aggregation

spec.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "description": "Plot showing a 30 day rolling average with raw values in the background.",
  "title":"Learning Vega",
  "data": {
    "url": "https://gist.githubusercontent.com/DevinBayly/a4bbb3b0f1293f0b4d373bc99e1917cc/raw/ca4376a0255d00885866be5b7f395743833321e9/vega_data.json"
  },
  
  "width": 400,
  "height": 300,
  "mark": "bar",
  "encoding": {
    "x": {"field": "value", "type": "quantitative", "title": "Index","bin": true},
    "y":{"aggregate":"count"}
    
  }
  

}