S18 - HW 4 - Line Chart

CS 725/825 - Spring 2018 - Homework 4 - Line Chart

Q1. What are the marks/channels used and the data/attributes they map to?

The marks for the line chart are connected dots/points that show value and map to: a quantitative value (amount in dollars/y-axis) AND one ordered key attribute (year on the x-axis).

Q2. What does the chart show?

Total donations made (millions/dollars) by the United States each year, 2002 through 2010.

Q3. What are 1-2 interesting insights (i.e., things you learned from the chart)?

For the year 2010, the amount skyrockets to over 100 million. I believe this outlier is the result of an error/mistake in the data.

Q4/References:

https://bl.ocks.org/mbostock/3883245
https://bl.ocks.org/d3noob/23e42c8f67210ac6c678db2cd07a747e
http://www.d3noob.org/2013/01/adding-title-to-your-d3js-graph.html

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<!DOCTYPE html>
<svg width="700" height="400"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    margin = {top: 40, right: 20, bottom: 80, left: 50},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");
  
var x = d3.scaleLinear()
    .rangeRound([0, width]);

var y = d3.scaleLinear()
    .rangeRound([height, 0]);

var line = d3.line()
    .x(function(d) { return x(d.year); })
    .y(function(d) { return y(d.totaldonations); });

d3.tsv("data.tsv", function(d) {
  d.year = d.year;
  // Modified dralph to get Millions scale on Y
  d.totaldonations = +d.totaldonations/1000000;
  return d;
}, function(error, data) {
  if (error) throw error;

x.domain(d3.extent(data, function(d) { return d.year; }));
  y.domain(d3.extent(data, function(d) { return d.totaldonations; }));

g.append("g")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x))
    .select(".domain")
      .remove();

g.append("g")
      .call(d3.axisLeft(y))
    //.append("text")
      //.attr("fill", "#000")
      //.attr("transform", "rotate(-90)")
      //.attr("y", 6)
      //.attr("dy", "0.71em")
      //.attr("text-anchor", "end")
      //.text("Total Donations (in millions $)");
  
    // text label for the y axis
  g.append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 0 - margin.left)
      .attr("x",0 - (height / 2))
      .attr("dy", "1em")
      .style("text-anchor", "middle")
      .text("Amount ($) in Millions");      
  
    // text label for the x axis
  g.append("text")             
      .attr("transform",
            "translate(" + (width / 2) + " ," + 
                           (height + margin.top + 20 ) + ")")
      .style("text-anchor", "middle")
      .text("Year");

g.append("path")
      .datum(data)
      .attr("fill", "none")
      .attr("stroke", "steelblue")
      .attr("stroke-linejoin", "round")
      .attr("stroke-linecap", "round")
      .attr("stroke-width", 1.5)
      .attr("d", line);
  
  g.append("text")
        .attr("x", (width / 2))             
        .attr("y", 0 - (margin.top / 2))
        .attr("text-anchor", "middle")  
        .style("font-size", "16px") 
        .style("text-decoration", "underline")  
        .text("Total U.S. Donations by Year");
});

</script>

https://d3js.org/d3.v4.min.js