count.json

{
    "id": "count",
    "summary": "Count the number of elements",
    "description": "Gives the number of elements in an array that matches a certain criterion / expression.\n\n**Remarks:**\n\n* By default counts the number of valid elements. A valid element is every element for which ``is_valid()`` returns `true`.\n* To count all elements in a list set the `expression` parameter to boolean `true`.",
    "categories": [
        "arrays",
        "reducer"
    ],
    "parameter_order": ["data", "expression"],
    "parameters": {
        "data": {
            "description": "An array with elements of any data type.",
            "schema": {
                "type": "array",
                "items": {
                    "description": "Any data type is allowed."
                }
            },
            "required": true
        },
        "expression": {
            "description": "An expression that is evaluated against each element in the array. An element is counted only if the expression returns `true`. Defaults to count valid elements in a list (see ``is_valid()``). Setting this parameter to boolean `true` counts all elements in the list.",
            "schema": {
                "anyOf": [
                    {
                        "description": "An expression that is evaluated against each element in the array.",
                        "type": "object",
                        "format": "callback",
                        "parameters": {
                            "x": {
                                "description": "A single value from the array. Any data type could be passed."
                            }
                        }
                    },
                    {
                        "description": "Boolean `true` counts all elements in the list.",
                        "type": "boolean",
                        "const": true
                    },
                    {
                        "description": "`null` counts valid elements in the list.",
                        "type": "null"
                    }
                ],
                "default": null
            }
        }
    },
    "returns": {
        "description": "The counted number of elements.",
        "schema": {
            "type": "number"
        }
    },
    "examples": [
        {
            "arguments": {
                "data": []
            },
            "returns": 0
        },
        {
            "arguments": {
                "data": [1,0,3,2]
            },
            "returns": 4
        },
        {
            "arguments": {
                "data": ["ABC",null]
            },
            "returns": 1
        },
        {
            "arguments": {
                "data": [false,null],
                "expression": true
            },
            "returns": 2
        },
        {
            "arguments": {
                "data": [0,1,2,3,4,5,null],
                "expression": {
                    "gt": {
                        "process_id": "gt",
                        "arguments": {
                            "x": {
                                "from_argument": "element"
                            },
                            "y": 2
                        },
                        "result": true
                    }
                }
            },
            "returns": 3
        }
    ]
}