Magic: the Gathering

The plot below visualizes the most popular cards in MTG tournament play over time, looking specifically at legacy events (where decks can be made up of essentially any cards out of the 20,000 that have been printed since 1993). I also have a shiny app which offers a more detailed breakdown of all major formats along with annotated timelines of major events over the last decade.

The chart shows the most popular cards during a given month, use the buttons below to navigate by months and years. For each card, there are two values being visualized:
  • Prevalence: the proportion of decks playing at least one copy of the card (bar length and ordering)
  • Average Copies: the average number of copies of the card played in decks playing at least one copy (bar color)

Tournament data from MTGTOP8.com, scraped with rvest.

Legacy metagame breakdown:

Code 
{

  // Using data from R code (below)
  //  Need to transpose data (column-wise => row-wise)
  const dataset = transpose(df_mtg);
  
  // no. of cards to show in plot
  const cards = 30;
  
  // start at most recent month
  var t = 0;
  
  // return 30 rows of data corresponding to time t
  var get_dataset_t = function(t) {
    return dataset.slice((t * cards), (t + 1) * cards);
  };
  
  // convert date to text for header
  var get_date = function() {
  
    const monthNames = [
      "January", "February", "March", "April", "May", "June",
      "July", "August", "September", "October", "November", "December"
    ];

    var date = new Date(dataset_window[0].time);
    
    return monthNames[date.getMonth()] + ", " + date.getFullYear();
    
  };
  
  // accessor for the "key" value of our data (the card name)
  var key = function(d) {
    return d.card;
  };
  
  // initialize data w/ time t = 0
  var dataset_window = get_dataset_t(t);
  
  
  
  // code for drawing card art
  // uris is object w/ elements = urls for different art formats
  var update_img = function(uris) {
  
    // draw full card in bottom right, fading in quickly
    svg.select("#card-full")
      .selectAll("image")
      .data([uris.png])
      .enter()
      .append("svg:image")
      .attr("id", "card-full")
      .attr("xlink:href", (d) => d)
      .attr("x", 2 * w/3)
      .attr("y", h/3 + 30)
      .attr("width", w/4)
      .style("opacity", 0)
      .transition("card-full-in")
      .duration(200)
      .ease(d3.easeLinear)
      .style("opacity", 1);
       
    // draw card art behind bars, fading in slower
    svg.select("#card-art")
      .selectAll("image")
      .data([uris.art_crop])
      .enter()
      .append("svg:image")
      .attr("clip-path", "url(#chart-area)")
      .attr("id", "card-art")
      .attr("xlink:href", (d) => d)
      .attr("x", padding_left)
      .attr("y", 6) 
      .attr("height", h - padding_bottom)
      .style("opacity", 0)
      .transition("card-art-in")
      .duration(500)
      .ease(d3.easeLinear)
      .style("opacity", 0.8); // was .5
  };
  
  // query scryfall api for card art
  var get_art = function(name) {
  
    const reg = /[^\w\s]/g
    var url = name.replace(reg, "").replace(" ", "+").toLowerCase();
    url = "https://api.scryfall.com/cards/named?fuzzy=" + url;
    
    fetch(url)
      .then((response) => response.json())
      // handle multifaced cards, return uris for first face
      .then((data) => data.image_uris ?? data.card_faces[0].image_uris)
      .then((uris) => update_img(uris))
      .catch((error) => {
        console.log("Issue with getting url");
    });   
    
  };
  
  // Remove art before drawing new art
  // transition is breaking, removed for now
  var remove_art = function() {
    svg.select("#card-full")
      .selectAll("image")
      .remove();
    
    svg.selectAll("#card-art")
      .selectAll("image")
//      .transition("card-art-out")
//      .duration(500)
//      .ease(d3.easelinear)
//      .style("opacity", 0)
      .remove();
  };
  
  var mouseover_fun = function(e, d) {
    // on mouseover, dim other bars for card art
    d3.selectAll(".card-bars")
      .attr("stroke-width", 0)
      .attr("opacity", 0.4);
  
    // darken selected bar
    // (alternatively, could adjust stroke-width)
    d3.select(this)
      //.attr("stroke-width", 2)
      //.attr("stroke", "white")
        .attr("opacity", 1)
        .attr("fill", "black");
        
    // finally, draw card art
    get_art(d.card, update_img);
  };
  
