Re: help with regex
Peter Otten <__pete...@web.de> writes:
> >>> pattern = re.compile("(\d+)$")
> >>> match = pattern.search( "LINE: 235 : Primary Shelf Number (attempt 1): 1")
> >>> match.group()
> '1'
An alternative way to accomplish the above using the ‘match’ method::
>>> import re
>>> pattern = re.compile("^.*:(? *)(\d+)$")
>>> match = pattern.match("LINE: 235 : Primary Shelf Number (attempt 1): 1")
>>> match.groups()
('1',)
> See
Right. Always refer to the API documentation for the API you're
attempting to use.
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Re: help with regex
James Smith wrote:
> I want the last "1"
> I can't this to work:
>
pattern=re.compile( "(\d+)$" )
match=pattern.match( "LINE: 235 : Primary Shelf Number (attempt 1): 1")
print match.group()
>>> pattern = re.compile("(\d+)$")
>>> match = pattern.search( "LINE: 235 : Primary Shelf Number (attempt 1):
1")
>>> match.group()
'1'
See
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help with regex
I want the last "1" I can't this to work: >>> pattern=re.compile( "(\d+)$" ) >>> match=pattern.match( "LINE: 235 : Primary Shelf Number (attempt 1): 1") >>> print match.group() -- https://mail.python.org/mailman/listinfo/python-list
Re: Help with regex needed
On Tue, 12 Apr 2011 22:11:55 +0300
Yuri Slobodyanyuk wrote:
> Thanks for the insight, while this code will run once a week and
> optimization isn't really a must here, it is
> still a good idea not to leave half-baked code behind me, especially given
> that it will be running on this server for the next 13 years ;)
You don't want to embarrass yourself in 13 years, eh? :-)
> I have one doubt though . Doesn't using the list comprehension here increase
> number of loops per the same string ?
Nope. It just optimizes the code a bit.
> for nnn in [x.split() for x in hhh]:
> My vision here is that after doing the comprehension it would look:
> for nnn in [1st_field,2nd_field,3rd_filed,...,nth_filed]:
for nnn in hhh:
becomes
for nnn in ('a b c', 'd e f', 'g h i'): # loops three times
for nnn in [x.split() for x in hhh]:
becomes
for nnn in [['a','b','c'],['d','e','f'],['g','h','i']: # still three
> ... and therefore would do number of loops equal to number of fields while
> we really need just one ?
The number of loops is still the number of objects (strings) in hhh.
The only difference is that in the former case you need to split the
variable inside the loop causing the production and destruction of an
extra object.
Be careful though. You can optimize your loops by doing too much in
the for statement. You would be hard put to find a case where
optimization is worth more than readability.
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Re: Help with regex needed
Thanks for the insight, while this code will run once a week and
optimization isn't really a must here, it is
still a good idea not to leave half-baked code behind me, especially given
that it will be running on this server for the next 13 years ;)
I have one doubt though . Doesn't using the list comprehension here increase
number of loops per the same string ?
for nnn in [x.split() for x in hhh]:
My vision here is that after doing the comprehension it would look:
for nnn in [1st_field,2nd_field,3rd_filed,...,nth_filed]:
... and therefore would do number of loops equal to number of fields while
we really need just one ?
Thanks
Yuri
On Tue, Apr 12, 2011 at 3:50 PM, D'Arcy J.M. Cain wrote:
> On Tue, 12 Apr 2011 15:06:25 +0300
> Yuri Slobodyanyuk wrote:
> > Thanks everybody , and especially Chris - i used split and it took me 15
> > mins to make it work :)
>
> That's great. One thing though...
>
> > for nnn in hhh:
> > if nnn.split()[2] == str(time_tuple[1]).strip(' \t\n\r') and
> > nnn.split()[4] == str(time_tuple[0]).strip(' \t\n\r') and
> nnn.split()[3]
> > == str(time_tuple[2]).strip(' \t\n\r') :
>
> You are running split() on the same string three times and running
> strip on the same time tuple each time through the loop. I know that
> you shouldn't optimize before testing for bottlenecks but this is just
> egrecious as well as making it more difficult to read. Consider this.
>
> year = str(time_tuple[0]) # strip() not really needed here
> mon = str(time_tuple[1])
> day = str(time_tuple[2])
>
> for nnn in [x.split() for x in hhh]:
>if nnn[2] == mon and nnn[3] = day and nnn[4] = year:
>
> If strip() were needed you could leave off the argument. The default
> is to strip all whitespace from both ends. In fact, read up on locales
> to see why it is a good idea to omit the argument.
>
> --
> D'Arcy J.M. Cain | Democracy is three wolves
> http://www.druid.net/darcy/| and a sheep voting on
> +1 416 425 1212 (DoD#0082)(eNTP) | what's for dinner.
>
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Re: Help with regex needed
On Tue, 12 Apr 2011 15:06:25 +0300
Yuri Slobodyanyuk wrote:
> Thanks everybody , and especially Chris - i used split and it took me 15
> mins to make it work :)
That's great. One thing though...
> for nnn in hhh:
> if nnn.split()[2] == str(time_tuple[1]).strip(' \t\n\r') and
> nnn.split()[4] == str(time_tuple[0]).strip(' \t\n\r') and nnn.split()[3]
> == str(time_tuple[2]).strip(' \t\n\r') :
You are running split() on the same string three times and running
strip on the same time tuple each time through the loop. I know that
you shouldn't optimize before testing for bottlenecks but this is just
egrecious as well as making it more difficult to read. Consider this.
year = str(time_tuple[0]) # strip() not really needed here
mon = str(time_tuple[1])
day = str(time_tuple[2])
for nnn in [x.split() for x in hhh]:
if nnn[2] == mon and nnn[3] = day and nnn[4] = year:
If strip() were needed you could leave off the argument. The default
is to strip all whitespace from both ends. In fact, read up on locales
to see why it is a good idea to omit the argument.
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Re: Help with regex needed
Thanks everybody , and especially Chris - i used split and it took me 15
mins to make it work :)
The final version looks like:
from datetime import datetime, date, time
today_day = datetime.now()
time_tuple= today_day.timetuple()
hhh = open("file_with_data.data",'r')
for nnn in hhh:
if nnn.split()[2] == str(time_tuple[1]).strip(' \t\n\r') and
nnn.split()[4] == str(time_tuple[0]).strip(' \t\n\r') and nnn.split()[3]
== str(time_tuple[2]).strip(' \t\n\r') :
print nnn
Cheers and good day everyone
Yuri
On Tue, Apr 12, 2011 at 8:58 AM, Chris Rebert wrote:
> On Mon, Apr 11, 2011 at 10:20 PM, Yuri Slobodyanyuk
> wrote:
> > Good day everyone,
> > I am trying to make this pretty simple regex to work but got stuck,
> > I'd appreciate your help .
>
> "Some people, when confronted with a problem, think 'I know, I'll use
> regular expressions.' Now they have two problems."
>
>
> > 111 Fri 4 8 2011
> > 2323232 Fri 4 15 2011
> > 4343434 Fri 4 22 2011
> > 8522298 Fri 4 29 2011
> > .
