Added sliding() method

Author: aimeos

README.md

@@ -250,6 +250,7 @@ will return:
 <a href="#shuffled">shuffled</a>
 <a href="#skip">skip</a>
 <a href="#slice">slice</a>
+<a href="#sliding">sliding</a>
 <a href="#some">some</a>
 <a href="#sort">sort</a>
 <a href="#sorted">sorted</a>
@@ -488,6 +489,7 @@ will return:
 * [rekey()](#rekey) : Changes the keys according to the passed function
 * [replace()](#replace) : Replaces elements recursively
 * [rtrim()](#rtrim) : Removes the passed characters from the right of all strings
+* [sliding()](#sliding) : Returns a new map containing sliding windows of the original map
 * [splice()](#splice) : Replaces a slice by new elements
 * [strAfter()](#strafter) : Returns the strings after the passed value
 * [strBefore()](#strbefore) : Returns the strings before the passed value
@@ -5463,6 +5465,36 @@ Map::from( ['a', 'b', 'c', 'd'] )->slice( -2, -1 );
 * [take()](#take) - Returns a new map with the given number of items.
 
 
+### sliding()
+
+Returns a new map containing sliding windows of the original map.
+
+```php
+public function sliding( int $size = 2, int $step = 1 ) : self
+```
+
+* @param **int** $size Size of each window
+* @param **int** $step Step size to move the window
+* @return **self&#60;int,array&#60;int&#124;string,mixed&#62;&#62;** New map containing arrays for each window
+
+**Examples:**
+
+```php
+Map::from( [1, 2, 3, 4] )->sliding( 2 );
+// [
+//   [0 => 1, 1 => 2],
+//   [1 => 2, 2 => 3],
+//   [2 => 3, 3 => 4]
+// ]
+
+Map::from( [1, 2, 3, 4] )->sliding( 3, 2 );
+// [
+//   [0 => 1, 1 => 2, 2 => 3],
+//   [2 => 3, 3 => 4, 4 => 5]
+// ]
+```
+
+
 ### some()
 
 Tests if at least one element passes the test or is part of the map.

src/Map.php

@@ -4480,6 +4480,34 @@ public function slice( int $offset, ?int $length = null ) : self
 	}
 
 
+	/**
+	 * Returns a new map containing sliding windows of the original map.
+	 *
+	 * Examples:
+	 *  Map::from( [1, 2, 3, 4] )->sliding( 2 );
+	 *  Map::from( [1, 2, 3, 4] )->sliding( 3, 2 );
+	 *
+	 * Results:
+	 * The first example will return [[0 => 1, 1 => 2], [1 => 2, 2 => 3], [2 => 3, 3 => 4]]
+	 * while the second one will return [[0 => 1, 1 => 2, 2 => 3], [2 => 3, 3 => 4, 4 => 5]]
+	 *
+	 * @param int $size Size of each window
+	 * @param int $step Step size to move the window
+	 * @return self<int,array<int|string,mixed>> New map containing arrays for each window
+	 */
+	public function sliding( int $size = 2, int $step = 1 ) : self
+	{
+		$result = [];
+        $chunks = floor( ( $this->count() - $size ) / $step ) + 1;
+
+		for( $i = 0; $i < $chunks; $i++ ) {
+			$result[] = array_slice( $this->list(), $i * $step, $size, true );
+		}
+
+        return new static( $result );
+	}
+
+
 	/**
 	 * Tests if at least one element passes the test or is part of the map.
 	 *

tests/MapTest.php

@@ -3104,6 +3104,20 @@ public function testSliceNegativeOffsetAndNegativeLength()
 	}
 
 
+	public function testSliding()
+	{
+		$expected = [[0 => 1, 1 => 2], [1 => 2, 2 => 3], [2 => 3, 3 => 4], [3 => 4, 4 => 5]];
+		$this->assertSame( $expected, Map::from( [1, 2, 3, 4, 5] )->sliding( 2 )->toArray() );
+	}
+
+
+	public function testSlidingStep()
+	{
+		$expected = [[0 => 1, 1 => 2, 2 => 3], [2 => 3, 3 => 4, 4 => 5]];
+		$this->assertSame( $expected, Map::from( [1, 2, 3, 4, 5] )->sliding( 3, 2 )->toArray() );
+	}
+
+
 	public function testSome()
 	{
 		$this->assertTrue( Map::from( ['a', 'b'] )->some( 'a' ) );