Question

Is there a hash implementation around that doens’t remember key values? I have to make a giant hash but I don’t care what the keys are.

Edit:

Ruby’s hash implementation stores the key’s value. I would like hash that doesn’t remember the key’s value. It just uses the hash function to store your value and forgets the key. The reason for this is that I need to make a hash for about 5 gb of data and I don’t care what the key values are after creating it. I only want to be able to look up the values based on other keys.

Edit Edit:

The language is kind of confusing. By key’s value I mean this:

hsh[‘value’] = data

I don’t care what ‘value’ is after the hash function stores data in the hash.

Edit^3:

Okay so here’s what I am doing: I am generating every 35-letter (nucleotide) kmer for a set of multiple genes. Each gene has an ID. The hash looks like this:

kmers = { 'A...G' => [1, 5, 3], 'G...T' => [4, 9, 9, 3]  }

So the hash key is the kmer, and the value is an array containing IDs for the gene(s)/string(s) that have that kmer.

I am querying the hash for kmers in another dataset to quickly find matching genes. I don’t care what the hash keys are, I just need to get the array of numbers from a kmer.

>> kmers['A...G']
=> [1, 5, 3]

>> kmers.keys.first
=> "Sorry Dave, I can't do that"

Answer 1

Even if there was an oddball hash that just recorded existence (which is how I understand the question) you probably wouldn’t want to use it, as the built-in Hash would be simpler, faster, not require a gem, etc. So just set…

 h[k] = k

…and call it a day…