From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2013-07-24T15:50:32+09:00
Subject: Re: how to create structure like bellow

On Wed, Jul 24, 2013 at 12:14 AM, Expert Alart <lists@ruby-forum.com> wrote:
> Hi
> thanks you are right, i might be thinking too hard .. may be it can be
> done easily ... but still i am in puzzle ...
>
>
> The value will come from a file , its has raw data like bellow
>
> xx-xx-xx-xx-a-z16d1
> xx-xx-xx-xx-b-z16d1
> ...................................
> xx-xx-xx-xxx-b-z15a7
> xx-xx-xx-xxx-b-z15a7
> ...................................
>
>
> So to avoid mistakes
> i will  have a manual entry , example  there will be 8 Groups
>  z16,z15,z1f........z1d

So, the "identifier" of the row, are those three characters that come
2 before the end?
If so, you can extract them easily witha  regex:

2.0.0p195 :002 > id = "xx-xx-xx-xxx-b-z15a7".match(/(...)..$/).captures[0]
 => "z15"

> as you can see those lines in  file has those entry
>
> so  i need to have like this
>  z16
> xx-xx-xx-xx-a-z16d1
> xx-xx-xx-xx-b-z16d1
> z15
> xx-xx-xx-xxx-b-z15a7
> xx-xx-xx-xxx-b-z15a7
>
> Now run  a loop to do snmp like
>
> for z15 , go each list
>     power=`snmp xx-xx-xx-xxx-b-z15a7`
>     total=power+toal
>
> end
>
>
> so the same for rest 8 ..
> to make it simple ...
> i am just planning to have array where i will insert those number
> manually..
> object={z16,z15....z1d}
>
> now
>
> object.each do |obj|
>     Read from the file
>       if line entry has "z16"
>            power=`snmp xx-xx-xx-xx-a-z16d1`
>               power_total=power+total_power
>
>       end
>         store this value into  z16
>
> end
>
>
> So when i will represent  the value in report it will be
>
> Total power for Z16=12
> Total power for Z13 =12
> ..................................
> ...........................
>
> may be can be done more simple

There's a very neat trick with hashes by which you can set a default
value for a Hash, so when you access a key that doesn't exist, it
returns that value. This lets you do things like this pretty easily:

h = Hash.new(0) # h will return 0 for non existing keys

h["z16"] += 3

this is equivalent to h["z16"] = h["z16"] + 3
and as h has a default value of 0, the second h["z16"] will return 0
the first time, adding 3 and storing it. So you could do it like this
(mix of pseudocode and code):

totals = Hash.new(0)
for each line of the file
  id = line.match(/(...)..$/).captures[0]
  power=`snmp #{line}`
  totals[id] += power
end

Hope this helps,

Jesus.