Php array element deduplication

Php array element deduplication 1. remove duplicates using the array_unique method

To deduplicate array elements, we usually use the array_unique method. this method can be used to deduplicate the elements in the array.

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Output:

Array(    [0] => 1    [1] => 2    [2] => 3    [3] => 4    [4] => 5    [5] => 6    [6] => 7    [7] => 8    [8] => 9)123456789101112

After deduplication, the key values are not sorted in order. you can use array_values to re-sort the key values.

2. de-duplication efficiency using the array_unique method

 '; Echo 'run time:'. (float) ($ endtime-$ starttime) * 1000). 'Ms
'; Echo 'use memory :'. getUseMemory ();/*** get memory usage * @ return float */function getUseMemory () {$ use_memory = round (memory_get_usage (true)/, 2 ). 'KB'; return $ use_memory;}/*** get microtime * @ return float */function getMicrotime () {list ($ usec, $ sec) = explode ('', microtime (); return (float) $ usec + (float) $ sec;}?> 1234567891011121314151617181920212223242526272829303132333435363738394041

Unique count: 99
Run time: 653.39303016663 ms
Use memory: 5120kb

The array_unique method is used to remove duplicates. the running time is about 650 ms, and the memory usage is about 5 m.

3. faster array deduplication method

Php has a key-value interchange method, array_flip. we can use this method to remove duplicates. because of key-value swaps, the original duplicate values will become the same key.
Then perform another key-value swap. you can replace the key and value to complete deduplication.

 '; Echo 'run time:'. (float) ($ endtime-$ starttime) * 1000). 'Ms
'; Echo 'use memory :'. getUseMemory ();/*** get memory usage * @ return float */function getUseMemory () {$ use_memory = round (memory_get_usage (true)/, 2 ). 'KB'; return $ use_memory;}/*** get microtime * @ return float */function getMicrotime () {list ($ usec, $ sec) = explode ('', microtime (); return (float) $ usec + (float) $ sec;}?> 123456789101112131415161718192021222324252627282930313233343536373839404142

Unique count: 99
Run time: 12.840032577515 ms
Use memory: 768kb

The array_flip method is used to remove duplicates. the running time is about 18 ms, and the memory usage is about 2 m.

Therefore, the array_flip method is less than the array_unique method, and the memory usage is reduced by 98%;