将fastq信息复制到新fastq文件中

Question

我正在尝试写一段代码，这段代码会打开一个fasta文件，从另一个fastq文件中提取读取名称（标题）、序列（seq）和质量分数（qual），但只有当这些信息在fasta文件中找到时，才会提取，并把这些fastq的信息写入一个新的fastq文件。不过，我在写这最后一步的时候遇到了困难（我在代码中用粗体标出了我遇到问题的地方）。有没有人知道怎么写这一部分，或者我可以在哪里找到关于如何在python中输入这些内容的信息？

到目前为止，我有：

from sys import argv
from Bio.SeqIO.QualityIO import FastqGeneralIterator

script, merged_seqs, raw_seqs = argv
merged_from_raw = "merged_only.fastq"

merged_names = set() 
for line in open(merged_seqs): 
        if line[0] == ">":
                read_name = line.split()[0][1:] 
                merged_names.add(read_name) 

raw_fastq = raw_seqs

temp_handle = open(merged_from_raw, "w") 
for title, seq, qual in FastqGeneralIterator(open(raw_fastq)) :
        if title in merged_names:
                **handle.write() #this is where I don't know how to write what I need in python**

Answer 1

除非你有特别的理由自己去实现文件解析，否则使用SeqIO解析器来处理你的输入和输出文件会更好。你可以试试下面这样的代码（注意：我之前没有用过Bio库，也没有测试过这段代码）：

from sys import argv
from Bio import SeqIO

output_filename = 'merged_only.fastq'
merged_seqs, raw_seqs = argv[1:2]

# Get fasta iterator, and read source fastq file into a dict-like object
merged_names = SeqIO.parse(merged_seqs, 'fasta')
source_seqs = SeqIO.index(raw_seqs, 'fastq')

filtered_seqs = (source_seqs[record.id] for record in merged_names if record.id in source_seqs)
SeqIO.write(filtered_seqs, output_filename, 'fastq')