请参阅@georg的最佳答案（我在下面进行了调整）： Split one file into multiple files based on pattern (cut can occur within lines)
我发现这是一个潜在有用的模式，可以根据初始分隔符将文件拆分为多个。 但是，正如评论者所说，它首先创建一个空白文件，其原因尚不清楚。我认为这与我遇到的问题有关。
在我的（笨拙，我不是python master！）改编中，我尝试通过解析分隔符后的行来设置文件名，然后通过调用output = next（fs）生成器打开新的输出文件。
然而，当然，困境是在分隔符之后的行之前不知道域名。我最终得到的文件名与包含的数据不同步。
输入文件包含100多个xml'树'，每个树都以标准
<?xml version='1.0' encoding='UTF-8'?>
后跟一行，其中包含域名
<ns2:domain ... name="atypi.org" ...">
这是我目前的剧本：
#!/usr/bin/python2.7
import re
def files():
n = 0
while n<12 :
n += 1
print "**DEBUG** in generator nameFile=%s n=%d \r" % (nameFile, n)
yield open('/Users/peterf/Google Drive/2015 Projects-Strategy/Domain Admin/RackDomains/%s.part.xml' % nameFile, 'w')
filename='/Users/peterf/Google Drive/2015 Projects-Strategy/Domain Admin/RackspaceListDomain.output.xml'
nameFile=''
pat ='<?xml'
namePat=re.compile('<ns2:domain.+ name="(.+?)".+>')
fs = files()
outfile = next(fs)
with open(filename) as infile:
for line in infile:
m=namePat.search(line)
if m:
nameFile=m.group(1)
print "<---\rin 'if m:' nameFile=%s\r" % (nameFile)
if pat not in line:
# print "\rin 'pat not in line' line=%s\r" % (line)
outfile.write(line)
else:
items = line.split(pat)
outfile.write(items[0])
for item in items[1:]:
print "in 'for item' pre next(fs) nameFile=%s\r" % (nameFile)
outfile = next(fs)
print "in 'for item' post next(fs) nameFile=%s --->\r" % (nameFile)
outfile.write(pat + item)
我的调试列表显示：
**DEBUG** in generator nameFile= n=1
in 'for item' pre next(fs) nameFile=
**DEBUG** in generator nameFile= n=2
in 'for item' post next(fs) nameFile= --->
<---
in 'if m:' nameFile=addressing.com
in 'for item' pre next(fs) nameFile=addressing.com
**DEBUG** in generator nameFile=addressing.com n=3
in 'for item' post next(fs) nameFile=addressing.com --->
<---
in 'if m:' nameFile=alicemcmahon.com
in 'for item' pre next(fs) nameFile=alicemcmahon.com
**DEBUG** in generator nameFile=alicemcmahon.com n=4
in 'for item' post next(fs) nameFile=alicemcmahon.com --->
<---
in 'if m:' nameFile=alphabets.com
in 'for item' pre next(fs) nameFile=alphabets.com
**DEBUG** in generator nameFile=alphabets.com n=5
in 'for item' post next(fs) nameFile=alphabets.com --->
输出目录包含这些文件名，从第一个'yield'的截断名称开始，我猜...
.part.xml (this has data from 'addressing.com')
addressing.com.part.xml
alicemcmahon.com.part.xml
alphabets.com.part.xml
americanletterpress.com.part.xml
americanwoodtype.com.part.xml
amyshoemaker.com.part.xml
archaicrevivalbooks.com.part.xml
archaicrevivalfonts.com.part.xml
archaicrevivalimages.com.part.xml
astroteddies.com.part.xml
我无法弄清楚如何解决这个问题，在我为文件获取适当的名称之前，生成器正在生成输出文件。
以下是输入文件的一些代表性部分：
<?xml version='1.0' encoding='utf-8'?>
<ns2:domain xmlns:ns3="http://www.w3.org/2005/Atom" xmlns:ns2="http://docs.rackspacecloud.com/dns/api/v1.0" xmlns="http://docs.rackspacecloud.com/dns/api/management/v1.0" id="1204245" name="addressing.com" ttl="300" emailAddress="ipadmin@stabletransit.com" updated="2012-10-10T21:33:36Z" created="2009-07-25T15:05:39Z">
<ns2:nameservers>
<ns2:nameserver name="dns1.stabletransit.com" />
<ns2:nameserver name="dns2.stabletransit.com" />
</ns2:nameservers>
<ns2:recordsList totalEntries="5">
<ns2:record id="A-2542579" type="A" name="addressing.com" data="198.101.155.141" ttl="300" updated="2012-10-10T21:33:35Z" created="2010-02-17T05:02:16Z" />
</ns2:recordsList>
</ns2:domain>
<?xml version='1.0' encoding='UTF-8'?>
