CODEWITHSUNDEEP
ruby
Kyle Kaitan
Kyle Kaitan

Reputation: 1779

Boolean comparison of array of strings in Ruby

I've got an array in Ruby that essentially represents a square boolean matrix. Dots represent zeroes, while any other character represents ones. Example:

irb(main):044:0> g
=> [".b", "m."] # This grid has two '1' values and two '0' values.

I'd like to perform a specified logical operation (say, OR) on this array with another similar array to get a third result. For example, if h is ["q.", "r."], then something akin to g.perform_or(h) should yield a new array ["qb", "r."]. (The choice of r to represent the result of 'm' || 'r' is arbitrary and not relevant; any other non-'.' character can be there.)

How might I do this?

Edit: I made an error in my example. Apologies!

Upvotes: 0

Views: 513

Answers (2)

Jörg W Mittag
Jörg W Mittag

Reputation: 369478

Man, this one has been gathering dust on my disk for a loong time:

class String
  def to_bool; return chars.map {|c| if c == '.' then false else c end } end
  def from_bool; return self end
end

class TrueClass;  def from_bool; return 't' end end
class FalseClass; def from_bool; return '.' end end

class Array
  def to_bool;   map(&:to_bool) end
  def from_bool; map {|row| row.map(&:from_bool).join} end

  def |(other)
    to_bool.zip(other.to_bool).inject([]) {|row, (l, r)|
      row << l.zip(r).inject([]) {|col, (l, r)|
        col << (l || r).from_bool
      }
    }
  end

  def &(other)
    to_bool.zip(other.to_bool).inject([]) {|row, (l, r)|
      row << l.zip(r).inject([]) {|col, (l, r)|
        col << (l && r).from_bool
      }
    }
  end
end

Here's a (rather incomplete) testsuite:

require 'test/unit'
class TestLogicMatrix < Test::Unit::TestCase
  def test_to_bool
    assert_equal [['a', false], [false, 'z']], ['a.', '.z'].to_bool
  end
  def test_from_bool
    assert_equal ['a.', 'tz'], [['a', false], [true, 'z']].from_bool
  end
  def test_that_OR_works
    assert_equal ['qb', 'm.'], (['.b', 'm.'] | ['q.', 'r.']).from_bool
  end
  def test_that_AND_works
    assert_equal ['..', 'r.'], (['.b', 'm.'] & ['q.', 'r.']).from_bool
  end
end

Upvotes: 0

glenn mcdonald
glenn mcdonald

Reputation: 15488

For OR:

g.zip(h).map {|gx,hx| (0...gx.size).map {|i| [gx[i..i],hx[i..i]].any? {|cell| cell != "."} ? "x" : "."}.join}

For AND just change the "any?" to "all?".

Upvotes: 6

Related Questions