=＆GT; a.flatten.max_by（安培;：大小）
= GT; ＃MAKKGKPRPDHRPPA​​HNPHYAHDPPPYSQQQPPLQQQNYAQQMHHGGGGGNRQHARPRPSPPSEVSDCVKYSLFLYNCIFWVSMHSS
 

I am trying to get the longest string from an multidimensional array, however it is not working for some reason.

This is what I have:

a = 
["MAKKGKPRPDHRPPAHNPHYAHDPPPYSQQQPPLQQQNYAQQMNRQHARPRPSPPSEVSDCVKYSLFLYNCIFWVSMHSS"],
["MHHGGGGGNRQHARPRPSPPSEVSDCVKYSLFLYNCIFWVSMHSS"], ["MTYINLGVTRTGDLMIGRHRP"],
["MRIYNRVCFQTAGCYLQNLVTTSIQPARVWTY"], ["MAACGLGRVFSAFKVDEMD"], 
["MPSGFVGKRSGFCQFCCSHI"], ["MTYSTAKEGAYPFRNFN"]]

p a.max_by{|v|v}[0]  # => "MTYSTAKEGAYPFRNFN"

Could someone please let me know what I am doing wrong?

=> a.flatten.max_by(&:size)
=> # "MAKKGKPRPDHRPPAHNPHYAHDPPPYSQQQPPLQQQNYAQQMHHGGGGGNRQHARPRPSPPSEVSDCVKYSLFLYNCIFWVSMHSS"