> > 5456678 Fri 10 28 2011
> > 563 Fri 11 4 2011
> > 4141411 Fri 11 11 2011
> > 332 Fri 11 18 2011
>
> There's no need to use regexes to parse such a simple file format.
> Just use str.split() [without any arguments] on each line of the file,
> and do the field equality checks yourself; your code will simpler.
> Relevant docs: http://docs.python.org/library/stdtypes.html#str.split
>
> Cheers,
> Chris
> --
> http://blog.rebertia.com
>
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Re: Help with regex needed
On Mon, Apr 11, 2011 at 10:20 PM, Yuri Slobodyanyuk wrote: > Good day everyone, > I am trying to make this pretty simple regex to work but got stuck, > I'd appreciate your help . "Some people, when confronted with a problem, think 'I know, I'll use regular expressions.' Now they have two problems." > 111 Fri 4 8 2011 > 2323232 Fri 4 15 2011 > 4343434 Fri 4 22 2011 > 8522298 Fri 4 29 2011 > . > 5456678 Fri 10 28 2011 > 563 Fri 11 4 2011 > 4141411 Fri 11 11 2011 > 332 Fri 11 18 2011 There's no need to use regexes to parse such a simple file format. Just use str.split() [without any arguments] on each line of the file, and do the field equality checks yourself; your code will simpler. Relevant docs: http://docs.python.org/library/stdtypes.html#str.split Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex needed
On Mon, Apr 11, 2011 at 10:20 PM, Yuri Slobodyanyuk
wrote:
> Good day everyone,
> I am trying to make this pretty simple regex to work but got stuck,
> I'd appreciate your help .
> Task: Get current date , then read file of format below, find the line that
> matches
> the current date of month,month and year and extract the number from such
> line.
> Here is what I did , but if i run it at 11 April 2011 ...
> - regex pattern_match matches nothing
> - regex pattern_test matches the line "4141411 Fri 11 11 2011" , logical
> as it is the last matching line in year 2011 with the date of 11th.
> My question - why regex pattern_match does not match anything and how to
> make it match the exact line i want.
> Thanks
> Yuri
>
> from datetime import datetime, date, time
> import re
> today_day = datetime.now()
> time_tuple= today_day.timetuple()
> pattern_match = re.compile("([0-9])+ +" + "Fri +" + str(time_tuple[1]) + "
> +" + str(time_tuple[2]) + " +" + str(time_tuple[0]) + " +")
^^
This trailing " +" *requires* that the lines have trailing spaces. Do
they? Such files typically don't, and your example input doesn't
either (although that may be due to email formatting lossage).
Cheers,
Chris
--
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> hhh = open("file_with_data.data",'r')
> pattern_test = re.compile("([0-9]+)" + ".*" + " +" +
> str(time_tuple[2]).strip(' \t\n\r') + " +" + str(time_tuple[0]).strip('
> \t\n\r') )
> for nnn in hhh:
> if (re.search(pattern_test,nnn)):
> print nnn.split()[0]
>
> 111 Fri 4 8 2011
> 2323232 Fri 4 15 2011
> 4343434 Fri 4 22 2011
> 8522298 Fri 4 29 2011
> .
> 5456678 Fri 10 28 2011
> 563 Fri 11 4 2011
> 4141411 Fri 11 11 2011
> 332 Fri 11 18 2011
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Re: Help with regex needed
On Tue, Apr 12, 2011 at 10:50 AM, Yuri Slobodyanyuk
wrote:
> Good day everyone,
> I am trying to make this pretty simple regex to work but got stuck,
> I'd appreciate your help .
> Task: Get current date , then read file of format below, find the line that
> matches
> the current date of month,month and year and extract the number from such
> line.
> Here is what I did , but if i run it at 11 April 2011 ...
> - regex pattern_match matches nothing
> - regex pattern_test matches the line "4141411 Fri 11 11 2011" , logical
> as it is the last matching line in year 2011 with the date of 11th.
> My question - why regex pattern_match does not match anything and how to
> make it match the exact line i want.
> Thanks
> Yuri
Consider using datetime.strptime to parse dates and times. You will
have to strip off the first column since it doesn't look like part of
the date itself.
>
> from datetime import datetime, date, time
> import re
> today_day = datetime.now()
> time_tuple= today_day.timetuple()
> pattern_match = re.compile("([0-9])+ +" + "Fri +" + str(time_tuple[1]) + "
> +" + str(time_tuple[2]) + " +" + str(time_tuple[0]) + " +")
> hhh = open("file_with_data.data",'r')
> pattern_test = re.compile("([0-9]+)" + ".*" + " +" +
> str(time_tuple[2]).strip(' \t\n\r') + " +" + str(time_tuple[0]).strip('
> \t\n\r') )
> for nnn in hhh:
> if (re.search(pattern_test,nnn)):
> print nnn.split()[0]
>
> 111 Fri 4 8 2011
> 2323232 Fri 4 15 2011
> 4343434 Fri 4 22 2011
> 8522298 Fri 4 29 2011
> .
> 5456678 Fri 10 28 2011
> 563 Fri 11 4 2011
> 4141411 Fri 11 11 2011
> 332 Fri 11 18 2011
>
> --
>
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>
>
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Help with regex needed
Good day everyone,
I am trying to make this pretty simple regex to work but got stuck,
I'd appreciate your help .
Task: Get current date , then read file of format below, find the line that
matches
the current date of month,month and year and extract the number from such
line.
Here is what I did , but if i run it at 11 April 2011 ...
- regex pattern_match matches nothing
- regex pattern_test matches the line "4141411 Fri 11 11 2011" , logical
as it is the last matching line in year 2011 with the date of 11th.
My question - why regex pattern_match does not match anything and how to
make it match the exact line i want.
Thanks
Yuri
from datetime import datetime, date, time
import re
today_day = datetime.now()
time_tuple= today_day.timetuple()
pattern_match = re.compile("([0-9])+ +" + "Fri +" + str(time_tuple[1]) + "
+" + str(time_tuple[2]) + " +" + str(time_tuple[0]) + " +")
hhh = open("file_with_data.data",'r')
pattern_test = re.compile("([0-9]+)" + ".*" + " +" +
str(time_tuple[2]).strip(' \t\n\r') + " +" + str(time_tuple[0]).strip('
\t\n\r') )
for nnn in hhh:
if (re.search(pattern_test,nnn)):
print nnn.split()[0]
111 Fri 4 8 2011
2323232 Fri 4 15 2011
4343434 Fri 4 22 2011
8522298 Fri 4 29 2011
.
5456678 Fri 10 28 2011
563 Fri 11 4 2011
4141411 Fri 11 11 2011
332 Fri 11 18 2011
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Re: help with regex matching multiple %e
Thanks,
works great.
matt
On 3/3/2011 10:53 AM, MRAB wrote:
> On 03/03/2011 17:33, maf...@nmsu.edu wrote:
>> Hi,
>>
>> i have a line that looks something like:
>> 2.234e+04 3.456e+02 7.234e+07 1.543e+04: some description
>>
>> I would like to extract all the numbers. From the python website i
>> got the
>> following expression for matching what in c is %e (i.e. scientific
>> format):
>> (see http://docs.python.org/library/re.html)
>> [-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?
