How did passenger class affect survival on the Titanic?

A simple, yet powerful correlation.

This was the first thing I made in D3. A simple yet powerful correlation displayed in a bar graph.

I didn’t have a thorough understanding of D3 back then, so I wasn’t able to implement traditional filtering and enter-update-exit. Instead, I redrew the whole chart and rebound new data depending on which passenger class was selected. In the data, “1” corresponded to surviving and “0” corresponded to dying. So I set up two variables, survived and died, and updated them depending on the number of 1’s and 0’s in the data.

This is the full code for the chart. (I was still using jQuery back then!)

$(document).ready(function(){

function draw(passengerClass) {

  var survived = 0;
  var died = 0;
  console.log(passengerClass);

  titanicData.forEach(function(person, i) {
    // console.log(person.Pclass);
    if (person.PClass === passengerClass || passengerClass === "all") {
      console.log("YES");

      if (person.Survived == "1") {
        survived = survived + 1;
      } else if (person.Survived == "0") {
        died = died + 1;
      }

    }
  });

  var bars = svg.selectAll("rect")
    .data([{
        category: "survived",
        value: survived
      },
      {
        category: "died",
        value: died
      }
    ]);

  function styleBars(rect) {
    rect
      .attr("height", function(d) {
        return yScale(d.value);
      })
      .attr("width", barWidth)
      .attr("x", function(d, i) {
        return i * (w / 2);
      })
      .attr("y", function(d) {
        return h - yScale(d.value);
      });
  }


  bars.enter()
    .append("rect")
    .attr("id", function(d) {
      return d.category;
    })
    .attr("fill", function(d) {
      if (d.category === "survived") {
        return "#34495e";
      } else if (d.category === "died") {
        return "grey";
      }
    })
    .call(styleBars);

  bars.transition().duration(1000)
      .call(styleBars);

  var labels = svg.selectAll("text")
    .data([{
        category: "survived",
        value: survived
      },
      {
        category: "died",
        value: died
      }
    ]);

  labels.enter().append("text")
    .attr("y", 80)
    .text(function(d) {
      return d.value;
    })
    .attr("x", function(d, i) {
      return i * (w / 2) + barWidth/2;
    })
    .attr("text-anchor", "middle");

  labels
    .text(function(d) {
      return d.value;
    });

}

var titanicData;
var h, w, barPadding, barWidth, yScale, svg;


d3.csv("titanic.csv", function(error, data) {
  w = 200;
  h = 300;
  barPadding = 10;
  barWidth = (w/2) - barPadding;


  yScale = d3.scaleLinear()
    .domain([0, 1313])
    .range([0, 300]);


  svg = d3.select(".svg-container-1")
      .append("svg")
      .attr("width", w)
      .attr("height", h);

  console.log(data);
  titanicData = data;

  $("#first-class").on("click", function() {
    draw("1st");
  });

  $("#second-class").on("click", function() {
    draw("2nd");
  });

  $("#third-class").on("click", function() {
    draw("3rd");
  });

  $("#total").on("click", function() {
    draw("all");
  });

  draw("all");

  svg.append("text")
    .attr("x", barWidth/2)
    .attr("y", h - barPadding)
    .attr("text-anchor", "middle")
    .attr("fill", "white")
    .text("Lived");

  svg.append("text")
    .attr("x", (w/2) + (barWidth/2))
    .attr("y", h - barPadding)
    .attr("text-anchor", "middle")
    .attr("fill", "white")
    .text("Died");
  });
})

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