Add the Diversified Sampler aggregation

lib/Elastica/Aggregation/DiversifiedSampler.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Elastica\Aggregation;
+
+/**
+ * Class DiversifiedSampler.
+ *
+ * @see https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-diversified-sampler-aggregation.html
+ */
+class DiversifiedSampler extends AbstractSimpleAggregation
+{
+    /**
+     * Set the number of top-scoring documents to be returned from each shard.
+     *
+     * @return $this
+     */
+    public function setShardSize(int $shardSize): self
+    {
+        return $this->setParam('shard_size', $shardSize);
+    }
+
+    /**
+     * Set the maximum number of documents to be returned per value.
+     *
+     * @return $this
+     */
+    public function setMaxDocsPerValue(int $max): self
+    {
+        return $this->setParam('max_docs_per_value', $max);
+    }
+
+    /**
+     * Instruct Elasticsearch to use direct field data or ordinals/hashes of the field values to execute this aggregation.
+     * The execution hint will be ignored if it is not applicable.
+     *
+     * @return $this
+     */
+    public function setExecutionHint(string $hint): self
+    {
+        return $this->setParam('execution_hint', $hint);
+    }
+}

lib/Elastica/QueryBuilder/DSL/Aggregation.php

@@ -9,6 +9,7 @@
 use Elastica\Aggregation\Cardinality;
 use Elastica\Aggregation\DateHistogram;
 use Elastica\Aggregation\DateRange;
+use Elastica\Aggregation\DiversifiedSampler;
 use Elastica\Aggregation\ExtendedStats;
 use Elastica\Aggregation\Filter;
 use Elastica\Aggregation\Filters;
@@ -441,4 +442,14 @@ public function sampler($name): Sampler
     {
         return new Sampler($name);
     }
+
+    /**
+     * diversified sampler aggregation.
+     *
+     * @see https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-diversified-sampler-aggregation.html
+     */
+    public function diversified_sampler(string $name): DiversifiedSampler
+    {
+        return new DiversifiedSampler($name);
+    }
 }

test/Elastica/Aggregation/DiversifiedSamplerTest.php

@@ -0,0 +1,120 @@
+<?php
+
+namespace Elastica\Test\Aggregation;
+
+use Elastica\Aggregation\DiversifiedSampler;
+use Elastica\Aggregation\Sum;
+use Elastica\Document;
+use Elastica\Index;
+use Elastica\Mapping;
+use Elastica\Query;
+
+class DiversifiedSamplerTest extends BaseAggregationTest
+{
+    protected function _getIndexForTest(): Index
+    {
+        $index = $this->_createIndex(null, true, 2);
+
+        $mapping = new Mapping([
+            'price' => ['type' => 'integer'],
+            'color' => ['type' => 'keyword'],
+        ]);
+        $index->setMapping($mapping);
+
+        $routing1 = 'first_routing';
+        $routing2 = 'second_routing';
+
+        $index->addDocuments([
+            (new Document(1, ['price' => 5, 'color' => 'blue']))->setRouting($routing1),
+            (new Document(2, ['price' => 8, 'color' => 'blue']))->setRouting($routing1),
+            (new Document(3, ['price' => 1, 'color' => 'blue']))->setRouting($routing1),
+            (new Document(4, ['price' => 3, 'color' => 'red']))->setRouting($routing1),
+            (new Document(5, ['price' => 1.5, 'color' => 'red']))->setRouting($routing1),
+            (new Document(6, ['price' => 2, 'color' => 'green']))->setRouting($routing1),
+            (new Document(7, ['price' => 5, 'color' => 'blue']))->setRouting($routing2),
+            (new Document(8, ['price' => 8, 'color' => 'blue']))->setRouting($routing2),
+            (new Document(9, ['price' => 1, 'color' => 'red']))->setRouting($routing2),
+            (new Document(10, ['price' => 3, 'color' => 'red']))->setRouting($routing2),
+        ]);
+
+        $index->refresh();
+
+        return $index;
+    }
+
+    /**
+     * @group unit
+     */
+    public function testToArray()
+    {
+        $expected = [
+            'diversified_sampler' => [
+                'field' => 'color',
+                'shard_size' => 1,
+                'max_docs_per_value' => 2,
+                'execution_hint' => 'map',
+            ],
+            'aggs' => [
+                'price_sum' => [
+                    'sum' => [
+                        'field' => 'price',
+                    ],
+                ],
+            ],
+        ];
+
+        $agg = new DiversifiedSampler('price_diversified_sampler');
+        $agg->setField('color');
+
+        $agg->setShardSize(1);
+        $agg->setMaxDocsPerValue(2);
+        $agg->setExecutionHint('map');
+
+        $childAgg = new Sum('price_sum');
+        $childAgg->setField('price');
+
+        $agg->addAggregation($childAgg);
+
+        $this->assertEquals($expected, $agg->toArray());
+    }
+
+    /**
+     * @dataProvider shardSizeAndMaxDocPerValueProvider
+     * @group functional
+     */
+    public function testSamplerAggregation(int $shardSize, int $maxDocPerValue, int $docCount)
+    {
+        $agg = new DiversifiedSampler('price_diversified_sampler');
+        $agg->setField('color');
+
+        $agg->setShardSize($shardSize);
+        $agg->setMaxDocsPerValue($maxDocPerValue);
+
+        $childAgg = new Sum('price_sum');
+        $childAgg->setField('price');
+
+        $agg->addAggregation($childAgg);
+
+        $query = new Query();
+        $query->addAggregation($agg);
+        $results = $this->_getIndexForTest()->search($query)->getAggregation('price_diversified_sampler');
+
+        $this->assertEquals($docCount, $results['doc_count']);
+    }
+
+    public function shardSizeAndMaxDocPerValueProvider()
+    {
+        return [
+            [1, 1, 2],
+            [2, 1, 4],
+            [3, 1, 5],
+            [4, 1, 5],
+            [1, 2, 2],
+            [2, 2, 4],
+            [3, 2, 6],
+            [4, 2, 8],
+            [5, 2, 9],
+            [6, 2, 9],
+        ];
+    }
+}

test/Elastica/QueryBuilder/DSL/AggregationTest.php

@@ -58,6 +58,7 @@ public function testInterface()
         $this->_assertImplemented($aggregationDSL, 'sum_bucket', Aggregation\SumBucket::class, ['name']);
         $this->_assertImplemented($aggregationDSL, 'adjacency_matrix', Aggregation\AdjacencyMatrix::class, ['name']);
         $this->_assertImplemented($aggregationDSL, 'sampler', Aggregation\Sampler::class, ['name']);
+        $this->_assertImplemented($aggregationDSL, 'diversified_sampler', Aggregation\DiversifiedSampler::class, ['name']);
 
         $this->_assertNotImplemented($aggregationDSL, 'children', ['name']);
         $this->_assertNotImplemented($aggregationDSL, 'geo_bounds', ['name']);