Given a string s and a number n, find the most frequently occurring n-gram in the string, where the n-grams can begin at any point in the string. This comes up in DNA analysis, where the 3-base reading frame for a codon can begin at any point in the sequence.
So for
s = 'AACTGAACG'
and
n = 3
we get the following n-grams (trigrams):
AAC, ACT, CTG, TGA, GAA, AAC, ACG
Since AAC appears twice, then the answer, hifreq, is AAC. There will always be exactly one highest frequency n-gram.
This problem was originally inspired by a MATLAB Newsgroup discussion.
Solution Stats
Problem Comments
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1 Comment
E Chang
on 22 Oct 2018
It should be noted that spaces should be ignored or else test suites 3 and 5 fail.
Solution Comments
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1 Comment
Ramoflaple
on 28 Jul 2015
good use of 'hankel' function
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2 Comments
Claudio Gelmi
on 28 Feb 2013
Sorry about this, but I got stuck and I want to learn how to do it. After looking at several solutions, I found my mistake and was able to create my own solution :)
Yao-Siang Su
on 8 Dec 2013
What happens if the test suite changed in the future?
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1 Comment
Gwendolyn Fischer
on 11 Dec 2012
This solution is not correct in general, as the way of using hankel here, generates n-1 fake fragments
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1 Comment
Peter Wittenberg
on 31 Mar 2012
Clever usage of the Hankel matrix. I don't automatically think of the Hankel for this application, but it really works well. Thanks - I've learned something
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1 Comment
David Young
on 2 Feb 2012
What's the point of a 'solution' like this? It passes the test suite, but in what way was it interesting for you to write it?
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