From: Todd Benson <caduceass@...>
Date: 2008-09-29T00:59:48+09:00
Subject: Re: Merging hashes and having trouble with variable scope!

On Sun, Sep 28, 2008 at 6:42 AM, Andy Pipes <mypipeline@btinternet.com> wrote:
> Hi.
>
> Caveat: I'm just learning Ruby coming from some basic PHP programming.
>
> In the following I am aiming to peer into two tab-separated files with
> some vegetable facts on them. In the first 'column' of each file there
> are vegetable names, followed by the data. However, whilst some of the
> vegetables have the same name, others do not. My ultimate aim is to take
> the contents of each of these files, and merge them into a master file,
> and for those vegetables that have data in both files to merge the data.
>
> So a line from file 1 might read:
>
> Watermelon 60-80 4-10
>
> and one file two:
>
> Watermelon 1/2oz. 34 12-26 24-48
>
> and in the masterfile I would want:
>
> Watermelon 60-80 4-10 1/2oz. 34 12-26 24-48.
>
> I have been trying unsuccessfully for the past two days to do this so
> any help is greatly appreciated!!! :)
>
> Here's some sample code:
>
>
> File.foreach("vegetables.txt") do |line|
>    name, temp, germ_days = line.split /\t/
>    #split min and max germination temps
>    if temp =~ /-/
>      temp_min, temp_max = temp.split /-/
>    else temp_min = temp and temp_max = temp
>    end
>    # split the min and max germ days
>    if germ_days =~ /-/
>      germ_days_min, germ_days_max = germ_days.split /-/
>    else germ_days_min = germ_days and germ_days_max = germ_days
>    end
>
>    # now iterate over the other table
>    File.foreach("vegetables2.txt") do |l|
>      name2, crop_yield, space_between_rows, space_between_plants,
> days_to_harvest = l.split /\t/
>      #split min and max space between rows
>      if space_between_rows =~ /-/
>        space_between_rows_min, space_between_rows_max =
> space_between_rows.split /-/
>      else
>        space_between_rows_min = space_between_rows and
> space_between_rows_max = space_between_rows
>      end
>      # split the min and max space between plants
>      if space_between_plants =~ /-/
>        space_between_plants_min, space_between_plants_max =
> space_between_plants.split /-/
>      else
>        space_between_plants_min = space_between_plants and
> space_between_plants_max = space_between_plants
>      end
>      # split the min and max days to harvest
>      if days_to_harvest =~ /-/
>        days_to_harvest_min, days_to_harvest_max = days_to_harvest.split
> /-/
>      else
>        days_to_harvest_min = days_to_harvest and days_to_harvest_max =
> days_to_harvest
>      end
>      if name2 == name
>        veggies =  {
>            :name => name2,
>            :crop_yield => crop_yield,
>            :temp_min => temp_min,
>            :temp_max => temp_max,
>            :germ_days_min => germ_days_min,
>            :germ_days_max => germ_days_max,
>            :space_between_plants_min => space_between_plants_min,
>            :space_between_plants_max => space_between_plants_max,
>            :space_between_rows_min => space_between_rows_min,
>            :space_between_rows_max => space_between_rows_min,
>            :days_to_harvest_min => days_to_harvest_min,
>            :days_to_harvest_max => days_to_harvest_max
>        }
>      end
>
> puts veggies
>
> end
> end
>
> If I run this, I get local variable not found errors; I've tried a lot
> of variations, with no luck. I'm new to OO, and think that maybe I'm
> just 'not getting it' in this case.
>
> Can anyone help? Thanks in advance.
>
> Andy

For scope, you must establish for the interpreter that these variables
exist outside of the File.foreach blocks.

my_var = ""
File.foreach {|line| #do_something_with_my_var}


Personally, I might try using ranges (needs cleaning up)...

#add method to range for building from
# a string like "1-10"
class Range
  def self.[](str)
    begin
      a = str.split(/-/)
      a[1] ||= [0]
      new(*(a.map {|i| Integer(i)})) rescue str
    end
  end
end

#just a method to split and change to ranges
def collate_veggie str
  str.chomp.split(/\t/).map! {|elem| Range[elem]}
end

#first set of data
veggies1 = {}
keys1 = :temp, :germ_days
File.foreach('veggies1.txt' ) do |line|
  values = collate_veggie line
  veggies1[values.shift] = keys1.zip values
end

#second set of data
veggies2 = {}
keys2 = :crop_yield, :row_space, :plant_space, :harvest_days
File.foreach('veggies2.txt') do |line|
  values = collate_veggie line
  veggies2[values.shift] = keys2.zip values
end

#merge the two
veggies = {}
veggies1.each_key {|k| veggies[k] = Hash[*(veggies1[k] | veggies2[k]).flatten]}

#use Range methods for min and max
p h
p h["Watermelon"][:germ_days].min
p h["JuicyVeggie"][:plant_space].max


just a thought,
Todd