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In memory representation and manipulation of tabular data. Useful for powering all kinds of charts and exports.

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Octocat-spinner-32 lib
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Octocat-spinner-32 data_table.gemspec
README.rdoc

data_table

In memory representation and manipulation of tabular data. Useful for powering all kinds of charts and exports.

class OrderPosition

  attr_accessor :articlenum
  attr_accessor :name
  attr_accessor :ordered
  attr_accessor :group
  attr_accessor :quantity
  attr_accessor :price

  def initialize(articlenum, name, group, ordered, quantity, price)
    @articlenum = articlenum
    @name = name
    @group = group
    @ordered = ordered
    @quantity = quantity
    @price = price
  end

end

order_positions = [
  OrderPosition.new "23423424", "R2D1", "AA", Date.new(2009, 10, 4), 1, 1000.0,
  OrderPosition.new "56456345", "R2D2", "AA", Date.new(2009,  9, 4), 1,  100.0,
  OrderPosition.new "42342344", "R2D3", "AA", Date.new(2009,  9, 4), 1,   10.0,
  OrderPosition.new "56757657", "R2D4", "BB", Date.new(2009, 10, 4), 1,  200.0,
  OrderPosition.new "56678799", "R2D5", "BB", Date.new(2009, 10, 4), 1,   20.0
]

# ----------------------------------------
#           DataTable block API
# ----------------------------------------

# order_positions will be available as source inside the block

t = DataTable.new(order_positions) do

  # Variant 1: implicit method lookup

  column :articlenum,    "Articlenum"
  column :name,          "Product Name"
  column :ordered,       "Datum"
  column :group,         "Product Group"

  # Variant 2: explicit transformer function that yields an item of your collection

  column :amount,        "Amount", lambda { |p| p.quantity*p.price }

  # Variant 3: explicit row modification (see build_rows)

  column(:doubled_price, "Doubled Price")
  build_rows(source) do |row, p| # block can be omitted
    row[:doubled_price] = p.price * 2
  end

end

# ----------------------------------------
#      DataTable public method API
# ----------------------------------------

t = DataTable.new

# Variant 1: implicit method lookup

t.column :articlenum,    "Articlenum"
t.column :name,          "Product Name"
t.column :ordered,       "Datum"
t.column :group,         "Product Group"

# Variant 2: explicit transformer function that yields an item of your collection

t.column(:amount,        "Amount", lambda { |p| p.quantity*p.price })

# Variant 3: explicit row modification (see build_rows)

t.column(:doubled_price, "Doubled Price")
t.build_rows(order_positions) do |row, p| # block can be omitted
  row[:doubled_price] = p.price * 2
end

# ----------------------------------------
#                Grouping
# ----------------------------------------

grouped_table = t.group_by(:ordered, {
  :amount        => DataTable::Aggregators::SUM,
  :doubled_price => DataTable::Aggregators::SUM
}, lambda { |x| "#{x.year}-#{x.month}" })

# ----------------------------------------
#                Exporting
# ----------------------------------------

grouped_table.to_csv # defaults to (:col_sep => ",")

Note on Patches/Pull Requests

  • Fork the project.

  • Make your feature addition or bug fix.

  • Add tests for it. This is important so I don't break it in a future version unintentionally.

  • Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)

  • Send me a pull request. Bonus points for topic branches.

Copyright

Copyright © 2010 Michael Aufreiter. See LICENSE for details.

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