Regex to remove new lines up to a specific character

Question

I have a series of strings in a file of the format:

>HEADER_Text1
Information here, yada yada yada
Some more information here, yada yada yada
Even some more i         


        

Answer 1

As noted in the comments, your best bet is to use an existing FASTA parser. Why not?

Here's how I would join lines based on the leading greater-than:

def joinup(f):
    buf = []
    for line in f:
        if line.startswith('>'):
            if buf:
                yield " ".join(buf)
            yield line.rstrip()
            buf = []
        else:
            buf.append(line.rstrip())
    yield " ".join(buf)

for joined_line in joinup(open("...")):
    # blah blah...