>> And when i apply the pattern (using extra parenthesis around the whole
>> expression) it does match the first number in the line.
>>
>> Is there any way to repeat this pattern to get me all the numbers in the
>> line?
>> I though the following might work, but i doesn't:
>> ([-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?){numToRepeat)
>>
> You're forgetting that the numbers are separated by a space.
>
>> Or will i have to split the line first, then iterate and the apply
>> the match?
>>
>> Any help is greatly appreciated.
>>
> Use re.findall to find all the matches.
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Re: help with regex matching multiple %e
On 03/03/2011 17:33, maf...@nmsu.edu wrote:
Hi,
i have a line that looks something like:
2.234e+04 3.456e+02 7.234e+07 1.543e+04: some description
I would like to extract all the numbers. From the python website i got the
following expression for matching what in c is %e (i.e. scientific
format):
(see http://docs.python.org/library/re.html)
[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?
And when i apply the pattern (using extra parenthesis around the whole
expression) it does match the first number in the line.
Is there any way to repeat this pattern to get me all the numbers in the
line?
I though the following might work, but i doesn't:
([-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?){numToRepeat)
You're forgetting that the numbers are separated by a space.
Or will i have to split the line first, then iterate and the apply the match?
Any help is greatly appreciated.
Use re.findall to find all the matches.
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help with regex matching multiple %e
Hi,
i have a line that looks something like:
2.234e+04 3.456e+02 7.234e+07 1.543e+04: some description
I would like to extract all the numbers. From the python website i got the
following expression for matching what in c is %e (i.e. scientific
format):
(see http://docs.python.org/library/re.html)
[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?
And when i apply the pattern (using extra parenthesis around the whole
expression) it does match the first number in the line.
Is there any way to repeat this pattern to get me all the numbers in the
line?
I though the following might work, but i doesn't:
([-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?){numToRepeat)
Or will i have to split the line first, then iterate and the apply the match?
Any help is greatly appreciated.
thanks
matt
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Re: Help with regex search-and-replace (Perl to Python)
Schif Schaf wrote: On Feb 7, 8:57 am, Tim Chase wrote: Steve Holden wrote: Really? Under what circumstances does a simple one-for-one character replacement operation fail? Failure is only defined in the clarified context of what the OP wants :) Replacement operations only fail if the OP's desired output from the above mess doesn't change *all* of the ]/[ characters, but only those with some form of parity (nested or otherwise). But if the OP *does* want all of the ]/[ characters replaced regardless of contextual nature, then yes, replace is a much better solution than regexps. I need to do the usual "pipe text through and do various search/ replace" thing fairly often. The above case of having to replace brackets with braces is only one example. Simple string methods run out of steam pretty quickly and much of my work relies on using regular expressions. Yes, I try to keep focused on simplicity, and often regexes are the simplest solution for my day-to-day needs. Could you post a complex case? It's a kindness to your helpers to simplify your case, but if the simplification doesn't cover the full scope of your problem you can't expect the suggestions to cover it. Frederic -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex search-and-replace (Perl to Python)
On Feb 7, 8:57 am, Tim Chase wrote: > Steve Holden wrote: > > > Really? Under what circumstances does a simple one-for-one character > > replacement operation fail? > > Failure is only defined in the clarified context of what the OP > wants :) Replacement operations only fail if the OP's desired > output from the above mess doesn't change *all* of the ]/[ > characters, but only those with some form of parity (nested or > otherwise). But if the OP *does* want all of the ]/[ characters > replaced regardless of contextual nature, then yes, replace is a > much better solution than regexps. > I need to do the usual "pipe text through and do various search/ replace" thing fairly often. The above case of having to replace brackets with braces is only one example. Simple string methods run out of steam pretty quickly and much of my work relies on using regular expressions. Yes, I try to keep focused on simplicity, and often regexes are the simplest solution for my day-to-day needs. -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex search-and-replace (Perl to Python)
Steve Holden wrote: Tim Chase wrote: And to answer those who are reaching for other non-regex (whether string translations or .replace(), or pyparsing) solutions, it depends on what you want to happen in pathological cases like s = """Dangling closing] with properly [[nested]] and complex [properly [nested] text] and [improperly [nested] text and with some text [straddling lines] and with dangling opening [brackets """ where you'll begin to see the differences. Really? Under what circumstances does a simple one-for-one character replacement operation fail? Failure is only defined in the clarified context of what the OP wants :) Replacement operations only fail if the OP's desired output from the above mess doesn't change *all* of the ]/[ characters, but only those with some form of parity (nested or otherwise). But if the OP *does* want all of the ]/[ characters replaced regardless of contextual nature, then yes, replace is a much better solution than regexps. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex search-and-replace (Perl to Python)
Tim Chase wrote:
> Schif Schaf wrote:
>> On Feb 7, 12:19 am, "Alf P. Steinbach" wrote:
>>> I haven't used regexps in Python before, but what I did was (1) look
>>> in the
>>> documentation,
> [snip]
>>>
>>> import re
>>>
>>> text = (
>>> "Lorem [ipsum] dolor sit amet, consectetur",
>>> "adipisicing elit, sed do eiusmod tempor",
>>> "incididunt ut [labore] et [dolore] magna aliqua."
>>> )
>>>
>>> withbracks = re.compile( r'\[(.+?)\]' )
>>> for line in text:
>>> print( re.sub( withbracks, r'{\1}', line) )
>>>
>>
>> Seems like there's magic happening here. There's the `withbracks`
>> regex that applies itself to `line`. But then when `re.sub()` does the
>> replacement operation, it appears to consult the `withbracks` regex on
>> the most recent match it just had.
>
> I suspect Alf's rustiness with regexps caused him to miss the simpler
> rendition of
>
> print withbacks.sub(r'{\1}', line)
>
> And to answer those who are reaching for other non-regex (whether string
> translations or .replace(), or pyparsing) solutions, it depends on what
> you want to happen in pathological cases like
>
> s = """Dangling closing]
> with properly [[nested]] and
> complex [properly [nested] text]
> and [improperly [nested] text
> and with some text [straddling
> lines] and with
> dangling opening [brackets
> """
> where you'll begin to see the differences.
>
Really? Under what circumstances does a simple one-for-one character
replacement operation fail?
regards
Steve
--
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Re: Help with regex search-and-replace (Perl to Python)
Schif Schaf writes:
> (brackets replaced by braces). I can do that with Perl pretty easily:
>
>
> for (<>) {
> s/\[(.+?)\]/\{$1\}/g;
> print;
> }
>
Just curious, but since this is just transpose, then why not simply
tr/[]/{}/? I.e. why use a regular expression at all for this?
