R/sm_panel_label.R

In smin95/sesR: Create Standalone and Composite Plots in 'ggplot2' for Publications

#' Writing a label for each panel of a combined figure
#'
#' @param all_plots
#' all_plots should be a list vector, which should contain all panels
#' that are to be combined into one figure.
#' @param x
#' Location of the label along the x-axis (0 to 1). 0.5 is the middle origin.
#' @param y
#' Location of the label along the y-axis (0 to 1). 0.5 is the middle origin.
#' @param panel_tag
#' A character vector that defines how each panel is enumerated. Options include:
#'  'a', 'A', '1', 'I' or 'i'.'a' is for lowercase letters. 'A' is for uppercase letters. '1'
#'  is for integers. 'I' is for upper case roman numerals. 'i' is for lower case roman numerals.
#'  Each panel will display a unique string based on the set enumeration.
#' @param panel_pretag
#' A character vector that is identical across panels BEFORE the panel_tag.
#' @param panel_posttag
#' A character vector that is identical across panels AFTER the panel_tag.
#' @param text_size
#' Text size of the panel label
#' @param text_color
#' Text color of the panel label
#' @param fontface
#' Fontface of the panel label. Options include "plain", "bold", "italic" and others
#' that are provided by ggplot2.
#' @param ...
#' Additional parameters for adjusting the appearance of the sticker. Same parameters
#' for annotate() from ggplot2.
#'
#' @return
#' It returns a list of plots with panel labels.
#' @export
#' @importFrom utils as.roman
#'
#' @examples
#' library(ggplot2)
#' library(smplot2)
#'
#' ggplot(data = mtcars, mapping = aes(x = drat, y = mpg)) +
#'   geom_point(
#'     shape = 21, fill = "#0f993d", color = "white",
#'     size = 3
#'   ) -> p1
#'
#' ggplot(data = mtcars, mapping = aes(x = drat, y = mpg)) +
#'   geom_point(shape = 21, fill = "#0f993d", color = "white", size = 3) +
#'   sm_hvgrid() -> p2
#'
#' sm_panel_label(list(p1, p2),
#'   x = 0.1, y = 0.9,
#'   panel_tag = "1", panel_pretag = "S", text_size = 4, text_color = "black"
#' )
#'
sm_panel_label <- function(all_plots, x, y, panel_tag = "1", panel_pretag, panel_posttag,
                           text_size = 5.5, text_color = "black", fontface = "plain", ...) {
  if (panel_tag == "A") {
    labelStr <- LETTERS
  } else if (panel_tag == "a") {
    labelStr <- letters
  } else if (panel_tag == "1") {
    labelStr <- as.character(1:length(all_plots))
  } else if (panel_tag == "I") {
    labelStr <- as.character(as.roman(1:length(all_plots)))
  } else if (panel_tag == "i") {
    labelStr <- tolower(as.character(as.roman(1:length(all_plots))))
  } else {
    labelStr <- as.character(1:length(all_plots))
  }

  if (missing(panel_pretag)) {
    labelStr <- labelStr
  } else {
    labelStr <- paste0(panel_pretag, labelStr)
  }

  if (missing(panel_posttag)) {
    labelStr <- labelStr
  } else {
    labelStr <- paste0(labelStr, panel_posttag)
  }

  output <- lapply(1:length(all_plots), function(iPlot) {
    currXlim <- ggplot_build(all_plots[[iPlot]])$layout$panel_params[[1]]$x.range
    currYlim <- ggplot_build(all_plots[[iPlot]])$layout$panel_params[[1]]$y.range

    x_coord <- (max(currXlim) - min(currXlim)) * x + min(currXlim)
    y_coord <- (max(currYlim) - min(currYlim)) * y + min(currYlim)

    all_plots[[iPlot]] + annotate("text",
      label = labelStr[[iPlot]],
      x = x_coord, y = y_coord, size = text_size,
      color = text_color, fontface = fontface, ...
    )
  })
  return(output)
}