NYT Covid 19 Data

spec.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
  "data": {
    "url": "https://raw.githubusercontent.com/nytimes/covid-19-data/master/us.csv",
    "format": {"parse": {"deaths": "number"}}
  },
  "transform": [
    {
      "window": [
        {"field": "deaths", "as": "previous_deaths", "op": "lag", "param": 1},
        {"field": "cases", "as": "previous_cases", "op": "lag", "param": 1}
      ]
    },
    {"calculate": "datum.deaths - datum.previous_deaths", "as": "deaths"},
    {"calculate": "datum.cases - datum.previous_cases", "as": "cases"},
    {"filter": {"field": "date", "gt": {"month": 3, "year": 2020}}}
  ],
  "title": {
    "text": "New reported deaths by day in the United States",
    "align": "right",
    "offset": 10
  },
  "view": {"stroke": null},
  "width": 500,
  "layer": [
    {
      "mark": {"type": "bar", "color": "#ccc"},
      "encoding": {
        "x": {
          "field": "date",
          "type": "temporal",
          "timeUnit": "yearmonthdate",
          "axis": {"grid": false, "title": null, "tickCount": 3, "format": "%B"}
        },
        "y": {
          "field": "deaths",
          "type": "quantitative",
          "axis": {"tickCount": 3, "domain": false, "ticks": false, "title": null}
        },
        "tooltip": [
          {"field": "date", "type": "temporal"},
          {"field": "cases", "type": "quantitative", "title": "Cases"},
          {"field": "deaths", "type": "quantitative", "title": "Deaths"}
        ]
      }
    },
    {
      "transform": [
        {
          "window": [{"field": "deaths", "op": "mean", "as": "deaths"}],
          "frame": [-7, 0]
        }
      ],
      "encoding": {
        "x": {"field": "date", "type": "temporal", "timeUnit": "yearmonthdate"},
        "y": {"field": "deaths", "type": "quantitative"}
      },
      "mark": {"type": "line", "color": "#666"}
    }
  ]
}