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# BoxSetMap

Apply a transform function to every element of a Set and collect the deduplicated results into a new Set of the same variant.

The source Set is not modified. The callback receives the element value, its 1-based ordinal position, and the original Set.

## Method Signature

```
BoxSetMap(set=[set], callback=[function:Function])
```

### Arguments

| Argument   | Type                | Required | Description                                                               | Default |
| ---------- | ------------------- | -------- | ------------------------------------------------------------------------- | ------- |
| `set`      | `set`               | `true`   | The source set to transform.                                              |         |
| `callback` | `function:Function` | `true`   | Receives {@code (value, ordinal, set)} and returns the transformed value. |         |

## Examples

### Transform each element and return a new Set

The callback receives each value and must return the replacement value.

```java
s = [ 1, 2, 3, 4, 5 ].toSet();
doubled = s.map( ( Any v ) => v * 2 );
writeOutput( doubled.size() );

```

Result: 5

### Map strings to uppercase

```java
s = setOf( "apple", "banana", "cherry" );
upper = s.map( ( Any v ) => uCase( v ) );
writeOutput( upper.contains( "APPLE" ) );

```

Result: true

## Related

* [BoxSetAdd](/boxlang-language/reference/built-in-functions/set/boxsetadd.md)
* [BoxSetAddAll](/boxlang-language/reference/built-in-functions/set/boxsetaddall.md)
* [BoxSetClear](/boxlang-language/reference/built-in-functions/set/boxsetclear.md)
* [BoxSetContains](/boxlang-language/reference/built-in-functions/set/boxsetcontains.md)
* [BoxSetContainsAll](/boxlang-language/reference/built-in-functions/set/boxsetcontainsall.md)
* [BoxSetDifference](/boxlang-language/reference/built-in-functions/set/boxsetdifference.md)
* [BoxSetEach](/boxlang-language/reference/built-in-functions/set/boxseteach.md)
* [BoxSetEquals](/boxlang-language/reference/built-in-functions/set/boxsetequals.md)
* [BoxSetEvery](/boxlang-language/reference/built-in-functions/set/boxsetevery.md)
* [BoxSetFilter](/boxlang-language/reference/built-in-functions/set/boxsetfilter.md)
* [BoxSetFind](/boxlang-language/reference/built-in-functions/set/boxsetfind.md)
* [BoxSetIntersection](/boxlang-language/reference/built-in-functions/set/boxsetintersection.md)
* [BoxSetIsDisjointFrom](/boxlang-language/reference/built-in-functions/set/boxsetisdisjointfrom.md)
* [BoxSetIsEmpty](/boxlang-language/reference/built-in-functions/set/boxsetisempty.md)
* [BoxSetIsSubsetOf](/boxlang-language/reference/built-in-functions/set/boxsetissubsetof.md)
* [BoxSetIsSupersetOf](/boxlang-language/reference/built-in-functions/set/boxsetissupersetof.md)
* [BoxSetNone](/boxlang-language/reference/built-in-functions/set/boxsetnone.md)
* [BoxSetReduce](/boxlang-language/reference/built-in-functions/set/boxsetreduce.md)
* [BoxSetReject](/boxlang-language/reference/built-in-functions/set/boxsetreject.md)
* [BoxSetRemove](/boxlang-language/reference/built-in-functions/set/boxsetremove.md)
* [BoxSetRemoveAll](/boxlang-language/reference/built-in-functions/set/boxsetremoveall.md)
* [BoxSetRetainAll](/boxlang-language/reference/built-in-functions/set/boxsetretainall.md)
* [BoxSetSome](/boxlang-language/reference/built-in-functions/set/boxsetsome.md)
* [BoxSetSymmetricDifference](/boxlang-language/reference/built-in-functions/set/boxsetsymmetricdifference.md)
* [BoxSetToArray](/boxlang-language/reference/built-in-functions/set/boxsettoarray.md)
* [BoxSetToList](/boxlang-language/reference/built-in-functions/set/boxsettolist.md)
* [BoxSetUnion](/boxlang-language/reference/built-in-functions/set/boxsetunion.md)
* [ObjectToSet](/boxlang-language/reference/built-in-functions/set/objecttoset.md)
* [SetNew](/boxlang-language/reference/built-in-functions/set/setnew.md)
* [SetOf](/boxlang-language/reference/built-in-functions/set/setof.md)
* [StructKeySet](/boxlang-language/reference/built-in-functions/set/structkeyset.md)
* [StructValueSet](/boxlang-language/reference/built-in-functions/set/structvalueset.md)
* [ToSet](/boxlang-language/reference/built-in-functions/set/toset.md)


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