Question

I am trying to design a parser for FASTA files (without using biopython) and am having problems in the following area:
I have a list of DNA sequences such as [‘AAACCCGAU’, ‘AUUCCCCCCGGA’, ‘AACCCGGUU’, ‘AAACCCCUU’] etc.. named sequence_lines2.
My target program is:
If the element in the list has any multiple of 60 characters, join it to the next element.
This way I can remove the line breaks in FASTA files. The code I have written looks like this:

for el in sequence_lines2:
    if len(el) == 60:
        sequence_lines3 = "".join(el)

How can I make this work? And how to achieve the multiples of 60?
Thanks in advance!

—-Edit—-
If anyone’s interesting in joining elements, have a look here!.

Answer 1

Try with this one liner :

result = "".join([el for el in sequence_lines2 if not len(el) % 60])

The len(el) % 60 computes the modulo of length with 60 and if the result is 0, this is a multiple of 60.