R/grid.R

In mrjoh3/c3: 'C3.js' Chart Library

#' @rdname grid.c3
#' @family grid
#' @export
grid <- function(c3,
                 axis,
                 show = TRUE,
                 lines = NULL,
                 ticks = NULL,
                 ...){
  UseMethod('grid')
}

#' @title C3 Grid
#' @description Modify grid and line elements on both x and y axis
#'
#' @param c3 c3 htmlwidget object
#' @param axis character 'x' or 'y'
#' @param show boolean
#' @param ticks boolean placeholder. Not yet implemented in \href{http://c3js.org/reference.html#grid-y-ticks}{C3.js}
#' @param lines dataframe with options:
#' \itemize{
#'  \item{value}{: numeric, character or date depending on axis}
#'  \item{text}{: character (optional)}
#'  \item{class}{: character css class (optional)}
#'  \item{position}{: character one of 'start', 'middle', 'end' (optional)}
#' }
#' @param ... additional options passed to the grid object
#'
#' @family c3
#' @family grid
#' @return c3
#' @export
#'
#' @examples
#'  mtcars %>%
#'    c3(x = 'mpg', y = 'wt', group = 'cyl') %>%
#'    c3_scatter() %>%
#'    grid('y') %>%
#'    grid('x', show = FALSE, lines = data.frame(value=c(17, 21),
#'                                               text= c('Line 1', 'Line 2')))
#'
grid.c3 <- function(c3,
                    axis,
                    show = TRUE,
                    lines = NULL,
                    ticks = NULL,
                    ...){

  stopifnot(!missing(axis))

  grid <- list(show = show,
               lines = lines, # show inside axis
               ticks = ticks # only for yAxis
  )

  grid <- modifyList(grid, list(...))

  grid <- Filter(Negate(function(x) is.null(unlist(x))), grid)

  c3$x$grid[[axis]] <- grid

  return(c3)

  }