Re: random index in array - no duplicates

[crazyinsomniac]

An option is to use splice. It's probably not the most efficient (you can always benchmark to make sure), but otherwise you can't get away with a single pass (at least not using rand, there probably is a perl module to only spit out unique random values, but its destined to be less efficient than just keeping track yourself).

 

______crazyinsomniac_____________________________ Of all the things I've lost, I miss my mind the most. perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"

[Abigail-II]

A splice isn't efficient. It's essentially quadratic in the size of the array, while a shuffle is linear.

Or to be more precise. If you have an array of size N and you want to draw M elements from it (without duplicates), splice will take time proportional to N * M, while the suffle will take time proportional to N + M (or just M if you get a reference to the array).

Abigail