R/blending.R

In nrennie/aRt: Generative Art with R

#' Blending Walk
#'
#' This function generates a random walk.
#'
#' @param n Number of lines. Default 100.
#' @return A numeric vector of length n
#' @noRd

blending_walk <- function(n = 100) {
  x <- stats::runif(n = n - 1)
  x <- c(0, cumsum(x))
  return(x)
}


#' Blending
#'
#' This function generates a generative art ggplot object using a random walk.
#'
#' @param n Number of point. Default 100.
#' @param down Colour to use on bottom. Default "white".
#' @param up Colour to use on top. Default "black".
#' @param s Seed value. Default 1234.
#' @return A ggplot object.
#' @examples
#' blending()
#' @export

blending <- function(n = 100,
                     down = "white",
                     up = "black",
                     s = 1234) {
  plot_data <- withr::with_seed(
    seed = s,
    code = {
      walks <- unlist(purrr::map(.x = 1:n, .f = ~ blending_walk(n = n)))
      plot_data <- expand.grid(x = 1:n, y = 1:n)
      plot_data$colour <- walks
      plot_data
    }
  )
  p <- ggplot2::ggplot(
    data = plot_data,
    mapping = ggplot2::aes(
      x = .data$x,
      y = .data$y,
      fill = .data$colour
    )
  ) +
    ggplot2::geom_raster(interpolate = TRUE) +
    ggplot2::coord_flip(expand = FALSE) +
    ggplot2::scale_fill_gradient(low = down, high = up) +
    theme_aRt("transparent")
  return(p)
}