In python you would do this with
for line in text:
print line.replace('[', '{').replace(']', '}')
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Re: Help with regex search-and-replace (Perl to Python)
@ Rocteur CC wrote:
>
> On 07 Feb 2010, at 10:03, Shashwat Anand wrote:
>
>> Here is one simple solution :
>> >>> intext = """Lorem [ipsum] dolor sit amet, consectetur adipisicing
>> elit, sed do eiusmod tempor incididunt ut [labore] et [dolore] magna
>> aliqua."""
>>
>> >>> intext.replace('[', '{').replace(']',
>> '}')
>> 'Lorem {ipsum} dolor sit amet, consectetur adipisicing elit, sed do
>> eiusmod tempor incididunt ut {labore} et {dolore} magna aliqua.'
>>
>> /Some people, when confronted with a problem, think "I know, I’ll use
>> regular expressions." Now they have two problems./ — Jamie Zawinski
>> in comp.lang.emacs.
>
> That is because regular expressions are what we learned in programming
> the shell from sed to awk and ksh and zsh and of course Perl and we've
> read the two books by Jeffrey and much much more!!!
>
> How do we rethink and relearn how we do things and should we ?
>
> What is the solution ?
>
A rigorous focus on programming simplicity.
regards
Steve
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Re: Help with regex search-and-replace (Perl to Python)
Schif Schaf wrote:
On Feb 7, 12:19 am, "Alf P. Steinbach" wrote:
I haven't used regexps in Python before, but what I did was (1) look in the
documentation,
[snip]
import re
text = (
"Lorem [ipsum] dolor sit amet, consectetur",
"adipisicing elit, sed do eiusmod tempor",
"incididunt ut [labore] et [dolore] magna aliqua."
)
withbracks = re.compile( r'\[(.+?)\]' )
for line in text:
print( re.sub( withbracks, r'{\1}', line) )
Seems like there's magic happening here. There's the `withbracks`
regex that applies itself to `line`. But then when `re.sub()` does the
replacement operation, it appears to consult the `withbracks` regex on
the most recent match it just had.
I suspect Alf's rustiness with regexps caused him to miss the
simpler rendition of
print withbacks.sub(r'{\1}', line)
And to answer those who are reaching for other non-regex (whether
string translations or .replace(), or pyparsing) solutions, it
depends on what you want to happen in pathological cases like
s = """Dangling closing]
with properly [[nested]] and
complex [properly [nested] text]
and [improperly [nested] text
and with some text [straddling
lines] and with
dangling opening [brackets
"""
where you'll begin to see the differences.
-tkc
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Re: Help with regex search-and-replace (Perl to Python)
On 07 Feb 2010, at 10:03, Shashwat Anand wrote:
Here is one simple solution :
>>> intext = """Lorem [ipsum] dolor sit amet, consectetur
adipisicing elit, sed do eiusmod tempor incididunt ut [labore] et
[dolore] magna aliqua."""
>>> intext.replace('[', '{').replace(']', '}')
'Lorem {ipsum} dolor sit amet, consectetur adipisicing elit, sed do
eiusmod tempor incididunt ut {labore} et {dolore} magna aliqua.'
Some people, when confronted with a problem, think "I know, I’ll use
regular expressions." Now they have two problems. — Jamie Zawinski
in comp.lang.emacs.
That is because regular expressions are what we learned in programming
the shell from sed to awk and ksh and zsh and of course Perl and we've
read the two books by Jeffrey and much much more!!!
How do we rethink and relearn how we do things and should we ?
What is the solution ?
Jerry--
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Re: Help with regex search-and-replace (Perl to Python)
Here is one simple solution :
>>> intext = """Lorem [ipsum] dolor sit amet, consectetur adipisicing elit,
sed do eiusmod tempor incididunt ut [labore] et [dolore] magna aliqua."""
>>> intext.replace('[', '{').replace(']',
'}')
'Lorem {ipsum} dolor sit amet, consectetur adipisicing elit, sed do eiusmod
tempor incididunt ut {labore} et {dolore} magna aliqua.'
*Some people, when confronted with a problem, think "I know, I’ll use
regular expressions." Now they have two problems.* — Jamie
Zawinskiin comp.lang.emacs.
On Sun, Feb 7, 2010 at 11:15 AM, Schif Schaf wrote:
> On Feb 7, 12:19 am, "Alf P. Steinbach" wrote:
>
> >
> > I haven't used regexps in Python before, but what I did was (1) look in
> the
> > documentation,
>
> Hm. I checked in the repl, running `import re; help(re)` and the docs
> on the `sub()` method didn't say anything about using back-refs in the
> replacement string. Neat feature though.
>
> > (2) check that it worked.
> >
> >
> > import re
> >
> > text = (
> > "Lorem [ipsum] dolor sit amet, consectetur",
> > "adipisicing elit, sed do eiusmod tempor",
> > "incididunt ut [labore] et [dolore] magna aliqua."
> > )
> >
> > withbracks = re.compile( r'\[(.+?)\]' )
> > for line in text:
> > print( re.sub( withbracks, r'{\1}', line) )
> >
> >
>
> Seems like there's magic happening here. There's the `withbracks`
> regex that applies itself to `line`. But then when `re.sub()` does the
> replacement operation, it appears to consult the `withbracks` regex on
> the most recent match it just had.
>
> Thanks.
> --
> http://mail.python.org/mailman/listinfo/python-list
>
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Re: Help with regex search-and-replace (Perl to Python)
On Feb 7, 12:19 am, "Alf P. Steinbach" wrote:
>
> I haven't used regexps in Python before, but what I did was (1) look in the
> documentation,
Hm. I checked in the repl, running `import re; help(re)` and the docs
on the `sub()` method didn't say anything about using back-refs in the
replacement string. Neat feature though.
> (2) check that it worked.
>
>
> import re
>
> text = (
> "Lorem [ipsum] dolor sit amet, consectetur",
> "adipisicing elit, sed do eiusmod tempor",
> "incididunt ut [labore] et [dolore] magna aliqua."
> )
>
> withbracks = re.compile( r'\[(.+?)\]' )
> for line in text:
> print( re.sub( withbracks, r'{\1}', line) )
>
>
Seems like there's magic happening here. There's the `withbracks`
regex that applies itself to `line`. But then when `re.sub()` does the
replacement operation, it appears to consult the `withbracks` regex on
the most recent match it just had.
Thanks.
--
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Re: Help with regex search-and-replace (Perl to Python)
* Schif Schaf:
Hi,
I've got some text that looks like this:
Lorem [ipsum] dolor sit amet, consectetur
adipisicing elit, sed do eiusmod tempor
incididunt ut [labore] et [dolore] magna aliqua.
and I want to make it look like this:
Lorem {ipsum} dolor sit amet, consectetur
adipisicing elit, sed do eiusmod tempor
incididunt ut {labore} et {dolore} magna aliqua.
