From: Siep Korteling <s.korteling@...>
Date: 2008-04-25T00:39:23+09:00
Subject: Re: twolak@sktydev.com - Found word(s) list error in the Text body - Re: Hash keys

Tim Wolak wrote:
> (...)
> Basically what I'm trying to do here is gather the account balances and
> account numbers and store them in a hash and if there are accounts with 
> the
> same number to store their balances as an array in the hash value to add
> them later when I iterate over the hash.
> 
> If there is a better way to do this that I'm not thinking of please 
> share
> with me so I can better my ruby knowledge.
> 
> Thanks!
> Tim

The following code does not store an array in a hash, it just stores a 
running total:

DATA.gets
#DATA is the stuff below __END__
#you can treat it like a file.
#DATA.gets just gets the first line and ignores it.

totalled = Hash.new(0)
#Thanks to the (0) parameter, totalled will return 0 if a key is not 
found.

DATA.each do |line|
  ar_line = line.split(",")
  account, balance = ar_line[0], ar_line[1].to_f
  totalled[account] = totalled[account] + balance
  #this line does the job. For the first line
  #read in the loop, the key "101" is not found in the hash
  #so it returns 0. Then the balance is added.
  #The key and the new (running) balance are stored.
  #A shorter way to write this is:
  #totalled[account] +=  balance
end
p totalled

__END__
account,balance
101,100.00
102,500.00
101,-57.00
103,0.50
102,1


##end code

prints: {"101"=>43.0, "102"=>501.0, "103"=>0.5}

If you really need the hash with an array, replace the first line with:
   totalled = Hash.new([])
(giving a 'default value' of an empty array); Also replace this line:
   totalled[account] = totalled[account] + balance
with
   totalled[account]=totalled[account]<<balance
HTH,

Siep


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