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Transformations

Calculating New Values

Use these when you want to add a new column whose value is derived from existing columns.

---

Calculate — DF_CALCULATE

Create a new column by performing a calculation on existing columns.

Use this when: you want to compute something that isn't directly in your data, like cost from kWh and a tariff rate, or the difference between two readings.

Available operations: add, subtract, multiply, divide, percentage, difference (change from previous row), expression (write your own formula).

Before

Code
[
  { "device": "AC-01", "kwh": 1.2, "tariff_per_kwh": 0.35 },
  { "device": "AC-02", "kwh": 1.7, "tariff_per_kwh": 0.35 },
  { "device": "AC-03", "kwh": 0.9, "tariff_per_kwh": 0.35 }
]

After — adding a cost_sgd column

Code
[
  { "device": "AC-01", "kwh": 1.2, "tariff_per_kwh": 0.35, "cost_sgd": 0.42 },
  { "device": "AC-02", "kwh": 1.7, "tariff_per_kwh": 0.35, "cost_sgd": 0.60 },
  { "device": "AC-03", "kwh": 0.9, "tariff_per_kwh": 0.35, "cost_sgd": 0.32 }
]

Code
{
  "type": "DF_CALCULATE",
  "config": {
    "outputField": "cost_sgd",
    "operation": "multiply",
    "fieldA": "kwh",
    "fieldB": "tariff_per_kwh"
  }
}

For a custom formula, use "operation": "expression":

Code
{
  "type": "DF_CALCULATE",
  "config": {
    "outputField": "net_cost",
    "operation": "expression",
    "expression": "(kwh * tariff_per_kwh) - discount"
  }
}

---

Cumulative — DF_CUMULATIVE

Add a running total, running average, or moving average as a new column.

Use this when: you want to track how a value accumulates over time — for example, total energy consumed so far this month, or a smoothed rolling average to reduce noise.

Available types: sum (running total), average (running average), movingAverage (average of last N rows).

Before

Code
[
  { "hour": 1, "kwh": 1.2 },
  { "hour": 2, "kwh": 1.5 },
  { "hour": 3, "kwh": 0.9 },
  { "hour": 4, "kwh": 1.8 }
]

After — adding a running total

Code
[
  { "hour": 1, "kwh": 1.2, "cumulative_kwh": 1.2 },
  { "hour": 2, "kwh": 1.5, "cumulative_kwh": 2.7 },
  { "hour": 3, "kwh": 0.9, "cumulative_kwh": 3.6 },
  { "hour": 4, "kwh": 1.8, "cumulative_kwh": 5.4 }
]

Code
{
  "type": "DF_CUMULATIVE",
  "config": {
    "field": "kwh",
    "type": "sum",
    "outputField": "cumulative_kwh"
  }
}

For a moving average over the last 3 rows:

Code
{
  "type": "DF_CUMULATIVE",
  "config": {
    "field": "kwh",
    "type": "movingAverage",
    "window": 3,
    "outputField": "rolling_avg_kwh"
  }
}