d3.js：仅想比较HH：MM时，时间刻度是否适合x轴？

Question

I want to create charts that compare multiple sets of data. Each object in the set with have a float value for the Y axis and a value for the X axis of the form "2013-01-11T00:00:00Z".

My data structure is as follows:

{
  data_set_a:
    line_1:
      [ { x: x, y: y}, ... ]
    line_2:
      [ { x: x, y: y}, ... ]
  data_set_b:
    line_1:
      [ { x: x, y: y}, ... ]
    line_2:
      [ { x: x, y: y}, ... ]

   ...
  }

NOTE: I have complete control over the data set if something makes more sense/makes this simpler.

For the following questions, I'm only interested in graphing what's in data_set_a. The rest will be separate graphs.

1. While the X axis is dealing with dates, do I want to use an ordinal scale here over a time scale and parse with time.format.iso.parse? Is there a way to tell d3 to just compare "HH:MM" and specify a then also custom format for the X axis text (ie, 12pm | | | 1pm, etc., where | is a tick on 15m intervals)? Or is this task better suited for an ordinal scale where I process the dates before passing off to d3?

2. I am trying to follow along with partial examples demonstrating setting up a single line to use for all lines to be displayed on the chart. How do I set up the scales and domains such that they take into account the range that applies for all lines in the series?

Here is where I am so far: https://gist.github.com/87e52b278c3ab2ada196 . Let's just say my graphs ain't too pretty yet. Thanks in advance.

Answer 1

First, D3 comes with time scales out of the box. Check those out.

Second, in order to setup your scales correctly for all of your data points, you need to compute your bounds over all of your data points:

var data = /* your data from above */,
    points = [].concat(d3.values(data.data_set_a)),
    x_extent = d3.extent(points, function(d) { return d.x; }),
    y_extent = d3.extent(points, function(d) { return d.y; });

With that information, you should be able to setup your scales correctly.