在R中匹配和计数字符串(k-mer of DNA)。

I have a list of strings (DNA sequence) including A,T,C,G. I want to find all matches and insert into table whose columns are all possible combination of those DNA alphabet (4^k; "k" is length of each match - K-mer - and must be specified by user) and rows represent number of matches in sequence in a list. I have a list of strings (DNA sequence) includi