> For the complete documentation index, see [llms.txt](https://boxlang.ortusbooks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://boxlang.ortusbooks.com/boxlang-language/reference/built-in-functions/struct/structreduce.md).

# StructReduce

Run the provided udf against struct to reduce the values to a single output

## Method Signature

```
StructReduce(struct=[structloose], callback=[function], initialValue=[any])
```

### Arguments

| Argument       | Type       | Required | Description                                                                                                                                                                                                                                   | Default |
| -------------- | ---------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- |
| `struct`       | `struct`   | `true`   | The struct to reduce                                                                                                                                                                                                                          |         |
| `callback`     | `function` | `true`   | <p>The function to invoke for each entry in the struct. The function will be passed 4 arguments: the accumulator, they entry key,<br>the<br>current index, and the original struct. The function should return the new accumulator value.</p> |         |
| `initialValue` | `any`      | `false`  | The initial value of the accumulator                                                                                                                                                                                                          |         |

## Examples

### Script Syntax

[Run Example](https://try.boxlang.io/?code=eJxVjkGrwjAQhM%2FmVywpPFooeLc1IAgePAgelHfMM8sztCZlzVpE%2FO8mqQjeZj9mZoe0dX9%2BhCU8QMzkHo2EBcjjGcnLOpIdafePGW416U5n%2Bot978eJ%2BvGsbaYbQnRva6fJdlaKZyPYxvprID6F2M8nLIGmtzWUsHJ3GAhv1vP1oHvGOqMO75O4JQYVLBU8xIwwMLnvAPyAbE1QRcwU7Tyq1hhV5GC6jZKNeNbJ1CsZq5J%2FnnQjRrIB13wZPpugetMdh4FDCXF%2BRC%2BVH1oX)

```java
rainbow = { 
	"Red" : "Whero",
	"Orange" : "Karaka",
	"Yellow" : "Kowhai",
	"Green" : "Kakariki"
};
ui = structReduce( rainbow, ( Any previousValue, Any key, Any value ) => {
	return previousValue & "<dt>#key#</dt><dd>#value#</dd>";
}, "<dl>" ) & "</dl>";
writeDump( rainbow );
writeOutput( ui );

```

### Using Member Function

[Run Example](https://try.boxlang.io/?code=eJxVjsEKwjAQRM%2FmK5YUpELRu60BQfDgQfCgeIxm0dCalDWxlOK%2Fm6R68Db7mJkdktpcbAcrGIBN%2BAEVhyXw0x3J8iKQPUlzwwR3kmQtEz1j09hupLa7S53olhDN11pL0rXm7F0yr0M9jY%2FmhMpfMYcc1qaHlvClrX8eZeOxSKjGfhSvyGAGKwEDmxA6T%2BY%2FAFPglXIiC5msWgRVKSWyFIy3Erxk7yKaGsFDVfQvoi5ZR9rhxj%2Fa%2FDcNZl%2B69671LoewO6AP1rdXdA%3D%3D)

```java
rainbow = { 
	"Red" : "Whero",
	"Orange" : "Karaka",
	"Yellow" : "Kowhai",
	"Green" : "Kakariki"
};
ui = rainbow.reduce( ( Any previousValue, Any key, Any value ) => {
	return previousValue & "<dt>#key#</dt><dd>#value#</dd>";
}, "<dl>" ) & "</dl>";
writeDump( rainbow );
writeOutput( ui );

