Re: Need help capturing output of re.search
On Jun 27, 8:31 am, [EMAIL PROTECTED] wrote:
Hi -
I need help capturing the output of a RegEx search.
I dont understand why this conditional fails.
Here is the code:
#= start snip
==
#!/usr/local/bin/python
import os
import re
dirName = '/home/user/bin/logs'
os.chdir(dirName)
files = os.listdir(dirName)
for myFile in files:
#print 'checking ...', myFile
reCheck = ''
reCheck = re.search(r'\bCC_', myFile)
#print 'reCheck = ', '=', reCheck, '='
if reCheck == None:
print myFile, ' . does not qualify'
else:
print ' ', myFile, 'qualifies...', reCheck
#= end snip
==
The problem is that reCheck never == None.
So all of the files qualify. My understanding of the
re.search (re.search(r'\bCC_', myFile)) is ...
1) give me only files that start with a word boundary (\b)
2) followed by a (CC_)
3) in myFile
Why doesn't the output of the re.search load reCheck with valid data?
(like None)
Because None is not valid data in this case. re.search returns
None or a MatchObject instance.
type(None)
type 'NoneType'
type(None)
type 'str'
None == None
False
You may like to read this: http://www.amk.ca/python/howto/regex/
If you want to check for strings that start with some condition, you
need re.match, not re.search.
You don't need the '\b'; re.match(r'CC_', filename) would do the job.
But then so would filename.startswith('CC_')
HTH,
John
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Re: Need help capturing output of re.search
You may like to read this: http://www.amk.ca/python/howto/regex/ This is a good resource. Thank you. Someone else pointed out that I needed to change the if reCheck == None: to if reCheck == None: # removed the s This worked great! Thanks! --JM -- http://mail.python.org/mailman/listinfo/python-list
Re: Need help capturing output of re.search
On Jun 27, 10:01 am, [EMAIL PROTECTED] wrote: You may like to read this:http://www.amk.ca/python/howto/regex/ This is a good resource. Thank you. Someone else pointed out that I needed to change the if reCheck == None: to if reCheck == None: # removed the s Somebody else should indeed remain anonymous if they told you that. Use if reCheck is None: or even better: if not reCheck: It's not obvious from your response if you got these points: (1) re.match, not re.search (2) filename.startswith does your job simply and more understandably -- http://mail.python.org/mailman/listinfo/python-list
Re: Need help capturing output of re.search
On Jun 26, 5:12 pm, John Machin [EMAIL PROTECTED] wrote:
On Jun 27, 10:01 am, [EMAIL PROTECTED] wrote:
You may like to read this:http://www.amk.ca/python/howto/regex/
This is a good resource. Thank you.
Someone else pointed out that I needed to change the
if reCheck == None:
to
if reCheck == None: # removed the s
Somebody else should indeed remain anonymous if they told you that.
Use
if reCheck is None:
or even better:
if not reCheck:
It's not obvious from your response if you got these points:
(1) re.match, not re.search
(2) filename.startswith does your job simply and more understandably
Understood. I replaced re.search with re.match (although both work)
can filename.startswith be used in a conditional? ala:
if filename.startswith('CC_'):
processtheFile()
Thanks for the great help!
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Re: Need help capturing output of re.search
On Jun 27, 10:45 am, [EMAIL PROTECTED] wrote:
On Jun 26, 5:12 pm, John Machin [EMAIL PROTECTED] wrote:
On Jun 27, 10:01 am, [EMAIL PROTECTED] wrote:
You may like to read this:http://www.amk.ca/python/howto/regex/
This is a good resource. Thank you.
Someone else pointed out that I needed to change the
if reCheck == None:
to
if reCheck == None: # removed the s
Somebody else should indeed remain anonymous if they told you that.
Use
if reCheck is None:
or even better:
if not reCheck:
It's not obvious from your response if you got these points:
(1) re.match, not re.search
(2) filename.startswith does your job simply and more understandably
Understood. I replaced re.search with re.match (although both work)
Not so. Consider a filename that starts with some non-alphanumeric
characters followed by CC_ e.g. ---CC_foo. re.search will score a
hit but re.match won't. It's quite simple: if you want hits only at
the beginning of the string, use re.match. Please don't say I don't
have any filenames like that, so it doesn't matter ... it's like
saying They couldn't hit an elephant at this distance.
can filename.startswith be used in a conditional? ala:
if filename.startswith('CC_'):
processtheFile()
Of course. *Any* expression can be used in a condition. This one
returns True or False -- a prime candidate for such use. Why are you
asking?
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