python - 从 FASTA 文本文件在 python 中创建一个列表

Question

我有像这个小例子这样的文本文件:

>ENST00000491024.1|ENSG00000187583.6|OTTHUMG00000040756.4|OTTHUMT00000097942.2|PLEKHN1-003|PLEKHN1|176
SLESSPDAPDHTSETSHSPLYADPYTPPATSHRRVTDVRGLEEFLSAMQSARGPTPSSPLPSVPVSVPASDPRSCSSGPAGPYLLSKKGALQSRAAQRHRGSAKDGGPQPPDAPQLVSSAREGSPEPWLPLTDGRSPRRSRDPGYDHLWDETLSSSHQKCPQLGGPEASGGLVQWI
>ENST00000433179.2|ENSG00000187642.5|OTTHUMG00000040757.3|-|C1orf170-201|C1orf170|696
MPTQDGQLRRPARPPGPRAWMEPRGGGSSQFSSCPGPASSGDQMQRLLQGPAPRPPGEPPGSPKSPGHSTGSQRPPDSPGAPPRSPSRKKRRAVGAKGGGHTGASASAQTGSPLLPAASPETAKLMAKAGQEELGPGPAGAPEPGPRSPVQEDRPGPGLGLSTPVPVTEQGTDQIRTPRRAKLHTVSTTVWEALPDVSRAKSDMAVSTPASEPQPDRDMAVSTPASEPQSDRDMAVSTPASEPQPDTDMAVSTPASEPQPDRDMAVSIPASKPQSDTAVSTPASEPQSSVALSTPISKPQLDTDVAVSTPASKHGLDVALPTAGPVAKLEVASSPPVSEAVPRMTESSGLVSTPVPRADAAGLAWPPTRRAGPDVVEMEAVVSEPSAGAPGCCSGAPALGLTQVPRKKKVRFSVAGPSPNKPGSGQASARPSAPQTATGAHGGPGAWEAVAVGPRPHQPRILKHLPRPPPSAVTRVGPGSSFAVTLPEAYEFFFCDTIEENEEAEAAAAGQDPAGVQWPDMCEFFFPDVGAQRSRRRGSPEPLPRADPVPAPIPGDPVPISIPEVYEHFFFGEDRLEGVLGPAVPLPLQALEPPRSASEGAGPGTPLKPAVVERLHLALRRAGELRGPVPSFAFSQNDMCLVFVAFATWAVRTSDPHTPDAWKTALLANVGTISAIRYFRRQVGQGRRSHSPSPSS
>ENST00000341290.2|ENSG00000187642.5|OTTHUMG00000040757.3|OTTHUMT00000097943.2|C1orf170-001|C1orf170|676
MEPRGGGSSQFSSCPGPASSGDQMQRLLQGPAPRPPGEPPGSPKSPGHSTGSQRPPDSPGAPPRSPSRKKRRAVGAKGGGHTGASASAQTGSPLLPAASPETAKLMAKAGQEELGPGPAGAPEPGPRSPVQEDRPGPGLGLSTPVPVTEQGTDQIRTPRRAKLHTVSTTVWEALPDVSRAKSDMAVSTPASEPQPDRDMAVSTPASEPQSDRDMAVSTPASEPQPDTDMAVSTPASEPQPDRDMAVSIPASKPQSDTAVSTPASEPQSSVALSTPISKPQLDTDVAVSTPASKHGLDVALPTAGPVAKLEVASSPPVSEAVPRMTESSGLVSTPVPRADAAGLAWPPTRRAGPDVVEMEAVVSEPSAGAPGCCSGAPALGLTQVPRKKKVRFSVAGPSPNKPGSGQASARPSAPQTATGAHGGPGAWEAVAVGPRPHQPRILKHLPRPPPSAVTRVGPGSSFAVTLPEAYEFFFCDTIEENEEAEAAAAGQDPAGVQWPDMCEFFFPDVGAQRSRRRGSPEPLPRADPVPAPIPGDPVPISIPEVYEHFFFGEDRLEGVLGPAVPLPLQALEPPRSASEGAGPGTPLKPAVVERLHLALRRAGELRGPVPSFAFSQNDMCLVFVAFATWAVRTSDPHTPDAWKTALLANVGTISAIRYFRRQVGQGRRSHSPSPSS
>ENST00000428771.2|ENSG00000188290.6|OTTHUMG00000040758.2|OTTHUMT00000097945.2|HES4-002|HES4|247
MAADTPGKPSASPMAGAPASASRTPDKPRSAAEHRKVGSRPGVRGATGGREGRGTQPVPDPQSSKPVMEKRRRARINESLAQLKTLILDALRKESSRHSKLEKADILEMTVRHLRSLRRVQVTAALSADPAVLGKYRAGFHECLAEVNRFLAGCEGVPADVRSRLLGHLAACLRQLGPSRRPASLSPAAPAEAPAPEVYAGRPLLPSLGGPFPLLAPPLLPGLTRALPAAPRAGPQGPGGPWRPWLR

这个文件被分成不同的组。每组有 2 个部分。第一部分以 ">" 开始，这部分的元素被 "|" 分割，之后的行是第二部分。我正在尝试从我的文件中用 Python 制作一个列表，其中包含每个组的 ID 部分的第 6 个元素。这是小示例的预期输出:

list = ["PLEKHN1", "C1orf170", "C1orf170", "HES4"]

我试图首先导入到字典中，然后使用以下命令制作一个类似于预期输出的列表:

from itertools import groupby
with open('infile.txt') as f:
    groups = groupby(f, key=lambda x: not x.startswith(">"))
    d = {}
    for k,v in groups:
        if not k:
            key, val = list(v)[0].rstrip(), "".join(map(str.rstrip,next(groups)[1],""))
            d[key] = val

k = d.keys()
res = [el[5:] for s in k for el in s.split('|')]

但它没有返回我要找的东西。你知道怎么解决吗？

Answer 1

因为这些显然是 FASTA 中的蛋白质序列格式，我建议你使用 Biopython ，它将节省您的时间并且比构建您自己的解析器更健壮:

from Bio import SeqIO

lst = [record.description.split('|')[5] for record in SeqIO.parse('in_file.fasta', 'fasta')]

print(lst)
# ['PLEKHN1', 'C1orf170', 'C1orf170', 'HES4']