R/gantt.R

In DoktorMike/datools: A set of useful tools for machine learning consulting using R

#' Plot a Gantt chart using plotly
#'
#' A Gantt chart is plotted using plotly. The format of the data.frame given to
#' the function should be
#'   Task      Start Duration Resource
#' Task 1 2016-01-01       50        A
#' Task 2 2016-02-20       25        B
#' Task 3 2016-01-01      100        C
#' Task 4 2016-04-10       60        C
#' Task 5 2016-06-09       30        C
#' Task 6 2016-04-10      150        A
#' Task 7 2016-09-07       80        B
#' Task 8 2016-11-26       10        B
#' where the duration is given in days.
#'
#' Originally source appeared on \url{https://www.r-bloggers.com/gantt-charts-in-r-using-plotly/}.
#'
#' @param mydf the data.frame containing the information of the project
#' @param client the client name given as a string
#' @param brewerpalname the name of the palette to use from RColorBrewer which defaults to "Set3"
#' @importFrom plotly add_trace plot_ly layout
#' @importFrom RColorBrewer brewer.pal
#'
#' @return a plotly object
#' @export
#'
#' @examples
#' tmpdf <- structure(list(
#'   Task = c(
#'     "Task 1", "Task 2", "Task 3", "Task 4",
#'     "Task 5", "Task 6", "Task 7", "Task 8"
#'   ), Start = structure(c(
#'     16801,
#'     16851, 16801, 16901, 16961, 16901, 17051, 17131
#'   ), class = "Date"),
#'   Duration = c(50L, 25L, 100L, 60L, 30L, 150L, 80L, 10L), Resource = c(
#'     "A",
#'     "B", "C", "C", "C", "A", "B", "B"
#'   )
#' ), .Names = c(
#'   "Task", "Start",
#'   "Duration", "Resource"
#' ), row.names = c(NA, -8L), class = "data.frame")
#' plotGantt(tmpdf, "Sample Client")
plotGantt <- function(mydf, client, brewerpalname = "Set3") {
  # Choose colors based on number of resources
  cols <- RColorBrewer::brewer.pal(length(unique(mydf$Resource)), name = brewerpalname)
  mydf$color <- factor(mydf$Resource, labels = cols)

  # Initialize empty plot
  p <- plotly::plot_ly()

  # Each task is a separate trace
  # Each trace is essentially a thick line plot
  # x-axis ticks are dates and handled automatically

  for (i in 1:(nrow(mydf) - 1)) {
    p <- plotly::add_trace(p,
      x = c(mydf$Start[i], mydf$Start[i] + mydf$Duration[i]),
      y = c(i, i), mode = "lines",
      line = list(color = mydf$color[i], width = 20), showlegend = F,
      hoverinfo = "text",

      text = paste(
        "Task: ", mydf$Task[i], "\n",
        "Duration: ", mydf$Duration[i], "days\n",
        "Resource: ", mydf$Resource[i]
      ),
      evaluate = T # needed to avoid lazy loading
    )
  }

  p <- plotly::layout(p,
    xaxis = list(showgrid = F, tickfont = list(color = "#e6e6e6")),
    yaxis = list(
      showgrid = F, tickfont = list(color = "#e6e6e6"),
      tickmode = "array", tickvals = 1:nrow(mydf),
      ticktext = unique(mydf$Task), domain = c(0, 0.9)
    ),

    # Annotations
    annotations = list(
      # Add total duration and total resources used
      # x and y coordinates are based on a domain of [0,1] and not
      # actual x-axis and y-axis values

      list(
        xref = "paper", yref = "paper", x = 0.80, y = 0.1,
        text = paste0(
          "Total Duration: ", sum(mydf$Duration), " days\n",
          "Total Resources: ", length(unique(mydf$Resource)), "\n\n"
        ),
        font = list(color = "#ffff66", size = 12),
        ax = 0, ay = 0, align = "left"
      ),

      # Add client name and title on top
      list(
        xref = "paper", yref = "paper", x = 0.1, y = 1, xanchor = "left",
        text = paste0("Gantt Chart: ", client),
        font = list(color = "#f2f2f2", size = 20, family = "Times New Roman"),
        ax = 0, ay = 0, align = "left"
      )
    ),

    plot_bgcolor = "#333333",
    # Chart area color
    paper_bgcolor = "#333333"
  ) # Axis area color
  p
}