Random Array Element Access: rand() vs. array_rand()
 Often
during development you come upon a situtation where you have to randomly
pick an element from an array. The PHP guys did us a favor and created
the array_rand() function, but I suspected it wasn't as fast as it
could be. Below are the comparisons between array_rand() and code
that produces the exact same result using the rand() function.
Test Environment: Linux, Apache, PHP 4.3.11 with
PHP loaded using FastCGI. Zend Optimizer 2.5.7 installed. What's
Zend Optimizer?
Test Setup: Code constructs listed below. For loops
used to have enough iterations to make the script execution time calculatable.
Refresh the page to execute a new trial!
| Comparisons |
| array_rand()
|
- Execution time: 4.66
ms
- Average: 3.03
ms over 943 trials
|
| code using rand()
|
- Execution time: 1.81
ms
- Average: 2.05
ms over 943 trials
|
| Results |
| Test |
Avg Execution Time |
Comparative Graph - (longer is slower, 100% is the fastest time)
|
| array_rand() |
3.03 ms |
148% |
| code using rand() |
2.05 ms |
100% |
Discussion: As the above results show, array_rand()
is much slower than the code we made using rand(). It's not even close,
and from my own experimentation (not shown here,) I have found that
the gap widens as the number of elements increases. Lesson? Don't
use array_rand().
|