  // on mouseout, return to normal
  var mouseout_fun = function(d) {
    d3.selectAll(".card-bars")
      .attr("opacity", 1);
      
    d3.select(this)
        .transition()
        .duration(200)
          .attr("fill", (d) => d3.interpolateViridis(cScale(d.average)));
          
    remove_art();
  };

  // Various parameters governing plot dimensions
  const w = 1200;
  const h = 800;
  const padding_left = 150;
  const padding_right = 35;
  const padding_bottom = 35;
  const anim_len = 1500;
    
  // x and y scales (simple, linear scales)
  var xScale = d3.scaleLinear()
    .domain([0, 1])
    .range([padding_left, w - padding_right]);
  
  var yScale = d3.scaleBand()
    .domain(d3.range(dataset_window.length))
    .rangeRound([0, h - padding_bottom])
    .paddingInner(0.075);
    
  // color scale, with compse w/ viridis
  var cScale = d3.scaleLinear()
    .domain([0, 4]);
  
  // the main svg we will draw on
  var svg = d3.select(".plot-mtg")
    .append("svg")
    .attr("preserveAspectRatio", "xMinYMin meet")
    .attr("viewBox", "0 0" + " " + w + " " + h);
    
    
  // Now, need to set up a few groups
  //  (this allows for use to draw art under the bars)
    
  // Group for axis needs to be first
  svg.append("g").attr("class", "axis");
    
  // set up groups for card art types
  svg.append("g").attr("id", "card-art");
  svg.append("g").attr("id", "card-full");
    
  // Need clipping path (mask) for bottom edge
  //  (Prevents bars + text going below axis)
  //  (Also keeps card art in the right spot)
  svg.append("clipPath")
    .attr("id", "chart-area")
    .append("rect")
    .attr("x", 0)
    .attr("y", 0)
    .attr("width", w - padding_right)
    .attr("height", h - padding_bottom);
    
  // Draw initial bars 
  //  if we want stroke-width on mouseover, need to initialize here
  svg.selectAll(".card-bars")
    .data(dataset_window, key)
    .enter()
    .append("rect")
    .attr("class", "card-bars")
    .attr("clip-path", "url(#chart-area)")
    .attr("x", (d) => xScale(0))
    .attr("width", (d) => xScale(d.prevalence) - xScale(0))
    .attr("y", (d, i) => yScale(i))
    .attr("height", yScale.bandwidth())
    .attr("fill", (d) => d3.interpolateViridis(cScale(d.average)))
//    .attr("stroke-width", "2")
//    .attr("stroke", "white")
    .on("mouseover", mouseover_fun)
    .on("mouseout", mouseout_fun);
    
  // Initial titles:
  svg.selectAll(".card-titles")
    .data(dataset_window, key)
    .enter()
    .append("text")
    .text((d) => d.card + "  ")
    .attr("class", "card-titles")
    .attr("clip-path", "url(#chart-area)")
    .attr("font-size", "13px")
    .attr("text-anchor", "end")
    .attr("style","white-space:pre")
    .attr("x", (d) => xScale(0))
    .attr("y", (d, i) => yScale(i) + yScale.bandwidth() * 5/8);

      
  // x-axis with formatting:
  var xAxis = d3.axisBottom()
    .scale(xScale)
    .ticks(4)
    .tickFormat(d3.format(".0%"));
  
  svg.select(".axis")
    .attr("transform", "translate(0," + (h - padding_bottom) + ")")
    .call(xAxis);
  
  // Note: there is no y-axis
  // instead, we manually handled the bar labels as "text" objects
  // this allows for pretty transitions
        
  // UI element set up:
  // Set ">" button as disabled on start up:
  d3.select("#next").property("disabled", true);
  d3.select("#nnext").property("disabled", true);
    
  // Set time in header
  d3.select("#time")
    .append("text")
    .text(get_date());
    
  // When a button is pressed, start here
  d3.selectAll("button")
    .on("click", function() {
     
      // See which button was clicked
      var buttonID = d3.select(this).attr("id");
            
            // logic to prevent going past bounds of data
            if (buttonID == "prev") {
              if (t < 100) {
                t = t + 1;
        };
            };
            
          if (buttonID == "pprev") {
              if (t <= 88) {
                 t = t + 12;
         }; 
            };
            
          if (buttonID == "next") {
              if (t > 0) {
                t = t - 1;
        };
            };
            
            if (buttonID == "nnext") {
              if (t >= 12) {
                t = t - 12;
        };
            };
            
