Overview
ListCollection provides methods to transform elements. All transformation methods return collections with sequential integer keys.
map()
Transform each element using a callback and return a new collection.
Signature
public function map(callable $callback): static
callback
callable(TValue, int): TMapValue
required
Callback that receives value and index, returns transformed value.
Examples
$list = new ListCollection([1, 2, 3]);
$mapped = $list->map(fn(int $v): int => $v * 2);
$mapped->all();
// [0 => 2, 1 => 4, 2 => 6]
Signature
public function transform(callable $callback): static
callback
callable(TValue, int): TMapValue
required
Callback that receives value and index, returns transformed value.
Examples
$list = new ListCollection([1, 2, 3]);
$list->transform(fn(int $v): int => $v * 10);
$list->all();
// [0 => 10, 1 => 20, 2 => 30]
Difference from map()
map() returns a new collection (immutable)transform() modifies the collection in place (mutable)- Both ensure sequential keys are maintained
flatMap()
Map each element to an array and flatten the results.
Signature
public function flatMap(callable $callback): static
callback
callable(TValue, int): array
required
Callback that returns an array for each element.
Examples
$list = new ListCollection([1, 2, 3]);
$result = $list->flatMap(fn(int $v): array => [$v, $v * 10]);
$result->all();
// [0 => 1, 1 => 10, 2 => 2, 3 => 20, 4 => 3, 5 => 30]
flatten()
Flatten a multi-dimensional collection into a single level.
Signature
public function flatten($depth = INF): static
Maximum depth to flatten.
Examples
$list = new ListCollection([[1, 2], [3, 4], [5]]);
$result = $list->flatten();
$result->all();
// [0 => 1, 1 => 2, 2 => 3, 3 => 4, 4 => 5]
collapse()
Collapse a collection of arrays into a single flat collection.
Signature
public function collapse(): static
Examples
$list = new ListCollection([[1, 2], [3, 4], [5]]);
$result = $list->collapse();
$result->all();
// [0 => 1, 1 => 2, 2 => 3, 3 => 4, 4 => 5]
pluck()
Extract values for a given field from a collection of arrays or objects.
Signature
public function pluck($value, $key = null): static
The field name to extract.
key
string|null
default:"null"
Not supported. Passing a non-null value throws BadMethodCallException because it would produce associative keys.
Examples
Pluck without key
$list = new ListCollection([
['id' => 10, 'name' => 'Alice'],
['id' => 20, 'name' => 'Bob'],
]);
$result = $list->pluck('name');
$result->all();
// [0 => 'Alice', 1 => 'Bob']
Pluck with key throws exception
$list = new ListCollection([
['id' => 1, 'name' => 'Alice'],
['id' => 2, 'name' => 'Bob'],
]);
// This throws BadMethodCallException
$list->pluck('name', 'id');
reverse()
Reverse the order of elements.
$list = new ListCollection([1, 2, 3]);
$reversed = $list->reverse();
$reversed->all();
// [0 => 3, 1 => 2, 2 => 1]
merge()
Merge with another array or collection.
$list = new ListCollection([1, 2, 3]);
$result = $list->merge([4, 5]);
$result->all();
// [0 => 1, 1 => 2, 2 => 3, 3 => 4, 4 => 5]
concat()
Concatenate values onto the collection.
$list = new ListCollection([1, 2, 3]);
$result = $list->concat([4, 5]);
$result->all();
// [0 => 1, 1 => 2, 2 => 3, 3 => 4, 4 => 5]
replace()
Replace elements at specific indices.
$list = new ListCollection(['a', 'b', 'c']);
$result = $list->replace([1 => 'B']);
$result->all();
// [0 => 'a', 1 => 'B', 2 => 'c']
pad()
Pad the collection to a specified length.
$list = new ListCollection([1, 2]);
$result = $list->pad(5, 0);
$result->all();
// [0 => 1, 1 => 2, 2 => 0, 3 => 0, 4 => 0]
zip()
Zip the collection with another array.
$list = new ListCollection([1, 2, 3]);
$result = $list->zip(['a', 'b', 'c']);
// Returns collection of pairs: [[1, 'a'], [2, 'b'], [3, 'c']]
Key Points
- All transformation methods return
ListCollection with sequential keys (0, 1, 2, …)
map() returns new collection, transform() modifies in placeflatMap(), flatten(), and collapse() reduce nested structurespluck() extracts field values; does not support key parameter (would break list structure)- Results always maintain sequential integer indexing
- Methods can be chained for complex transformations