python class 实现 fasta 文件解析

没有对象怎么办（object）？？？当然是new一个啊

class Sequence(object):
    # 使用__init__对Sequence进行初始化，Sequence对象具有三个属性
    def __init__(self, name, seq, descr=''):
        self.name = name
        self.seq = seq
        self.descr = descr

    # 给Sequence对象定义一个反向互补方法
    def reverse_complement(self):
        RC = {'A':'T','T':'A','C':'G','G':'C','N':'N',
              'a':'t','t':'a','c':'g','g':'c','n':'n'}
        return Sequence(self.name, ''.join([RC[i] for i in self.seq[::-1]]), self.descr)

    # 定义输出到文件的方法，接受文件句柄输入
    def write_to_fasta_file(self, file_handle):
        def _SeqFormat(seq, chara=80):
            tmp = ''
            for i in range(0,len(seq),chara):
                tmp += (seq[i:(i+chara)]+'\n')
            return tmp
        file_handle.write('>{} {}\n'.format(self.name, self.descr))
        file_handle.write('{}'.format(_SeqFormat(self.seq)))

class FastaReader(object):
    def __init__(self, fastafile):
        self.fasta = fastafile

    # 使用__iter__方法实现对fasta文件的循环解析，其中用到yeild构造了生成器
    def __iter__(self):
        with open(self.fasta) as f:
            seq = None
            for line in f:
                if line.startswith( ">" ):
                    if seq:
                        yield Sequence( name, seq, descr )
                    name, sep, descr = line[1:-1].partition(' ')
                    seq = ""
                else:
                    assert seq is not None, "FASTA file does not start with '>'."
                    seq += line[:-1].encode()
        if seq is not None:
            yield Sequence( name, seq, descr )

# example
for i in FastaReader('ref.fa'):
    # 使用
    i.write_to_fasta_file(file_handle)
    i.seq
    i.name
    i.descr

懒癌发作了，就这，，，