jq · lesson 17 of 32 · Aggregation

Counting & math

Arrays have length, add, min and max, and the usual arithmetic works: + - * / %.

Example 1Count, total, average, extremes

Document

{
  "team": "Platform",
  "office": { "city": "Berlin", "floor": 3 },
  "members": [
    { "name": "Ada", "age": 36, "role": "lead", "active": true,
      "email": "[email protected]", "skills": ["rust", "sql"] },
    { "name": "Linus", "age": 28, "role": "dev", "active": true,
      "email": null, "skills": ["c", "shell"] },
    { "name": "Grace", "age": 45, "role": "dev", "active": false,
      "skills": ["cobol"] },
    { "name": "Alan", "age": 41, "role": "qa", "active": true,
      "email": "[email protected]", "skills": [] }
  ]
}

Query

.members | map(.age) | (length, add, add / length, min, max)

map(.age) An array of just the ages: [36,28,45,41].
length How many elements → 4.
add The sum → 150.
add / length The average → 37.5.
min, max The smallest and the largest → 28, 45.

Result

Try it in the playground

Good to know

min_by(.age) and max_by(.age) return the whole element, not just the number.
floor and round are there for rounding.