Here’s a very useful function to retrieve a randomly weighted key from an associative array in PHP.<\/p>\n
Sometimes you need to fetch random elements from a collection but you need some elements to have a little more chance than others to be fetched (business rules or whatever…)<\/p>\n
[php]
\nsrand(time()); \/\/dont call this inside the function or you’ll get same result always
\nfunction getRandomWeightedKey($weighted_elements, $default_key) {
\n $weighted_ranges = array();
\n $weight_offset = 0;<\/p>\n
\/\/if you know weights are not gonna change you could
\n \/\/move this part of the code to another place and cache it
\n \/\/for better performance. Specially if you have a lot of weighted elements
\n foreach ($weighted_elements as $key => $weight) {
\n $weighted_ranges[]=array(‘key’=>$key,
\n ‘range’=>array(intval($weight_offset),intval($weight_offset+$weight)));
\n $weight_offset += $weight;
\n }<\/p>\n
\/\/get a random number between the 0 and the maximum
\n $r = rand(0,$weight_offset);<\/p>\n
foreach ($weighted_ranges as $range) {
\n if ($r >= $range[‘range’][0] && $r < $range[‘range’][1]) {
\n return $range[‘key’];
\n }
\n }<\/p>\n
\/\/this shouldn’t happen but Mr. Justin Case.
\n return $default_key;
\n}<\/p>\n
\/\/how to use it. (weights don’t necessarily need to add to 100,
\n\/\/but it helps me to visualize things basing weights on 100
\n$weights = array("a" => 25, "b" => 25, "c" => 50);<\/p>\n
$randomKey = getRandomWeightedKey($weights, "c");
\n[\/php]<\/p>\n
It should be trivial porting this code to the language of your choice. Enjoy.<\/p>\n","protected":false},"excerpt":{"rendered":"
Here’s a very useful function to retrieve a randomly weighted key from an associative array in PHP. Sometimes you need to fetch random elements from a collection but you need some elements to have a little more chance than others to be fetched (business rules or whatever…) [php] srand(time()); \/\/dont call this inside the function […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[15],"tags":[],"class_list":["post-2193","post","type-post","status-publish","format-standard","hentry","category-code"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5Unzf-zn","jetpack-related-posts":[{"id":574,"url":"https:\/\/www.gubatron.com\/blog\/facebook-php-source-code\/","url_meta":{"origin":2193,"position":0},"title":"Facebook PHP Source Code","author":"gubatron","date":"August 14, 2007","format":false,"excerpt":"Ok, so one guy got to see Facebook's source code on his screen, probably due to some bad upgrade, lord knows why, the code appeared on his screen, he then copied and pasted it to some forums, and then Facebook lawyers were threatening him. Too late!, it's all over the\u2026","rel":"","context":"In "Code"","block_context":{"text":"Code","link":"https:\/\/www.gubatron.com\/blog\/category\/code\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2851,"url":"https:\/\/www.gubatron.com\/blog\/how-to-process-thousands-of-wordpress-posts-without-hitting-or-raising-memory-limits\/","url_meta":{"origin":2193,"position":1},"title":"How to process thousands of WordPress posts without hitting or raising memory limits.","author":"gubatron","date":"November 13, 2012","format":false,"excerpt":"So you need to write a script that processes all the posts in your wordpress database, you don't need to use the stupid wordpress loop because you're not writing web facing code, you might just need to fix some metadata on each one of the posts, but every time you\u2026","rel":"","context":"In "Code"","block_context":{"text":"Code","link":"https:\/\/www.gubatron.com\/blog\/category\/code\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":4101,"url":"https:\/\/www.gubatron.com\/blog\/top-5-weighted-exercises-for-climbers\/","url_meta":{"origin":2193,"position":2},"title":"Top 5 Weighted Exercises for Climbers","author":"gubatron","date":"June 10, 2024","format":false,"excerpt":"I try doing these AFTER my climbing sessions or on rest days.\u00a0 Climbers need more than just time on the wall to excel. 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