[BUG] incorrect x-axis range(date) in stacked area plot

[xiaohan2012]

Simply, I am counting the number of items against time intervals.

Code:

{
  "data": {
    "url": "https://www.cs.helsinki.fi/u/hxiao/event_html/data/ukraine/vega/data.json"
  },
  "mark": "area",
  "encoding": {
    "x": {
      "timeUnit": "yearmonthdayhours",
      "field": "datetime",
      "type": "temporal",
      "scale": {
        "nice": "hour"
      },
      "axis": {
        "axisWidth": 0,
        "format": "%m-%d %H:00",
        "labelAngle": 15
      }
    },
    "y": {
      "aggregate": "count",
      "field": "*"
    },
    "color": {
      "field": "series",
      "type": "nominal",
      "scale": {
        "range": "category20"
      }
    }
  },
  "config": {
    "cell": {
      "width": 800,
      "height": 400
    }
  }
}

The bug is on range of x-axis:

• Actual: Feb 8 to Mar, 1.
• Expected: Feb-27 to Mar-03(min and max of the datetime in all items)

Or the web app: https://www.cs.helsinki.fi/u/hxiao/event_html/vega.html

[domoritz]

The issue is that you need to use date (day of the month) instead of day (day of the week). It's very confusing and I will add documentation to https://vega.github.io/vega-lite/docs/timeunit.html

{
  "data": {
    "url": "https://dl.dropboxusercontent.com/u/12770094/data.json"
  },
  "mark": "area",
  "encoding": {
    "x": {
      "timeUnit": "yearmonthdatehours",
      "field": "datetime",
      "type": "temporal"
    },
    "y": {
      "aggregate": "count",
      "field": "*"
    },
    "color": {
      "field": "series",
      "type": "nominal"
    }
  }
}

I'll add the time units that vega-lite supports from https://github.com/vega/vega/wiki/Expressions#datetime-functions to our docs.