Use grep in conjunction with length to get rid of it. 

print for grep length, split '[ACGT]+', "GTGNNTNNG";;
NN
NN

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Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re: Unwanted empty value in array after Splitting a string by BrowserUk
in thread Unwanted empty value in array after Splitting a string by monkfan

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