How to quickly remove duplicate elements from php arrays

This article mainly introduces the method of quickly deduplicating PHP array elements, which has a good reference value. Let’s take a look at it with the editor

1. Use the array_unique method to deduplicate

To deduplicate array elements, we generally use the array_unique method, using This method can remove duplicate elements from the array.

Output:

Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 [7] => 8 [8] => 9 )

After deduplication, the key values will be out of order , you can use array_values to reorder the key values.

2. Use array_unique method to remove duplicates for efficiency

'; echo 'run time:'.(float)(($endtime-$starttime)*1000).'ms
'; echo 'use memory:'.getUseMemory(); /** * 获取使用内存 * @return float */ function getUseMemory(){ $use_memory = round(memory_get_usage(true)/1024,2).'kb'; return $use_memory; } /** * 获取microtime * @return float */ function getMicrotime(){ list($usec, $sec) = explode(' ', microtime()); return (float)$usec + (float)$sec; } ?>

unique count:99
run time:653.39303016663 ms
use memory:5120kb

Use thearray_uniquemethod to remove duplicates. The running time takes about650msand the memory usage is about5m

3. Faster array deduplication method

PHP has a key-value exchange method array_flip. We can use this method to deduplicate, because key-value exchange, The original duplicate value will become the same key.

Then perform a key-value exchange again, and exchange the keys and values back to complete deduplication.

'; echo 'run time:'.(float)(($endtime-$starttime)*1000).'ms
'; echo 'use memory:'.getUseMemory(); /** * 获取使用内存 * @return float */ function getUseMemory(){ $use_memory = round(memory_get_usage(true)/1024,2).'kb'; return $use_memory; } /** * 获取microtime * @return float */ function getMicrotime(){ list($usec, $sec) = explode(' ', microtime()); return (float)$usec + (float)$sec; } ?>

unique count:99
run time:12.840032577515ms
use memory:768kb

USEarray_flipMethod to remove duplicates, the running time takes about18ms, and the memory usage is about2m

, so using thearray_flipmethod to remove duplicates is better than usingarray_uniqueThe method running time is reduced by98%, and the memory usage is reduced by4/5;

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