R/themes.R

In metan: Multi Environment Trials Analysis

#' Personalized theme for ggplot2-based graphics
#'
#' @param grid Control the grid lines in plot. Defaults to `"both"` (x and
#'   y major grids). Allows also `grid = "x"` for grids in x axis only,
#'   `grid = "y"` for grid in y axis only, or `grid = "none"` for no
#'   grids.
#' @param col.grid The color for the grid lines
#' @param color.background The color for the panel background.
#' @param alpha An alpha value for transparency (0 < alpha < 1).
#' @param color A color name.
#' @param n The number of colors. This works well for up to about eight colours,
#'   but after that it becomes hard to tell the different colours apart.
#'
#' @name themes
#' @description
#' * `theme_metan()`: Theme with a gray background and major grids.
#' * `theme_metan_minimal()`: A minimalistic theme with half-open frame, white
#'   background, and no grid. For more details see [ggplot2::theme()].
#' * `transparent_color()`: A helper function to return a transparent color
#' with Hex value of "#000000FF"
#' * `ggplot_color()`: A helper function to emulate ggplot2 default color
#' palette.
#' * `alpha_color()`: Return a semi-transparent color based on a color name
#' and an alpha value. For more details see [grDevices::colors()].
#' @md
#' @export
#' @author Tiago Olivoto \email{tiagoolivoto@@gmail.com}
#'
theme_metan = function (grid = "none", col.grid = "white", color.background = "gray95") {
  if(grid == "x"){
    grid_x <- element_line(color = col.grid)
    grid_y <- element_blank()
  }
  if(grid == "y"){
    grid_y <- element_line(color = col.grid)
    grid_x <- element_blank()
  }
  if(grid == "both"){
    grid_y <- element_line(color = col.grid)
    grid_x <- element_line(color = col.grid)
  }
  if(grid == "none"){
    grid_x <- element_blank()
    grid_y <- element_blank()
  }
  theme_gray() %+replace% # allows the entered values to be overwritten
    theme(axis.ticks.length = unit(.2, "cm"),
          axis.text = element_text(size = 12, colour = "black"),
          axis.title = element_text(size = 12, colour = "black"),
          axis.ticks = element_line(colour = "black"),
          plot.title = element_text(face = "bold", hjust = 0, vjust = 3),
          plot.subtitle = element_text(face = "italic", hjust = 0, vjust = 2, size = 8),
          legend.position = c(0.85, 0.1),
          legend.title = element_blank(),
          legend.key = element_rect(fill = NA, colour = NA),
          legend.background = element_rect(fill = NA, colour = NA),
          legend.box.background = element_rect(fill = NA, colour = NA),
          plot.margin = margin(0.3, 0.1, 0.1, 0.1, "cm"),
          panel.grid.major.x = grid_x,
          panel.grid.major.y = grid_y,
          panel.grid.minor = element_blank(),
          panel.background = element_rect(fill = color.background),
          panel.border = element_rect(colour = "black", fill = NA, size = 1),
          strip.background = element_rect(color = "black", fill = NA))
}

#' @name themes
#' @export
#'
theme_metan_minimal = function () {
  theme_bw() %+replace% # allows the entered values to be overwritten
    theme(axis.ticks.length = unit(.2, "cm"),
          plot.title = element_text(face = "bold", hjust = 0, vjust = 3),
          plot.subtitle = element_text(face = "italic", hjust = 0, vjust = 2, size = 8),
          axis.ticks = element_line(colour = "black"),
          legend.position = c(0.85, 0.1),
          legend.key = element_rect(fill = NA, colour = NA),
          legend.background = element_rect(fill = NA, colour = NA),
          legend.box.background = element_rect(fill = NA, colour = NA),
          plot.margin = margin(0.3, 0.1, 0.1, 0.1, "cm"),
          legend.title = element_blank(),
          axis.text = element_text(colour = "black"),
          panel.grid = element_blank(),
          panel.border = element_blank(),
          panel.background = element_blank(),
          axis.line.x.bottom = element_line(),
          axis.line.y.left = element_line(),
          strip.background = element_blank())
}

#' @name themes
#' @export
transparent_color <- function() {
  return("#FFFFFF00")
}
#' @name themes
#' @export
#' @importFrom grDevices hcl
ggplot_color <- function(n) {
  # adapted from https://stackoverflow.com/a/8197703
  hues = seq(15, 375, length = n + 1)
  hcl(h = hues, l = 65, c = 100)[1:n]
}
#' @name themes
#' @importFrom grDevices col2rgb rgb
#' @export
alpha_color <- function(color, alpha = 50) {
  rgb_v <- col2rgb(color)
  return(
    rgb(rgb_v[1],
        rgb_v[2],
        rgb_v[3],
        maxColorValue = 255,
        alpha = (100 - alpha) * 255 / 100)
  )
}