On Aug 7, 2009, at 11:05 AM, Nik wrote: > Thanks Rob, in line 6 (where #!/usr/bin/ruby -w is line 1) where > results[-1]<<element, is there a check to verify that the element's > cue is true and henceforth start a new and empty array?
No, but lines 7..9 do and line 11 discards the empty array when the last element was a cutoff (element[:cue] in this case) and was not needed to hold other elements. -Rob > On Aug 6, 6:32 pm, Rob Biedenharn <[email protected]> wrote: >> On Aug 6, 2009, at 3:22 PM, Nik wrote: >> >>> Hello, I have this big array of hashes: >>> A =[ h0, h1, h2, ..., hn] >>> some hi's' :cue key is true, others' is false. >>> e.g., >>> h1[:cue] = false >>> h2[:cue] = false >>> h3[:cue] = true >>> h4[:cue] = false >>> h5[:cue] = true >>> ... >>> hn[:cue] = ... >> >>> Again, these hashes are in an array, A. >> >>> Now, I'd like to group them into smaller arrays whose last item >>> has a >>> true cue >>> so >>> A' = [ [h1, h2, h3], [h4, h5], ... , [...] ] >> >>> Is there a built-in method to cook this up? >>> If not, what combination of methods might you think would work most >>> efficiently? >> >>> Thank You >> >> Well, this seems to be a tasty dish. I took some liberty with your >> minimal spec, but you should see the first test for the usage that >> maps to your example. >> >> #!/usr/bin/ruby -w >> class Array >> def split_when >> result = [[]] >> each do |element| >> result[-1] << element >> if block_given? ? yield(element) : element >> result << [] >> end >> end >> result.pop if result.last.empty? >> result >> end >> end >> >> if File.expand_path($0) == File.expand_path(__FILE__) >> require 'test/unit' >> class SplitWhenTest < Test::Unit::TestCase >> def setup >> h1 = { :cue => false } >> h2 = { :cue => false } >> h3 = { :cue => true } >> h4 = { :cue => false } >> h5 = { :cue => true } >> @ary = [ h1, h2, h3, h4, h5 ] >> @expected = [ [h1, h2, h3], [h4, h5] ] >> end >> >> def test_example_from_email >> assert_equal @expected, @ary.split_when {|e| e[:cue]} >> end >> >> def test_simple >> original = [ false, true, false, false, true, true, false, >> true, false, true, false ] >> expected = [[false, true],[false, false, true],[true],[false, >> true],[false, true],[false]] >> assert_equal expected, original.split_when, "no block" >> assert_equal expected, original.split_when {|e|e}, "simple >> block" >> end >> end >> end >> __END__ >> >> :code/ruby $ ./array_split_when.rb >> Loaded suite ./array_split_when >> Started >> .. >> Finished in 0.000585 seconds. >> >> 2 tests, 3 assertions, 0 failures, 0 errors >> >> -Rob Rob Biedenharn http://agileconsultingllc.com [email protected] --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
