D3: Accessing Objects in Bound array using variables

Question

I'm trying to animate monthly data across a map. I've stored each month's data all together within an array, and when I try to bind the data like so with: .data(data.January) it will work. However, when using the variable tracking the current month selected with .data(data.monthName) it returns a TypeError in the console and does not render the rest of the application.

My guess is that I'm accessing the key values incorrectly, and that d3 has a unique way of handling that.

Below is the function that doesn't work. (update() is fired when the slider controls change months.)

d3.json("data/avg_revisit.json", function(data) {
color.domain([20, 0]);
  function update() {
        var monthName = getMonthName(currentMonth);
        colored_bars.selectAll("rect")
          .data(data.monthName)
          .enter()
          .append("rect")
            .attr("width", getLandWidth())
            .attr("class", "bars")
            .attr("height", function(d) {
              return projection([0, d.latitude - 0.5])[1] - projection([0, d.latitude])[1];
            })
            .attr("opacity", 0.6)
            .style("fill", function(d) {
              //Get data value
              var value = d.average_revisit;

              if (value) {
                      //If value exists…
                      return color(value);
              } else {
                      //If value is undefined…
                      return "#ccc";
              }
             })
             //Define position of each rectangle by it's latitude from the data
            .attr("transform", function(d) {
              return "translate(" + projection([-180, d.latitude]) + ")"
            });
          }

altocumulus · Accepted Answer · 2016-04-18 08:07:10Z

2

Use data[monthName] instead of data.monthName. If you are using a variable to access the key of an object you must use object[string variable].

edited Apr 18, 2016 at 8:07

altocumulus

21.7k13 gold badges65 silver badges86 bronze badges

answered Apr 18, 2016 at 6:51

Lingaraju E V

5032 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

alrightmight Over a year ago

Thank you! That fixed it. I knew something small was tripping me up. Thanks so much.

Gerardo Furtado Over a year ago

It also works for invalid names. For example, if you have a key named "1st", you can't write data.1st, but you can write data["1st"].

Collectives™ on Stack Overflow

D3: Accessing Objects in Bound array using variables

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related