            // reset data with new value of t
            dataset_window = get_dataset_t(t);
            
            // re-bind new data to bars
      var bars = svg.selectAll(".card-bars")
        .data(dataset_window, key);
        
      // redraw bars
      bars.enter()
        .append("rect")
        .attr("class", "card-bars")
        .attr("clip-path", "url(#chart-area)")
        .attr("x", (d) => xScale(0))
                .attr("y", (d, i) => yScale(i) + h) // start with y value below axis
        .attr("height", yScale.bandwidth())
        .on("mouseover", mouseover_fun)
        .on("mouseout", mouseout_fun)
        .merge(bars)    // Now looking at ALL bars
                .transition("bars-enter")
                .duration(anim_len)
        .attr("width", (d) => xScale(d.prevalence) - xScale(0))
        .attr("y", (d, i) => yScale(i)) // update y value to be correct
        .attr("fill", (d) => d3.interpolateViridis(cScale(d.average)));

      // remove old bars
            bars.exit()
                .transition("bars-exit")
                .duration(anim_len)
                .attr("y", (d, i) => yScale(i) + h) // travel out of window
                .remove();
                
                
            // similar to bars, but now with text:
        var labs = svg.selectAll(".card-titles")
        .data(dataset_window, key);
        
      labs.enter()
        .append("text")
        .text((d) => d.card + "  ")
        .attr("class", "card-titles")
        .attr("clip-path", "url(#chart-area)")
        .attr("font-size", "13px")
        .attr("text-anchor", "end")
        .attr("style","white-space:pre")
        .attr("x", (d) => xScale(0))
                .attr("y", (d, i) => yScale(i) + h)
        .merge(labs)    // Now looking at ALL text
                .transition("labs-enter")
                .duration(anim_len)
        .attr("y", (d, i) => yScale(i) + yScale.bandwidth() * 5/8);
        
       labs.exit()
               .transition("labs-exit")
                 .duration(anim_len)
                 .attr("y", (d, i) => yScale(i) + h)
                 .remove();
                
           // update header with correct time:
       d3.select("#time")
         .select("text")
         .remove();
         
       // Disable/enable buttons as necessary:
       d3.select("#next").property("disabled", t == 0);
       d3.select("#nnext").property("disabled", t < 12);
       
       d3.select("#prev").property("disabled", t == 100);
       d3.select("#pprev").property("disabled", t > 88);
         
       // update month + year
       d3.select("#time")
         .append("text")
         .text(get_date());
      });

}
R Code (Data Wrangling) 
library("tidyverse")
# Reading in data
# Data is scraped from MTGTOP8, details coming soon in a blog post
df_mtg <- read_csv(here::here("posts/2022-11-25-JavaScript-and-Quarto/data/legacy.csv")) 

# Helper to fix encoding of dates
## 2000.05 => 2000-01-01
## 2004.25 => 2000-04-01
fix_time <- function(t) {
  
  year <- floor(t)
  month <- round(20 * (t - year))
  
  lubridate::ymd(paste(year, month, "1"))
  
}

# We don't want basic lands in our viz
basics <- c("Plains", "Mountain", "Forest", "Island", "Swamp")

df_mtg <-
  df_mtg |>
  filter(!is.na(time)) |>
  # Only want to look at top-8 places
  filter(place %in% c(1, 2, 5, 8)) |> 
  mutate(time = fix_time(time)) |>
  filter(lubridate::year(time) >= 2011) |>
  # Don't want cards from sideboard 
  filter(!SB) |>
  filter(!card %in% basics) |>
  # Find count of each card at each timepoint, regardless of place (data is grouped by place)
  group_by(time, card) |>
  summarize(k = n(), copies = sum(copies), decks = sum(decks), total_decks = sum(total_decks), .groups = "drop_last") |> 
  mutate(prevalence = decks / total_decks, average = copies / decks) |>
  # Randomized pertubation to avoid ties return > 30 rows
  top_n(30, wt = (prevalence + rnorm(length(prevalence), sd = .000001))) |> 
  # Break ties w/ average
  arrange(desc(time), desc(prevalence), average) |>
  # For extensibiliity
  mutate(format = "legacy")

# Make `df_mtg` available in ojs chunks:
ojs_define(df_mtg = df_mtg)