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<?php |
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/** |
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* Pure viewport grid-clustering engine for the standalone/half-map map. |
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* |
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* Given the in-view listing coordinates and the map zoom, buckets the points |
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* into fixed-pixel grid cells and returns one entry per non-empty cell with its |
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* centroid, member count and member post IDs. The map payload then renders a |
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* single-member cell as a price pin and a multi-member cell as a count bubble — |
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* so listings cluster at every zoom and split apart as the cells shrink. |
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* |
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* PURE — no WordPress calls, so it is unit-testable in isolation |
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* (tests/unit/clusterer-test.php). |
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* |
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* @package Mlsimport |
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*/ |
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|
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if ( ! defined( 'ABSPATH' ) ) { |
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exit; |
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} |
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|
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/** |
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* Grid-clusters {lat,lng,post_id} points into zoom-sized cells. |
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*/ |
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class Mlsimport_Map_Clusterer { |
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|
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/** |
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* Grid-cluster coordinate points into cells sized to the zoom level. |
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* |
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* @param array $coords Objects/arrays with ->lat / ->lng (and optional ->post_id). |
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* @param int $zoom Map zoom; higher zoom => smaller cells => more, tighter cells. |
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* @return array<int,array{lat:float,lng:float,count:int,ids:int[]}> |
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*/ |
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public static function grid( array $coords, int $zoom ): array { |
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// Clamp the zoom to the Web-Mercator tile range so the cell math is sane. |
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$zoom = max( 0, min( 22, $zoom ) ); |
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|
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// Web-Mercator world width in pixels at this zoom is 256 * 2^zoom for 360°. |
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// A ~70px cell keeps clusters visually separated at every zoom level. |
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$world_px = 256.0 * pow( 2, $zoom ); |
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$cell_deg = ( 70.0 / $world_px ) * 360.0; |
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if ( $cell_deg <= 0 ) { |
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$cell_deg = 0.0001; |
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} |
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|
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// Bucket every point into its grid cell, accumulating a running centroid sum. |
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$cells = array(); |
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foreach ( $coords as $c ) { |
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// Read lat/lng/post_id from either an object or an array shape. |
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$lat = is_object( $c ) ? (float) $c->lat : (float) $c['lat']; |
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$lng = is_object( $c ) ? (float) $c->lng : (float) $c['lng']; |
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$id = is_object( $c ) |
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? ( isset( $c->post_id ) ? (int) $c->post_id : 0 ) |
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: ( isset( $c['post_id'] ) ? (int) $c['post_id'] : 0 ); |
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|
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// Cell key = the integer grid coordinate "col:row" the point falls in. |
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$key = ( (int) floor( $lng / $cell_deg ) ) . ':' . ( (int) floor( $lat / $cell_deg ) ); |
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// First point in a cell seeds its accumulator. |
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if ( ! isset( $cells[ $key ] ) ) { |
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$cells[ $key ] = array( |
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'sum_lat' => 0.0, |
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'sum_lng' => 0.0, |
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'count' => 0, |
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'ids' => array(), |
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); |
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} |
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// Fold this point into the cell: sum coords (for the centroid), bump count, |
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// remember the member id. |
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$cells[ $key ]['sum_lat'] += $lat; |
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$cells[ $key ]['sum_lng'] += $lng; |
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$cells[ $key ]['count']++; |
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$cells[ $key ]['ids'][] = $id; |
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} |
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|
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// Emit one entry per non-empty cell: the centroid (sum / count), count and ids. |
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$out = array(); |
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foreach ( $cells as $cell ) { |
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$out[] = array( |
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'lat' => $cell['sum_lat'] / $cell['count'], |
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'lng' => $cell['sum_lng'] / $cell['count'], |
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'count' => (int) $cell['count'], |
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'ids' => $cell['ids'], |
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); |
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} |
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|
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return $out; |
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} |
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} |
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|
