From: Joel Pearson <lists@...>
Date: 2013-02-04T07:43:30+09:00
Subject: Re: Select "columns" from multidimensional array?

I decided to try and build on the Array class as I don't really 
understand Matrices yet. I've added a few handy methods. The hidden Bang 
stuff is justified, I think, as this class is intended to mimic Excel's 
layout.

I'll add more useful bits as I come up with them, this is just an 
experiment at the moment.

class Excel_Sheet<Array

  def initialize( val=[] )
    fail ArgumentError, 'Must be multidimensional array' unless 
val[0].class == Array || val.empty?
    super( val )
  end

  def columns
    ensure_shape
    self[0].length
  end

  def rows
    self.length
  end

  def ensure_shape
    max_size = self.max_by(&:length).length
    self.map! { |ar| ar.length == max_size ? ar : ar + Array.new( 
max_size - ar.length, nil) }
  end

  def get_cols( headers )
    ensure_shape
    self.transpose.select { |header,_| headers.include?(header) 
}.sort_by { |header,_| headers.index(header) || headers.length 
}.transpose
  end

  def get_cols!( headers )
    self.replace get_cols
  end

  def to_s
    self.map { |ar| ar.map { |el| "#{el}".strip.gsub( /\s/, ' ' ) }.join 
"\t" }.join "\n"
  end

end

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