我的代码有问题。我正在尝试使用BioPython迭代genbank文件的基因列表。这是它的样子:
class genBank:
gbProtId = str()
gbStart = int()
gbStop = int()
gbStrand = int()
genBankEntries = list()
for seq_record in SeqIO.parse(genBankFile, "genbank"):
for seq_feature in seq_record.features:
genBankEntry = genBank
if seq_feature.type == "CDS":
genBankEntry.gbProtId = seq_feature.qualifiers['protein_id']
genBankEntry.gbStart = seq_feature.location.start # prodigal GFF3 output is 1 based indexing
genBankEntry.gbStop = seq_feature.location.end
genBankEntry.gbStrand = seq_feature.strand
genBankEntries.append(genBankEntry)
它看起来应该可以工作,但是当我运行它时,结果结构genBankEntries
只是genbank文件中基因数量的一个巨大堆栈,但是seq_record.features中的最终值只是每个列表元素:
00 = {type} <class '__main__.genBank'>
gbProtId = {list} ['BAA31840.1']
gbStart = {ExactPosition} 90649
gbStop = {ExactPosition} 91648
gbStrand = {int} 1
...
82 = {type} <class '__main__.genBank'>
gbProtId = {list} ['BAA31840.1']
gbStart = {ExactPosition} 90649
gbStop = {ExactPosition} 91648
gbStrand = {int} 1
这尤其令人困惑,因为两个for循环似乎都能正常工作:
for seq_record in SeqIO.parse(genBankFile, "genbank"):
for seq_feature in seq_record.features:
print(seq_feature)
为什么是这样?
你永远不会创建任何genBank
类的实例。每个循环迭代都在改变genBank
类的类级属性,并且每次都将相同的对象添加到列表中。每次遍历循环都会覆盖前一遍中的值。
对于内循环的第一行,添加括号以调用类型并创建genBank
的实例。它将改为genBankEntry = genBank()
。这为每个循环传递创建了一个新的不同对象。