(brackets replaced by braces). I can do that with Perl pretty easily:
for (<>) {
s/\[(.+?)\]/\{$1\}/g;
print;
}
but am not able to figure out how to do it with Python. I start out
trying something like:
import re, sys
withbracks = re.compile(r'\[(.+?)\]')
for line in sys.stdin:
mat = withbracks.search(line)
if mat:
# Well, this line has at least one.
# Should be able to use withbracks.sub()
# and mat.group() maybe ... ?
line = withbracks.sub('{' + mat.group(0) + '}', line)
# No, that's not working right.
sys.stdout.write(line)
but then am not sure where to go with that.
How would you do it?
I haven't used regexps in Python before, but what I did was (1) look in the
documentation, (2) check that it worked.
import re
text = (
"Lorem [ipsum] dolor sit amet, consectetur",
"adipisicing elit, sed do eiusmod tempor",
"incididunt ut [labore] et [dolore] magna aliqua."
)
withbracks = re.compile( r'\[(.+?)\]' )
for line in text:
print( re.sub( withbracks, r'{\1}', line) )
Python's equivalent of the Perl snippet seems to be the same number of lines,
and more clear. :-)
Cheers & hth.,
- Alf
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Help with regex search-and-replace (Perl to Python)
Hi,
I've got some text that looks like this:
Lorem [ipsum] dolor sit amet, consectetur
adipisicing elit, sed do eiusmod tempor
incididunt ut [labore] et [dolore] magna aliqua.
and I want to make it look like this:
Lorem {ipsum} dolor sit amet, consectetur
adipisicing elit, sed do eiusmod tempor
incididunt ut {labore} et {dolore} magna aliqua.
(brackets replaced by braces). I can do that with Perl pretty easily:
for (<>) {
s/\[(.+?)\]/\{$1\}/g;
print;
}
but am not able to figure out how to do it with Python. I start out
trying something like:
import re, sys
withbracks = re.compile(r'\[(.+?)\]')
for line in sys.stdin:
mat = withbracks.search(line)
if mat:
# Well, this line has at least one.
# Should be able to use withbracks.sub()
# and mat.group() maybe ... ?
line = withbracks.sub('{' + mat.group(0) + '}', line)
# No, that's not working right.
sys.stdout.write(line)
but then am not sure where to go with that.
How would you do it?
Thanks.
--
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Re: Help with regex and optional substring in search string
On Wed, Oct 14, 2009 at 10:30 AM, Zero Piraeus wrote: > '(?:etc)' instead of '(etc)' are non-grouping parentheses (since you > apparently don't care about that bit). Ah yes, thanks. > '[^\]]' instead of '[\w\s]' matches "everything except a closing bracket". I originally had just '[^\]', and I couldn't figure out why it wouldn't work. Maybe I need new glasses. > The '\s*' before the second set of parentheses takes out the leading > whitespace that would otherwise be returned as part of the match. And I want that. The next line of my code is: description = m.group(2).strip() + "\n\n" -- Timur Tabi Linux kernel developer at Freescale -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex and optional substring in search string
: 2009/10/14 Timur Tabi : > Never mind ... I figured it out. The middle block should have been [\w > \s/]* This is fragile - you'll have to keep adding extra characters to match if the input turns out to contain them. -[]z. -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex and optional substring in search string
:
2009/10/14 Timur Tabi :
> I'm having trouble creating a regex pattern that matches a string that
> has an optional substring in it. What I'm looking for is a pattern
> that matches both of these strings:
>
> Subject: [PATCH 08/18] This is the patch name
> Subject: This is the patch name
>
> What I want is to extract the "This is the patch name". I tried this:
>
> m = re.search('Subject:\s*(\[[\w\s]*\])*(.*)', x)
>
> Unfortunately, the second group appears to be too greedy, and returns
> this:
>
print m.group(1)
> None
print m.group(2)
> [PATCH 08/18] Subject line
It's not that the second group is too greedy. The first group isn't
matching what you want it to, because neither \w nor \s match the "/"
inside your brackets. This works for your example input:
>>> import re
>>> pattern = re.compile("Subject:\s*(?:\[[^\]]*\])?\s*(.*)")
>>> for s in (
... "Subject: [PATCH 08/18] This is the patch name",
... "Subject: This is the patch name",
... ):
... re.search(pattern, s).group(1)
...
'This is the patch name'
'This is the patch name'
Going through the changes from your original regex in order:
'(?:etc)' instead of '(etc)' are non-grouping parentheses (since you
apparently don't care about that bit).
'[^\]]' instead of '[\w\s]' matches "everything except a closing bracket".
The '\s*' before the second set of parentheses takes out the leading
whitespace that would otherwise be returned as part of the match.
-[]z.
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Re: Help with regex and optional substring in search string
On Oct 14, 9:51 am, Timur Tabi wrote:
> I'm having trouble creating a regex pattern that matches a string that
> has an optional substring in it. What I'm looking for is a pattern
> that matches both of these strings:
>
> Subject: [PATCH 08/18] This is the patch name
> Subject: This is the patch name
>
> What I want is to extract the "This is the patch name". I tried this:
>
> m = re.search('Subject:\s*(\[[\w\s]*\])*(.*)', x)
Never mind ... I figured it out. The middle block should have been [\w
\s/]*
--
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Help with regex and optional substring in search string
I'm having trouble creating a regex pattern that matches a string that
has an optional substring in it. What I'm looking for is a pattern
that matches both of these strings:
Subject: [PATCH 08/18] This is the patch name
Subject: This is the patch name
What I want is to extract the "This is the patch name". I tried this:
m = re.search('Subject:\s*(\[[\w\s]*\])*(.*)', x)
Unfortunately, the second group appears to be too greedy, and returns
this:
>>> print m.group(1)
None
>>> print m.group(2)
[PATCH 08/18] Subject line
>>>
Can anyone help me? I'd hate to have to use two regex patterns, one
with the [...] and one without.
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Re: Help with regex
On Thu, 06 Aug 2009 17:02:44 +0100, MRAB wrote: > The character class \d is equivalent to [0-9] Not for Unicode, which is the default in 3.x. -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex
On Thu, 06 Aug 2009 14:23:47 -0700, Ethan Furman wrote: >> [0-9]+ allows any number of leading zeros, which is sometimes undesirable. >> Using: >> >> (0|[1-9][0-9]*) >> >> is more robust. > > You make a good point about possibly being undesirable, but I question > the assertion that your solution is /more robust/. If the OP > wants/needs to match numbers even with leading zeroes your /more robust/ > version fails. Well, the OP did say: > The regex should only match the exact above. I suppose that it depends upon the definition of "exact" ;) More seriously: failing to produce an error when one is called for is also a bug. Personally, unless I knew for certain that the rest of the program would handle leading zeros correctly (e.g. *not* interpreting the number as octal), I would try to reject it in the parser. It's usually much easier to determine the cause of an error raised by the parser than if you allow bogus data to propagate deep into the program. -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with regex
On Aug 7, 7:23 am, Ethan Furman wrote:
> Nobody wrote:
> > On Thu, 06 Aug 2009 08:35:57 -0700, Robert Dailey wrote:
>
> >>I'm creating a python script that is going to try to search a text
> >>file for any text that matches my regular expression. The thing it is
> >>looking for is:
>
> >>FILEVERSION #,#,#,#
>
> >>The # symbol represents any number that can be any length 1 or
> >>greater. Example:
>
> >>FILEVERSION 1,45,10082,3
>
> >>The regex should only match the exact above. So far here's what I have
> >>come up with:
>
> >>re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
>
> > [0-9]+ allows any number of leading zeros, which is sometimes undesirable.
