From: "Eric I." <rubytraining@...>
Date: 2008-06-04T11:49:15+09:00
Subject: Re: Remove Parts of a String

On Jun 3, 7:15 pm, Dan __ <major_general_...@hotmail.com> wrote:
> Eric, your hash idea seems very interesting.  I'm assuming I'd have to
> update the hash every time I changed the entry in the database though,
> correct?

Or you can do it the other way around, if that's more convenient.  You
can add a new item to the Hash, and regenerate the String, and then
save it to your db.  See below where I assign to the variable
back_to_string.

====

ratings = "12343:3,73820:1,183874:8"

ratings_array = ratings.split(/[,:]/).map { |str| str.to_i }
# we now have array w/ ids & ratings
interleaved:
#   [12343, 3, 73820, 1, 183874,
8]

ratings_by_id = Hash[*ratings_array]
# we convert that into a hash where keys are ids and values are
ratings:
#   {12343=>3, 183874=>8,
73820=>1}

# and now we can look up an id and get either its rating or, if
there
# is no rating,
nil

r1 = ratings_by_id[183874]
p r1

r2 = ratings_by_id[77777]
p r2

# add a new rating to the hash
ratings_by_id[62541] = 4

# regenerate the String
back_to_string = ratings_by_id.map { |k, v| "#{k}:#{v}"}.join(',')
puts back_to_string

====

Eric

====

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