我有一个类,它读取特定格式的文件。这些文件的大小往往大于8Gb,因此通常会被压缩。在读取文件时,我想捕获文件未被压缩的错误,但except IOError:
和except:
都不会这样做,出于某种原因,我不明白。
文件 VCF.py 中一起定义了几个类,但有问题的类是vcfReader()
。实例化对象的文件位于 test.py 之下,最后是Traceback。
任何人都有任何想法,为什么它不起作用?
VCF.py
import gzip
import sys
class Call():
'''
Class to handle the sample genotypes and associated information
'''
def __init__(self,site,sample,format,data):
#do stuff here#
class Variant():
'''
Class for a single row from a VCF file.
'''
def __init__(self, entry, samples):
#do other stuff here
class vcfReader():
'''
read a compressed vcf file ignoring the meta-information, but parsing the header for sample names
'''
def __init__(self, file):
try:
self.vcfFile = gzip.open(file, 'rb')
except IOError:
print "Not a gzipped file"
sys.exit()
self.samples = self.readHeader()
def readHeader(self):
line = self.vcfFile.next()
while line.startswith('#'):
if line[1]!='#':
#lines that start with ##, i.e. meta tags are ignored. Header line starting with '#', sample names are extracted.
return line.rstrip().rsplit('\t')[9:]
else:
line = self.vcfFile.next()
def __iter__(self):
return self
def next(self):
row = self.vcfFile.next()
return Variant(row, self.samples)
然后 test.py
import VCF
from collections import Counter
if __name__=='__main__':
vcfreader = VCF.vcfReader('all_samples.vcf')
filters = []
for i in vcfreader:
filters.extend(i.FILTERS)
filters = Counter(filters)
for k,v in filters.iteritems():
print "{0}: {1}".format(k,v)
这是追溯:
Traceback (most recent call last):
File "C:\Users\Davy\Documents\Programming\VCF_stuff\src\test.py", line 10, in <module>
vcfreader = VCF.vcfReader('all_samples.vcf')
File "C:\Users\Davy\Documents\Programming\VCF_stuff\src\VCF.py", line 95, in __init__
self.samples = self.readHeader()
File "C:\Users\Davy\Documents\Programming\VCF_stuff\src\VCF.py", line 98, in readHeader
line = self.vcfFile.next()
File "C:\Python27\lib\gzip.py", line 450, in readline
c = self.read(readsize)
File "C:\Python27\lib\gzip.py", line 256, in read
self._read(readsize)
File "C:\Python27\lib\gzip.py", line 291, in _read
self._read_gzip_header()
File "C:\Python27\lib\gzip.py", line 185, in _read_gzip_header
raise IOError, 'Not a gzipped file'
IOError: Not a gzipped file
答案 0 :(得分:4)
except
阻止未捕获异常的原因是它发生在try
块之外:
def __init__(self, file):
try:
self.vcfFile = gzip.open(file, 'rb')
except IOError:
print "Not a gzipped file"
sys.exit()
self.samples = self.readHeader() # <<<<<<<< exception is raised here