> > Using:
>
> > (0|[1-9][0-9]*)
>
> > is more robust.
>
> You make a good point about possibly being undesirable, but I question
> the assertion that your solution is /more robust/. If the OP
> wants/needs to match numbers even with leading zeroes your /more robust/
> version fails.
I'd go further: the OP would probably be better off matching anything
that looked vaguely like an attempt to produce what he wanted e.g.
r"FILEVERSION\s*[0-9,]{3,}" and then taking appropriate action based
on whether that matched a "strictly correct" regex.
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Re: Help with regex
Nobody wrote:
On Thu, 06 Aug 2009 08:35:57 -0700, Robert Dailey wrote:
I'm creating a python script that is going to try to search a text
file for any text that matches my regular expression. The thing it is
looking for is:
FILEVERSION #,#,#,#
The # symbol represents any number that can be any length 1 or
greater. Example:
FILEVERSION 1,45,10082,3
The regex should only match the exact above. So far here's what I have
come up with:
re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
[0-9]+ allows any number of leading zeros, which is sometimes undesirable.
Using:
(0|[1-9][0-9]*)
is more robust.
You make a good point about possibly being undesirable, but I question
the assertion that your solution is /more robust/. If the OP
wants/needs to match numbers even with leading zeroes your /more robust/
version fails.
~Ethan~
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Re: Help with regex
On Thu, 06 Aug 2009 08:35:57 -0700, Robert Dailey wrote:
> I'm creating a python script that is going to try to search a text
> file for any text that matches my regular expression. The thing it is
> looking for is:
>
> FILEVERSION #,#,#,#
>
> The # symbol represents any number that can be any length 1 or
> greater. Example:
>
> FILEVERSION 1,45,10082,3
>
> The regex should only match the exact above. So far here's what I have
> come up with:
>
> re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
[0-9]+ allows any number of leading zeros, which is sometimes undesirable.
Using:
(0|[1-9][0-9]*)
is more robust.
--
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Re: Help with regex
On Aug 6, 11:12 am, Roman wrote:
> On 06/08/09 08:35, Robert Dailey wrote:
>
>
>
>
>
> > Hey guys,
>
> > I'm creating a python script that is going to try to search a text
> > file for any text that matches my regular expression. The thing it is
> > looking for is:
>
> > FILEVERSION #,#,#,#
>
> > The # symbol represents any number that can be any length 1 or
> > greater. Example:
>
> > FILEVERSION 1,45,10082,3
>
> > The regex should only match the exact above. So far here's what I have
> > come up with:
>
> > re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
>
> > This works, but I was hoping for something a bit cleaner. I'm having
> > to create a special case portion of the regex for the last of the 4
> > numbers simply because it doesn't end with a comma like the first 3.
> > Is there a better, more compact, way to write this regex?
> > --
> >http://mail.python.org/mailman/listinfo/python-list
>
> Since there cannot be more than one "end of string" you can try this
> expression:
> re.compile( r'FILEVERSION (?:[0-9]+(,|$)){4}' )
I had thought of this but I can't use that either. I have to assume
that someone was silly and put text at the end somewhere, perhaps a
comment. Like so:
FILEVERSION 1,2,3,4 // This is the file version
It would be nice if there was a type of counter for regex. So you
could say 'match only 1 [^,]' or something like that...
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Re: Help with regex
On 06/08/09 08:35, Robert Dailey wrote:
> Hey guys,
>
> I'm creating a python script that is going to try to search a text
> file for any text that matches my regular expression. The thing it is
> looking for is:
>
> FILEVERSION #,#,#,#
>
> The # symbol represents any number that can be any length 1 or
> greater. Example:
>
> FILEVERSION 1,45,10082,3
>
> The regex should only match the exact above. So far here's what I have
> come up with:
>
> re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
>
> This works, but I was hoping for something a bit cleaner. I'm having
> to create a special case portion of the regex for the last of the 4
> numbers simply because it doesn't end with a comma like the first 3.
> Is there a better, more compact, way to write this regex?
> --
> http://mail.python.org/mailman/listinfo/python-list
>
Since there cannot be more than one "end of string" you can try this
expression:
re.compile( r'FILEVERSION (?:[0-9]+(,|$)){4}' )
--
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Re: Help with regex
Robert Dailey wrote:
On Aug 6, 11:02 am, MRAB wrote:
Robert Dailey wrote:
Hey guys,
I'm creating a python script that is going to try to search a text
file for any text that matches my regular expression. The thing it is
looking for is:
FILEVERSION #,#,#,#
The # symbol represents any number that can be any length 1 or
greater. Example:
FILEVERSION 1,45,10082,3
The regex should only match the exact above. So far here's what I have
come up with:
re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
This works, but I was hoping for something a bit cleaner. I'm having
to create a special case portion of the regex for the last of the 4
numbers simply because it doesn't end with a comma like the first 3.
Is there a better, more compact, way to write this regex?
The character class \d is equivalent to [0-9], and ',' isn't a special
character so it doesn't need to be escaped:
re.compile(r'FILEVERSION (?:\d+,){3}\d+')
But ',' is a special symbol It's used in this way:
{0,3}
This will match the previous regex 0-3 times. Are you sure commas need
not be escaped?
In any case, your suggestions help to clean it up a bit!
By 'special' I mean ones like '?', '*', '(', etc. ',' isn't special in
that sense.
In fact, the {...} quantifier is special only if it's syntactically
correct, otherwise it's just a literal, eg "a{," and a{} are just
literals.
--
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Re: Help with regex
On Aug 6, 11:02 am, MRAB wrote:
> Robert Dailey wrote:
> > Hey guys,
>
> > I'm creating a python script that is going to try to search a text
> > file for any text that matches my regular expression. The thing it is
> > looking for is:
>
> > FILEVERSION #,#,#,#
>
> > The # symbol represents any number that can be any length 1 or
> > greater. Example:
>
> > FILEVERSION 1,45,10082,3
>
> > The regex should only match the exact above. So far here's what I have
> > come up with:
>
> > re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
>
> > This works, but I was hoping for something a bit cleaner. I'm having
> > to create a special case portion of the regex for the last of the 4
> > numbers simply because it doesn't end with a comma like the first 3.
> > Is there a better, more compact, way to write this regex?
>
> The character class \d is equivalent to [0-9], and ',' isn't a special
> character so it doesn't need to be escaped:
>
> re.compile(r'FILEVERSION (?:\d+,){3}\d+')
But ',' is a special symbol It's used in this way:
{0,3}
This will match the previous regex 0-3 times. Are you sure commas need
not be escaped?
In any case, your suggestions help to clean it up a bit!
