Array Functions (MOPS)

`$pivot()`

Signature: $pivot(data, keyFields, pivotField, measures)

Converts row-based data into columnar format by grouping, pivoting, and applying aggregations. It uses % to concatenate multiple keyFields. If in case, invalid input is provided then it will return an empty array.

Parameters

Parameter	Type	Description
`data`	object[]	Array of objects to pivot
`keyFields`	string\|string[]	Grouping column(s) to preserve as rows
`pivotField`	string	Column whose values become new headers
`measures`	[string, ‘SUM’\|‘AVERAGE’][]	Array of [field, aggregation] pairs

Examples

// JSONata
$pivot(
[
    {Region: "West", Product: "A", Sales: 100},
    {Region: "West", Product: "A", Sales: 150},
    {Region: "East", Product: "B", Sales: 200}
],
["Region", "Product"],
"Product",
[["Sales", "SUM"]]
)
// Result
[
    {Region: "West", Product: "A", A: 250},
    {Region: "East", Product: "B", B: 200}
]

`$stdev()`

Signature: $stdev(arr)

Calculates population standard deviation (σ) for an array of numbers using the “n” formula (divided by N).

Parameters

Parameter	Type	Description
`arr`	number[]	Array of numeric values to analyze

Examples

Basic calculation:

$stdev([1, 2, 3, 4, 5]) => 1.4142135623730951 (Population σ for 1-5: √2 ≈ 1.4142)

Empty array handling:
```
$stdev([]) => NaN
```

Single value array:

$stdev([42]) => 0 (No variation when only 1 value exists)