JSON array group count

json-array-group-count · version 1.0.0 · JSON & JSONL · free, no key needed

Group an array of JSON objects by exact keys and return the count.

Use when you need to: json array group count · count json array by keys · frequency map json array.

Supported

• json array group count
• count json array by keys
• frequency map json array

Not supported

• group by expression
• other aggregations

Behavior

• Groups objects into an array of records. Each record has the join keys and a "count" key representing the number of matches.
• Output array is ordered by the first appearance of each key tuple.
• Missing or null keys are grouped together and treated as the string 'undefined' or 'null'.

Input

• array (array of object, required): max items 10000
• keys (array of string, required): min items 1; max items 32; each min length 1
• count_name (string, optional): min length 1; max length 64; default "count"

Output

• result (array of object, required)
• groups_count (integer, required)

Limits

• max array items: 10000
• max output items: 10000
• max keys: 32

Example

Request input:

{
  "array": [
    {
      "id": 1,
      "v": "A"
    },
    {
      "id": 2,
      "v": "B"
    },
    {
      "id": 1,
      "v": "C"
    }
  ],
  "keys": [
    "id"
  ]
}

Response:

{
  "result": {
    "result": [
      {
        "id": 1,
        "count": 2
      },
      {
        "id": 2,
        "count": 1
      }
    ],
    "groups_count": 2
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "json-array-group-count",
  "version": "1.0.0",
  "input": {
    "array": [
      {
        "id": 1,
        "v": "A"
      },
      {
        "id": 2,
        "v": "B"
      },
      {
        "id": 1,
        "v": "C"
      }
    ],
    "keys": [
      "id"
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-array-group-count/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"array":[{"id":1,"v":"A"},{"id":2,"v":"B"},{"id":1,"v":"C"}],"keys":["id"]}'

The machine-readable contract is at /v1/tools/json-array-group-count/versions/1.0.0.

CLI

node cli.mjs run json-array-group-count 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• JSON array group by: Group an array of JSON objects by exact keys.
• JSON array anti join: Anti join two JSON arrays of objects on exact keys.
• JSON array index by: Convert an array of objects into a single object indexed by a specific key.
• JSON array sort objects: Stably sort an array of objects by explicit string keys using UTF-16 lexicographic order.
• JSON array count: Count structural occurrences in a JSON array in first-seen order.
• JSON array distinct by: Deduplicate a JSON array of objects based on specific keys.