--
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Re: Help with regex
On Aug 7, 1:35 am, Robert Dailey wrote:
> I'm creating a python script that is going to try to search a text
> file for any text that matches my regular expression. The thing it is
> looking for is:
>
> FILEVERSION 1,45,10082,3
Would it be easier to do it without regex? The following is untested
but I would probably do it more like this:
TOKEN = 'FILEVERSION '
for line in file:
if line.startswith(TOKEN):
version = line[len(TOKEN):]
maj, min, rev, other = version.split(',')
break # if there's only one occurance, otherwise do stuff here
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Re: Help with regex
Robert Dailey wrote:
Hey guys,
I'm creating a python script that is going to try to search a text
file for any text that matches my regular expression. The thing it is
looking for is:
FILEVERSION #,#,#,#
The # symbol represents any number that can be any length 1 or
greater. Example:
FILEVERSION 1,45,10082,3
The regex should only match the exact above. So far here's what I have
come up with:
re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
This works, but I was hoping for something a bit cleaner. I'm having
to create a special case portion of the regex for the last of the 4
numbers simply because it doesn't end with a comma like the first 3.
Is there a better, more compact, way to write this regex?
The character class \d is equivalent to [0-9], and ',' isn't a special
character so it doesn't need to be escaped:
re.compile(r'FILEVERSION (?:\d+,){3}\d+')
--
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Help with regex
Hey guys,
I'm creating a python script that is going to try to search a text
file for any text that matches my regular expression. The thing it is
looking for is:
FILEVERSION #,#,#,#
The # symbol represents any number that can be any length 1 or
greater. Example:
FILEVERSION 1,45,10082,3
The regex should only match the exact above. So far here's what I have
come up with:
re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
This works, but I was hoping for something a bit cleaner. I'm having
to create a special case portion of the regex for the last of the 4
numbers simply because it doesn't end with a comma like the first 3.
Is there a better, more compact, way to write this regex?
--
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Re: Help with Regex for domain names
In article , MRAB wrote: >Nobody wrote: >> On Thu, 30 Jul 2009 10:29:09 -0700, rurpy wrote: >> regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)') >>> You might also want to consider that some country >>> codes such as "co" for Columbia might match more than >>> you want, for example: >>> >>> re.match(r'[\w\-\.]+\.(?:us|au|de|co)', 'foo.boo.com') >>> >>> will match. >> >> ... so put \b at the end, i.e.: >> >> regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)\b') >> >It would still match "www.bbc.co.uk", so you might need: > >regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)\b(?!\.\b)') If it's a string containing just the candidate domain, you can do regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)$') -- Aahz (a...@pythoncraft.com) <*> http://www.pythoncraft.com/ "Many customs in this life persist because they ease friction and promote productivity as a result of universal agreement, and whether they are precisely the optimal choices is much less important." --Henry Spencer -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regex for domain names
Nobody wrote: On Thu, 30 Jul 2009 10:29:09 -0700, rurpy wrote: regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)') You might also want to consider that some country codes such as "co" for Columbia might match more than you want, for example: re.match(r'[\w\-\.]+\.(?:us|au|de|co)', 'foo.boo.com') will match. ... so put \b at the end, i.e.: regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)\b') It would still match "www.bbc.co.uk", so you might need: regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)\b(?!\.\b)') -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regex for domain names
On Thu, 30 Jul 2009 10:29:09 -0700, rurpy wrote: >> regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)') > > You might also want to consider that some country > codes such as "co" for Columbia might match more than > you want, for example: > > re.match(r'[\w\-\.]+\.(?:us|au|de|co)', 'foo.boo.com') > > will match. ... so put \b at the end, i.e.: regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)\b') -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regex for domain names
On Jul 30, 9:56 am, MRAB wrote: > Feyo wrote: > > I'm trying to figure out how to write efficiently write a regex for > > domain names with a particular top level domain. Let's say, I want to > > grab all domain names with country codes .us, .au, and .de. > > > I could create three different regexs that would work: > > regex = re.compile(r'[\w\-\.]+\.us) > > regex = re.compile(r'[\w\-\.]+\.au) > > regex = re.compile(r'[\w\-\.]+\.de) > > > How would I write one to accommodate all three, or, better yet, to > > accommodate a list of them that I can pass into a method call? Thanks! > > > > regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)') You might also want to consider that some country codes such as "co" for Columbia might match more than you want, for example: re.match(r'[\w\-\.]+\.(?:us|au|de|co)', 'foo.boo.com') will match. -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regex for domain names
On Jul 30, 11:56 am, MRAB wrote: > Feyo wrote: > > I'm trying to figure out how to write efficiently write a regex for > > domain names with a particular top level domain. Let's say, I want to > > grab all domain names with country codes .us, .au, and .de. > > > I could create three different regexs that would work: > > regex = re.compile(r'[\w\-\.]+\.us) > > regex = re.compile(r'[\w\-\.]+\.au) > > regex = re.compile(r'[\w\-\.]+\.de) > > > How would I write one to accommodate all three, or, better yet, to > > accommodate a list of them that I can pass into a method call? Thanks! > > > > regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)') > > If you have a list of country codes ["us", "au", "de"] then you can > build the regular expression from it: > > regex = re.compile(r'[\w\-\.]+\.(?:%s)' % '|'.join(domains)) Perfect! Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regex for domain names
Feyo wrote: I'm trying to figure out how to write efficiently write a regex for domain names with a particular top level domain. Let's say, I want to grab all domain names with country codes .us, .au, and .de. I could create three different regexs that would work: regex = re.compile(r'[\w\-\.]+\.us) regex = re.compile(r'[\w\-\.]+\.au) regex = re.compile(r'[\w\-\.]+\.de) How would I write one to accommodate all three, or, better yet, to accommodate a list of them that I can pass into a method call? Thanks! > regex = re.compile(r'[\w\-\.]+\.(?:us|au|de)') If you have a list of country codes ["us", "au", "de"] then you can build the regular expression from it: regex = re.compile(r'[\w\-\.]+\.(?:%s)' % '|'.join(domains)) -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regex for domain names
Feyo wrote: > I'm trying to figure out how to write efficiently write a regex for > domain names with a particular top level domain. Let's say, I want to > grab all domain names with country codes .us, .au, and .de. > > I could create three different regexs that would work: > regex = re.compile(r'[\w\-\.]+\.us) > regex = re.compile(r'[\w\-\.]+\.au) > regex = re.compile(r'[\w\-\.]+\.de) > > How would I write one to accommodate all three, or, better yet, to > accommodate a list of them that I can pass into a method call? Thanks! Just a point of interest: A correctly formed domain name may have a trailing period at the end of the TLD [1]. Example: foo.bar.com. Though you do not often see this, it's worth accommodating "just in case"... [1] http://homepages.tesco.net/J.deBoynePollard/FGA/web-fully-qualified-domain-name.html -- Tim Daneliuk tun...@tundraware.com PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
Help with Regex for domain names
I'm trying to figure out how to write efficiently write a regex for domain names with a particular top level domain. Let's say, I want to grab all domain names with country codes .us, .au, and .de. I could create three different regexs that would work: regex = re.compile(r'[\w\-\.]+\.us) regex = re.compile(r'[\w\-\.]+\.au) regex = re.compile(r'[\w\-\.]+\.de) How would I write one to accommodate all three, or, better yet, to accommodate a list of them that I can pass into a method call? Thanks! -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie needs help with regex strings
Catalina Scott A Contr AFCA/EVEO wrote:
> I have a file with lines in the following format.
