irb(main):036:0> r.as_data_frame({'x' => [1,2,3], 'row.names' => ['a','b','c']})=> {"c(1,
2, 3)"=>[1, 2, 3]}
irb(main):037:0> r.as_data_frame({'x' => [1,2,3], 'row_names' => ['a','b','c']})TypeError: can't modify frozen
string
        from /usr/local/lib/ruby/site_ruby/1.8/rsruby.rb:254:in `gsub!'
        from /usr/local/lib/ruby/site_ruby/1.8/rsruby.rb:254:in `convert_method_name'
        from /usr/local/lib/ruby/site_ruby/1.8/rsruby.rb:218:in `method_missing'        from (irb):37
        from :0
Need to go over 'as.data.frame' to make sure it returns what it should.