R/gridPrint.R

In mfasiolo/mgcViz: Visualisations for Generalized Additive Models

#############################################
#' Plotting plotSmooth objects on a grid
#'
#' @description This is a wrapper for \code{gridExtra::grid.arrange}, which allows to
#'              plot several \code{plotSmooth} objects on a grid.
#' 
#' @param ... arguments to be passed to \code{gridExtra::grid.arrange}.
#' @details This function simply extracts the \code{ggplot} objects contained in any 
#'          object of class \code{plotSmooth} and passes them to \code{gridExtra::grid.arrange}.
#' @name gridPrint
#' @importFrom gridExtra grid.arrange
#' @examples
#' library(mgcViz)
#' n  <- 1e3
#' x1 <- rnorm(n)
#' x2 <- rnorm(n)
#' dat <- data.frame("x1" = x1, "x2" = x2,
#'                   "y" = sin(x1) + 0.5 * x2^2 + pmax(x2, 0.2) * rnorm(n))
#' b <- bam(y ~ s(x1)+s(x2), data = dat, method = "fREML", discrete = TRUE)
#' b <- getViz(b)
#' 
#' o1 <- plot( sm(b, 1) ) + l_fitLine() + l_ciLine() 
#' o2 <- plot( sm(b, 2) ) + l_fitLine() + l_ciLine() 
#' qpl <- qq(b)
#' 
#' # All on one page, method 1:
#' gridPrint(o1, o2, qpl, ncol = 2)
#' 
#' # All on one page, method 2:
#' gridPrint(grobs = list(o1, o2, qpl), ncol = 2)
#' 
#' # Works also when some ggplot objects are present
#' gridPrint(o1, o2, qpl, ggplot(), ncol = 2)
#'
#' @rdname gridPrint
#' @export gridPrint
#'
gridPrint <- function(...){
  
  arg <- list(...)
  
  # Extract ggplot objects from "plotSmooth" objects in "..."
  ii <- unlist( lapply(arg, inherits, what = "plotSmooth") )
  if ( length(ii) ) {
    arg[ii] <- lapply(arg[ii], "[[", "ggObj")
  }
  
  # Extract ggplot objects from "plotSmooth" objects in "..."$grobs
  if( !is.null(arg$grobs) ){
    ii <- unlist( lapply(arg$grobs, inherits, what = "plotSmooth") )
    if ( length(ii) ) {
      arg$grobs[ii] <- lapply(arg$grobs[ii], "[[", "ggObj")
    }
  }

  out <- do.call("grid.arrange", arg)
  
  return( invisible(out) )
  
}