From: SpringFlowers AutumnMoon <summercoolness@...>
Date: 2007-09-18T22:04:29+09:00
Subject: Re: how to use tuple as hash key

Rick Denatale wrote:
> On 9/18/07, SpringFlowers AutumnMoon <summercoolness@gmail.com> wrote:
>> >   end
>> > end
>>
>> that is already listed in the initial program.  the main requirement is
>> that I have a list (an array), and how do I use it as a hash key.
> 
> 
> But this code does meet this requirement.
> 
> [i,j] IS an array, so
> 
> h2[[i,j]] = "ha"
> 
> is storing "ha" in the hash with a key which is an array containing
> references to the objects currently referenced by i and j.

my application is this: i have an array with numbers in it.
and i will have a shuffle method to shuffle numbers in that array.
and then i have to use that array's value as a hash key, so as to

h[a] ||= 0  # if nil, then set to 0
h[a] += 1   # to tally up the count

(and repeat the shuffling 100,000 times and keep the count)

so in this case, i don't think rehash will do the job, as rehash merely 
look at what "a" currently references to, and rebuild the hash.  it will 
only have 1 key.

so what I will do is either to use

key = a.dup
h[key] ||= 0
h[key] += 1

or even safer:

key = a.dup
key.freeze
h[key] ||= 0
h[key] += 1

so this is like, to use an array that can change as a tuple.


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