Display data in columns not rows using Ruby on Rails

Question

I would like to display data in Columns rather than Rows in my web page.

What is the most efficient way to do this using Ruby on Rails?

Many thanks for your

Answer 1

Here's my solution. It takes an array, say ["a", "b", "c", "d"] and converts it into this array: [["a", "b"], ["c"], ["d"]] which is then easy to use to display data in columns.

def categories_in_columns(categories, number_of_groups=3)
  groups = []
  elements_per_column       = categories.size / number_of_groups
  extra_elements            = categories.size % number_of_groups
  has_extra_elements        = (extra_elements > 0 ? 1 : 0)

  0.upto(number_of_groups-1).each do |i|
    groups[i] = []
    while groups[i].size < (elements_per_column + has_extra_elements)
      groups[i] << categories.shift
      extra_elements -= 1 if groups[i].size > elements_per_column
    end
    has_extra_elements = 0 if extra_elements == 0
    groups[i].compact!
  end
  groups.delete_if { |i| i.empty? }
end

And specs for it:

it "arranges categories into columns" do
  categories_in_columns(["a", "b", "c", "d", "e"]).should == [["a", "b"], ["c", "d"], ["e"]]
  categories_in_columns(["a", "b", "c", "d"]     ).should == [["a", "b"], ["c"], ["d"]]
  categories_in_columns(["a", "b", "c"]          ).should == [["a"], ["b"], ["c"]]
  categories_in_columns(["a", "b"]               ).should == [["a"], ["b"]]
  categories_in_columns(["a"]                    ).should == [["a"]]
end