From: Jonathan Rochkind <rochkind@...>
Date: 2011-01-14T02:55:04+09:00
Subject: Hash#select, different than documented?

The documentation at:
http://www.ruby-doc.org/core/classes/Hash.html#M000750

Says that Hash#select does this:

Returns a new hash consisting of entries for which the block returns
true.

If no block is given, an enumerator is returned instead.

   h = { "a" => 100, "b" => 200, "c" => 300 }
   h.select {|k,v| k > "a"}  #=> {"b" => 200, "c" => 300}
   h.select {|k,v| v < 200}  #=> {"a" => 100}

***

However, that is not the behavior I am seeing in my ruby 1.8.6.  Is that
documentation for a later version of ruby, in which this behavior
changed? Or is the documentation just wrong?

I instead get an array of pairs returned. From irb:

irb(main):008:0> h = { "a" => 100, "b" => 200, "c" => 300 }
=> {"a"=>100, "b"=>200, "c"=>300}
irb(main):009:0> h.select {|k,v| k > "a"}  #=> {"b" => 200, "c" => 300}
=> [["b", 200], ["c", 300]]
irb(main):010:0> h.select {|k,v| v < 200}  #=> {"a" => 100}
=> [["a", 100]]



Is there any other search behavior implemented on Hash I could be using
instead, with more convenient behavior for finding hash subsets, and/or
finding hash keys whose values are matched by a certain block?

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