Transform Array of object using Lodash groupby and map

Question

Here is what I want to do, I want to take the following array and turn it into the array after it. Can anyone point me in the right direction?

Original Data

[{
        "FeatureId": 1,
        "District": "ANE",
        "Temperature": 206,
        "RelativeHumidity": 20,
        "WindSpeed": 5,
        "WindGust": 15
      },
      {
        "FeatureId": 1,
        "District": "ANE",
        "Temperature": 196,
        "RelativeHumidity": 19,
        "WindSpeed": 5,
        "WindGust": 15
      },
      {
        "FeatureId": 2,
        "District": "AMO",
        "Temperature": 203,
        "RelativeHumidity": 54,
        "WindSpeed": 9,
        "WindGust": 18
      },
      {
        "FeatureId": 2,
        "District": "AMO",
        "Temperature": 184,
        "RelativeHumidity": 46,
        "WindSpeed": 12,
        "WindGust": 18
      }]

My Desired Data :

[
  {
    "FeatureId": 1,
    "District": "ANE",
    "TemperatureTrend": [ 206, 196 ],
    "RelativeHumidityTrend": [ 20, 19 ],
    "WindSpeedTrend": [ 5, 5 ],
    "WindGustTrend": [ 15, 15 ]
  },
  {
    "FeatureId": 2,
    "District": "AMO",
    "TemperatureTrend": [ 203, 184 ],
    "RelativeHumidityTrend": [ 54, 46 ],
    "WindSpeedTrend": [ 9, 12 ],
    "WindGustTrend": [ 18, 18 ]
  },

]

I have tried combining groupby and map, but I was unable to resolve the issue. I was also unsure how to log the steps.

Answer 1

Lets use Array.prototype.reduce because it fit the purpose of what you are trying to do.

    const data = [{
        "FeatureId": 1,
        "District": "ANE",
        "Temperature": 206,
        "RelativeHumidity": 20,
        "WindSpeed": 5,
        "WindGust": 15
      },
      {
        "FeatureId": 1,
        "District": "ANE",
        "Temperature": 196,
        "RelativeHumidity": 19,
        "WindSpeed": 5,
        "WindGust": 15
      },
      {
        "FeatureId": 2,
        "District": "AMO",
        "Temperature": 203,
        "RelativeHumidity": 54,
        "WindSpeed": 9,
        "WindGust": 18
      },
      {
        "FeatureId": 2,
        "District": "AMO",
        "Temperature": 184,
        "RelativeHumidity": 46,
        "WindSpeed": 12,
        "WindGust": 18
      }]

// we gonna create from scratch array and populate it
const aggregatedData = data.reduce((memo, element) => {
  const featureId = element.FeatureId

  const elementIndex = memo.findIndex(el => el.FeatureId === featureId)
  if (elementIndex === -1) {
    memo.push({
      FeatureId: featureId,
      District: element.District,
      TemperatureTrend: [element.Temperature],
      RelativeHumidityTrend: [element.RelativeHumidity],
      WindSpeedTrend: [element.WindSpeed],
      WindGustTrend: [element.WindGust]
    })
  } else {
    memo[elementIndex].TemperatureTrend.push(element.Temperature)
    memo[elementIndex].RelativeHumidityTrend.push(element.RelativeHumidity)
    memo[elementIndex].WindSpeedTrend.push(element.WindSpeed)
    memo[elementIndex].WindGustTrend.push(element.WindGust)
  }

  return memo
}, [])

console.log(aggregatedData)

You can check it in codepen