examples
#' library(dplyr)
#' 
#' # data to model
#' tomod <- rawdat %>%
#'   filter(station %in% 34) %>%
#'   filter(param %in% 'chl')
#'
#' mod <- anlz_gam(tomod, trans = 'log10')
#' 
#' show_prddoy(mod, ylab = 'Chlorophyll-a (ug/L)')
show_prddoy <- function(mod, ylab, size = 0.5, alpha = 1, base_size = 11){

  # get predictions
  prds <- anlz_prd(mod)

  # get transformation
  trans <- unique(prds$trans)
  
  p <- ggplot2::ggplot(prds, ggplot2::aes(x = doy, group = factor(yr), colour = yr)) + 
    ggplot2::geom_line(ggplot2::aes(y = value), size = size, alpha = alpha) + 
    ggplot2::theme_bw(base_size = base_size) + 
    ggplot2::theme(
      legend.position = 'top', 
      legend.title = ggplot2::element_blank()
    ) + 
    ggplot2::scale_color_viridis_c() + 
    ggplot2::guides(colour = ggplot2::guide_colourbar(barheight = 1, barwidth = 20)) +
    ggplot2::labs(
      x = "Day of year",
      y = ylab
    )
  
  if(trans != 'ident')
    p <- p + ggplot2::scale_y_log10()
  
  return(p)
  
}