如何连接以字母开头的行？

Question

I am trying to concatenate lines in a text file into two lists. First list would contain lines starting uppercase letter and the second for lines which start with a '_'. For instance:

_CAA35997.1 unnamed protein product [Bos taurus] MRTPMLLALLALATLCLAGRADAKPGDAESGKGAAFVSKQEGSEVVKRLRRYLDHWLGAPAPYPDPLEPK REVCELNPDCDELADHIGFQEAYRRFYGPV

_CAA42669.1 beta-2-glycoprotein I, partial [Bos taurus] PALVLLLGFLCHVAIAGRTCPKPDELPFSTVVPLKRTYEPGEQIVFSCQPGYVSRGGIRRFTCPLTGLWP INTLKCMPRVCPFAGILENGTVRYTTFEYPNTISFSCHTGFYLKGASSAKCTEEGKWSPDLPVCAPITCP

First list=['MRTPMLLALLALATLCLAGRADAKPGDAESGKGAAFVSKQEGSEVVKRLRRYLDHWLGAPAPYPDPLEPK REVCELNPDCDELADHIGFQEAYRRFYGPV','PALVLLLGFLCHVAIAGRTCPKPDELPFSTVVPLKRTYEPGEQIVFSCQPGYVSRGGIRRFTCPLTGLWPINTLKCMPRVCPFAGILENGTVRYTTFEYPNTISFSCHTGFYLKGASSAKCTEEGKWSPDLPVCAPITCP']

Second list=['_CAA35997.1','_CAA42669.1']

I have tried the following which does not seem to work. I am running into an issue where each new line is stored as a new entry in the first list, and not concatenating the lines into one entry:

for i in seq.text:
  if (i=='_'):
    second_list.append(i)
  else:
    first_list.append(i)

Answer 1

The easiest way is just to do what you're currently doing, and then do str.join() afterwards to "concatenate" the entire list to each other at once, in order:

for i in seq.text:
  if i.startswith('_'):
    second_list.append(i)
    # to more closely resemble the output you put in your question,
    # you might want to only append the part up to the first whitespace:
    # second_list.append(i.split()[0])
  else:
    first_list.append(i)

first_string = ''.join(first_list)
second_string = ''.join(second_list)

Using an empty string as the separator means that they're concatenated directly to each other, with nothing in between. You can also use anything else as a separator - a comma ',' , a space ' ' , a newline '\n' , or any combination depending on what your desired output is.

Answer 2

import re
a_file = open("your_path/test.txt", "r")
list1 = []
list2 = []
for line in a_file:
    if not line.strip(): continue  # skip the empty line
    stripped_line = line.strip()
    line_list = ''.join(stripped_line)
    # To consider '_' in the first list
    #x = re.findall(r"\b_\w+", line_list)
    if (line_list.isupper()): # if (x):
        list1.append(line_list)`
    else:
        list2.append(line_list)