Gantt Charts in R using Plotly

Gantt Charts are a great way to keep track of timelines, progress of specific aspects of the project and resource utilization. Project Managers and anyone familiar with Microsoft Project would be familiar with Gantt Charts.

Here’s how to make one in R using Plotly’s R API.

library(plotly)

# Read in data
df <- read.csv("https://cdn.rawgit.com/plotly/datasets/master/GanttChart-updated.csv", stringsAsFactors = F)

# Convert to dates
df$Start <- as.Date(df$Start, format = "%m/%d/%Y")

# Sample client name
client = "Sample Client"

# Choose colors based on number of resources
cols <- RColorBrewer::brewer.pal(length(unique(df$Resource)), name = "Set3")
df$color <- factor(df$Resource, labels = cols)

# Initialize empty plot
p <- 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(df) - 1)){
  p <- add_trace(p,
                 x = c(df$Start[i], df$Start[i] + df$Duration[i]),  # x0, x1
                 y = c(i, i),  # y0, y1
                 mode = "lines",
                 line = list(color = df$color[i], width = 20),
                 showlegend = F,
                 hoverinfo = "text",
                 
                 # Create custom hover text
                 
                 text = paste("Task: ", df$Task[i], "<br>",
                              "Duration: ", df$Duration[i], "days<br>",
                              "Resource: ", df$Resource[i]),
                 
                 evaluate = T  # needed to avoid lazy loading
                 )
}


# Add information to plot and make the chart more presentable

p <- layout(p,
            
            # Axis options:
            # 1. Remove gridlines
            # 2. Customize y-axis tick labels and show task names instead of numbers
            
            xaxis = list(showgrid = F, tickfont = list(color = "#e6e6e6")),
            
            yaxis = list(showgrid = F, tickfont = list(color = "#e6e6e6"),
                         tickmode = "array", tickvals = 1:nrow(df), ticktext = unique(df$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(df$Duration), " days<br>",
                                 "Total Resources: ", length(unique(df$Resource)), "<br>"),
                   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