#!/usr/bin/ruby -w

require 'csv'

old_table = CSV.open('file.csv','r')

index = [{}, {}, {}, {}, {}] # create one index hash for each column
multi_key_index = {}

old_table.each do |row|
  row.each_with_index do |column,col_num|
    (index[col_num][column] ||= []) << row
  end
  (multi_key_index[row[1] + row[2]] ||= []) << row
end


================
input format for CSV
* only three options for column 0
* each column 0 has two other corresponding rows, in this case the last 3 rows make up a set that needs to be extracted and reformatted.
* every line comes in a set of 3 (although only one set is show here)
* need to find every corresponding orange and banana row for every apple row that is found

"apple","John","qwerty",4,7
"banana","Jane","qwerty",2,7
"apple","Rachel","zxcv",8,3
"apple","Bob","asdf",5,4
"orange","Bob","asdf",4,6
"banana","Bob","asdf",5,9

================
output format for CSV -- need to

Columns correspond to "apple","banana","orange",name,asdf (the numbers are from column[3])

5,2,4,"Bob","asdf"