<ns2:domain xmlns:ns3="http://www.w3.org/2005/Atom" xmlns:ns2="http://docs.rackspacecloud.com/dns/api/v1.0" xmlns="http://docs.rackspacecloud.com/dns/api/management/v1.0" id="2776403" name="alicemcmahon.com" ttl="300" emailAddress="ipadmin@stabletransit.com" updated="2013-10-21T16:43:17Z" created="2011-05-01T03:01:51Z">
<ns2:nameservers>
<ns2:nameserver name="dns1.stabletransit.com" />
<ns2:nameserver name="dns2.stabletransit.com" />
</ns2:nameservers>
<ns2:recordsList totalEntries="10">
<ns2:record id="A-6895108" type="A" name="alicemcmahon.com" data="216.185.152.144" ttl="300" updated="2013-10-21T16:43:17Z" created="2011-05-01T03:01:51Z" />
</ns2:recordsList>
</ns2:domain>
<?xml version='1.0' encoding='UTF-8'?>
<ns2:domain xmlns:ns3="http://www.w3.org/2005/Atom" xmlns:ns2="http://docs.rackspacecloud.com/dns/api/v1.0" xmlns="http://docs.rackspacecloud.com/dns/api/management/v1.0" id="1204247" name="americanletterpress.com" ttl="300" emailAddress="ipadmin@stabletransit.com" updated="2012-10-10T21:33:37Z" created="2009-07-25T15:05:41Z">
<ns2:nameservers>
<ns2:nameserver name="dns1.stabletransit.com" />
<ns2:nameserver name="dns2.stabletransit.com" />
</ns2:nameservers>
<ns2:recordsList totalEntries="5">
<ns2:record id="A-2542581" type="A" name="americanletterpress.com" data="198.101.155.141" ttl="300" updated="2012-10-10T21:33:36Z" created="2010-02-17T05:02:16Z" />
</ns2:recordsList>
</ns2:domain>
<?xml version='1.0' encoding='UTF-8'?>
<ns2:domain xmlns:ns3="http://www.w3.org/2005/Atom" xmlns:ns2="http://docs.rackspacecloud.com/dns/api/v1.0" xmlns="http://docs.rackspacecloud.com/dns/api/management/v1.0" id="1204249" name="americanwoodtype.com" ttl="300" emailAddress="ipadmin@stabletransit.com" updated="2012-10-10T21:33:38Z" created="2009-07-25T15:05:42Z">
<ns2:nameservers>
<ns2:nameserver name="dns1.stabletransit.com" />
<ns2:nameserver name="dns2.stabletransit.com" />
</ns2:nameservers>
<ns2:recordsList totalEntries="5">
<ns2:record id="A-2542583" type="A" name="americanwoodtype.com" data="198.101.155.141" ttl="300" updated="2012-10-10T21:33:37Z" created="2010-02-17T05:02:16Z" />
</ns2:recordsList>
</ns2:domain>
答案 0 :(得分：1)
您要求生成器在一开始就生成输出文件：
nameFile=''
# ...
outfile = next(fs)
那是你的空白文件名。推迟调用next(fs)，直到您拥有nameFile的值，而不是之前。
您可以在编写之前设置outfile = None并测试None：
if pat not in line:
if outfile is not None:
outfile.write(line)
else:
items = line.split(pat)
if outfile is not None:
outfile.write(items[0])
如果您需要在找到第一个文件名之前处理行，请将这些行存储在缓冲区中，并在首次创建新文件时清除缓冲区。
并不是说我认为你应该使用生成器，你真的使用一个过于复杂的东西。只需在循环中直接创建新的文件对象，就会更加清晰。
如果您要做的就是拆分文件，请使用缓冲区，直到您有文件名：
buffer = []
out_name = '/Users/peterf/Google Drive/2015 Projects-Strategy/Domain Admin/RackDomains/%s.part.xml'
outfile = None
with open(filename) as infile:
for line in infile:
# look for a filename to write to if we don't have one yet
if outfile is None:
match = namePat.search(line)
if match:
# New filename, open a file object
outfile = open(out_name % match.group(1), 'w')
# clear out the buffer, we'll write directly to
# the file after this.
outfile.writelines(buffer)
buffer = []
if '<?xml' in line:
# new XML doc, close off the previous one
if outfile is not None:
outfile.close()
outfile = None
# line handling
if outfile is None:
buffer.append(line)
else:
outfile.write(line)
if outfile is not None:
outfile.close()
# All lines processed, if there is a buffer left, then we have unhandled lines
if buffer:
print('There were trailing lines without a name')
print(*buffer, sep='')