Show day and month from epoch timestamp with vega-lite

Question

I have this vega-lite spec and I'd like to show the day and month in the x axis from an epoch timestamp:

{
  "data": {
    "values": [
      {"date": "1325376000000", "price": 0},
      {"date": "1325462400000", "price": 100},
      {"date": "1325548800000", "price": 30}
    ]
  },
  "mark": "line",
  "encoding": {
    "x": {"field": "date"},
    "y": {"field": "price", "type": "quantitative"}
  },
  "width": "container"
}

This is the current result:

I tried using transformations with no luck.

Answer 1

You mean like this?

{
  "data": {
    "values": [
      {"date": "1325376000000", "price": 0},
      {"date": "1325462400000", "price": 100},
      {"date": "1325548800000", "price": 30}
    ],
    "format": {"parse": {"date": "date:'%Q'"}}
  },
  "mark": "line",
  "encoding": {
    "x": {"field": "date", "timeUnit": "yearmonthdate", "type": "ordinal"},
    "y": {"field": "price", "type": "quantitative"}
  },
  "width": "container"
}