```

### Additional Examples

[Run Example](https://try.boxlang.io/?code=eJx1kNFLwzAQxp%2Bbv%2BLIg3RQ1ndrB2UUKY5N1k2Zb7E9XVjaSNpszNH%2F3STtlCq%2BfZf73eX7jtW8YqKBGC5AvPnqGW7hQjxvucry1GhaSUkD85BnL64WTL0jJV5nHh%2Bz%2B9%2B45PVhxFdYcl0NA%2FNk82c%2FytNooDF%2BhOVJF5FSVx8%2BCPaKIqaJEMB6vzSAI1PxUMEkIr3M6jdpsuSt0kW7xlIX6F9nAvAhqc%2BgsNGiDZw%2B4LkXRyY0wgTimbWnsNWqBhNVV1i3zXSd5tvFBm6A3gk%2Bo0b89B7SnWtoMbPNpeQNmhwj5ilZbNNpH9qyoQEtnPPPf1h3jm80tMutohHpgv4zauw6wOqIhCHke3ka4hEs9vIa3V3F3OgLFw2MlQ%3D%3D)

```java
animals = { 
	COW : {
		NOISE : "moo",
		SIZE : "large"
	},
	PIG : {
		NOISE : "oink",
		SIZE : "medium"
	},
	CAT : {
		NOISE : "meow",
		SIZE : "small"
	}
};
dump( label="All animals", var=animals );
animalInfo = StructReduce( animals, ( Any result, Any key, Any value ) => {
	return arguments.RESULT & "<li>" & arguments.KEY & "<ul><li>Noise: " & arguments.VALUE.NOISE & "</li><li>Size: " & arguments.VALUE.SIZE & "</li></ul></li>";
}, "<ul>" ) & "</ul>";
// Show result
echo( animalInfo );

```

## Related

* [StructAppend](/boxlang-language/reference/built-in-functions/struct/structappend.md)
* [StructClear](/boxlang-language/reference/built-in-functions/struct/structclear.md)
* [StructCopy](/boxlang-language/reference/built-in-functions/struct/structcopy.md)
* [StructDelete](/boxlang-language/reference/built-in-functions/struct/structdelete.md)
* [StructEach](/boxlang-language/reference/built-in-functions/struct/structeach.md)
* [StructEquals](/boxlang-language/reference/built-in-functions/struct/structequals.md)
* [StructEvery](/boxlang-language/reference/built-in-functions/struct/structevery.md)
* [StructFilter](/boxlang-language/reference/built-in-functions/struct/structfilter.md)
* [StructFind](/boxlang-language/reference/built-in-functions/struct/structfind.md)
* [StructFindKey](/boxlang-language/reference/built-in-functions/struct/structfindkey.md)
* [StructFindValue](/boxlang-language/reference/built-in-functions/struct/structfindvalue.md)
* [StructGet](/boxlang-language/reference/built-in-functions/struct/structget.md)
* [StructGetMetadata](/boxlang-language/reference/built-in-functions/struct/structgetmetadata.md)
* [StructInsert](/boxlang-language/reference/built-in-functions/struct/structinsert.md)
* [StructIsCaseSensitive](/boxlang-language/reference/built-in-functions/struct/structiscasesensitive.md)
* [StructIsOrdered](/boxlang-language/reference/built-in-functions/struct/structisordered.md)
* [StructKeyArray](/boxlang-language/reference/built-in-functions/struct/structkeyarray.md)
* [StructKeyExists](/boxlang-language/reference/built-in-functions/struct/structkeyexists.md)
* [StructKeyList](/boxlang-language/reference/built-in-functions/struct/structkeylist.md)
* [StructKeyTranslate](/boxlang-language/reference/built-in-functions/struct/structkeytranslate.md)
* [StructMap](/boxlang-language/reference/built-in-functions/struct/structmap.md)
* [StructNew](/boxlang-language/reference/built-in-functions/struct/structnew.md)
* [StructNone](/boxlang-language/reference/built-in-functions/struct/structnone.md)
* [StructSome](/boxlang-language/reference/built-in-functions/struct/structsome.md)
* [StructSort](/boxlang-language/reference/built-in-functions/struct/structsort.md)
* [StructToQueryString](/boxlang-language/reference/built-in-functions/struct/structtoquerystring.md)
* [StructToSorted](/boxlang-language/reference/built-in-functions/struct/structtosorted.md)
* [StructUpdate](/boxlang-language/reference/built-in-functions/struct/structupdate.md)
* [StructValueArray](/boxlang-language/reference/built-in-functions/struct/structvaluearray.md)


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