>
> pie=apple,quantity=1,cooked=yes,ingredients='sugar and cinnamon'
> Pie=peach,quantity=2,ingredients='peaches,powdered sugar'
> Pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and sugar'
>
> I would like to pull out some of the values and write them to a csv
> file.
>
> For line in filea
> pie = regex
> quantity = regex
> cooked = regex
> ingredients = regex
> fileb.write (quantity,pie,cooked,ingredients)
>
> How can I retreive the values and assign them to a name?
>
> Thank you
> Scott
Here's a trick to parse this source, exploiting the fact that its syntax mimics
python's keyword arguments. All that's needed is a way to quote the bare names:
>>> class lazynames(dict):
... def __getitem__(self, key):
... if key in self:
... return dict.__getitem__(self, key)
... return "%s" % key # if name not found, return it as a str constant
...
>>> d = lazynames(dict=dict, __builtins__ = None)
>>> source = """\
... pie=apple,quantity=1,cooked=yes,ingredients='sugar and cinnamon'
... Pie=peach,quantity=2,ingredients='peaches,powdered sugar'
... Pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and sugar'
... """
>>>
>>> [eval("dict(%s)" % line, d) for line in source.splitlines()]
[{'cooked': 'yes', 'ingredients': 'sugar and cinnamon', 'pie': 'apple',
'quantity': 1}, {'ingredients': 'peaches,powdered sugar', 'Pie': 'peach',
'quantity': 2}, {'cooked': 'no', 'price': 5, 'ingredients': 'cherries and
sugar', 'Pie': 'cherry', 'quantity': 3}]
>>>
Michael
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Re: Newbie needs help with regex strings
Dennis Benzinger wrote: > Christopher Subich schrieb: >> Paul McGuire wrote: >> >> [...] >> For the example listed, pyparsing is even overkill; the OP should >> probably use the csv module. > > But the OP wants to parse lines with key=value pairs, not simply lines > with comma separated values. Using the csv module will just separate the > key=value pairs and you would still have to take them apart. > > Bye, > Dennis that, and csv.reader has another problem with this task: >>> csv.reader(["Pie=peach,quantity=2,ingredients='peaches,powdered sugar'"], quotechar = "'").next() ['Pie=peach', 'quantity=2', "ingredients='peaches", "powdered sugar'"] i.e., it doesn't allow separators within fields unless either the *whole* field is quoted: >>> csv.reader(["Pie=peach,quantity=2,'ingredients=peaches,powdered sugar'"], quotechar = "'").next() ['Pie=peach', 'quantity=2', 'ingredients=peaches,powdered sugar'] >>> or the separator is escaped: >>> csv.reader(["Pie=peach,quantity=2,ingredients='peaches\,powdered sugar'"], quotechar = "'", escapechar = "\\").next() ['Pie=peach', 'quantity=2', "ingredients='peaches,powdered sugar'"] >>> Michael -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie needs help with regex strings
Fredrik Lundh wrote:
> Scott wrote:
>
> > I have a file with lines in the following format.
> >
> > pie=apple,quantity=1,cooked=yes,ingredients='sugar and cinnamon'
> > Pie=peach,quantity=2,ingredients='peaches,powdered sugar'
> > Pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and sugar'
> >
> > I would like to pull out some of the values and write them to a csv
> > file.
>
> here's a relatively straightforward re solution that gives you a dictionary
> with the values for each line.
>
> import re
>
> for line in open("infile.txt"):
> d = {}
> for k, v1, v2 in re.findall("(\w+)=(?:(\w+)|'([^']*)')", line):
> d[k.lower()] = v1 or v2
> print d
>
How about replacing
d={}
with
d = {'pie': ',', 'quantity': ',', 'cooked': ',', 'price':
',','ingredients': '', 'eol': '\n'}
to get the appropriate commas for missing fields?
Gerard
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Re: Newbie needs help with regex strings
Christopher Subich schrieb: > Paul McGuire wrote: > > [...] > For the example listed, pyparsing is even overkill; the OP should > probably use the csv module. But the OP wants to parse lines with key=value pairs, not simply lines with comma separated values. Using the csv module will just separate the key=value pairs and you would still have to take them apart. Bye, Dennis -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie needs help with regex strings
Catalina Scott A Contr AFCA/EVEO schrieb:
> I have a file with lines in the following format.
>
> pie=apple,quantity=1,cooked=yes,ingredients='sugar and cinnamon'
> Pie=peach,quantity=2,ingredients='peaches,powdered sugar'
> Pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and sugar'
>
> I would like to pull out some of the values and write them to a csv
> file.
>
> For line in filea
> pie = regex
> quantity = regex
> cooked = regex
> ingredients = regex
> fileb.write (quantity,pie,cooked,ingredients)
>
> How can I retreive the values and assign them to a name?
>
> Thank you
> Scott
Try this:
import re
import StringIO
filea_string = """pie=apple,quantity=1,cooked=yes,ingredients='sugar and
cinnamon'
pie=peach,quantity=2,ingredients='peaches,powdered sugar'
pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and sugar'
"""
FIELDS = ("pie", "quantity", "cooked", "ingredients", "price")
field_regexes = {}
for field in FIELDS:
field_regexes[field] = re.compile("%s=([^,\n]*)" % field)
for line in StringIO.StringIO(filea_string):
field_values = {}
for field in FIELDS:
match_object = field_regexes[field].search(line)
if match_object is not None:
field_values[field] = match_object.group(1)
print field_values
#fileb.write (quantity,pie,cooked,ingredients)
Bye,
Dennis
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Re: Newbie needs help with regex strings
Paul McGuire wrote: > This isn't a regex solution, but uses pyparsing instead. Pyparsing > helps you construct recursive-descent parsers, and maintains a code > structure that is easy to compose, read, understand, maintain, and > remember what you did 6-months after you wrote it in the first place. > > Download pyparsing at http://pyparsing.sourceforge.net. For the example listed, pyparsing is even overkill; the OP should probably use the csv module. -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie needs help with regex strings
Scott wrote:
> I have a file with lines in the following format.
>
> pie=apple,quantity=1,cooked=yes,ingredients='sugar and cinnamon'
> Pie=peach,quantity=2,ingredients='peaches,powdered sugar'
> Pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and sugar'
>
> I would like to pull out some of the values and write them to a csv
> file.
>
> For line in filea
> pie = regex
> quantity = regex
> cooked = regex
> ingredients = regex
> fileb.write (quantity,pie,cooked,ingredients)
>
> How can I retreive the values and assign them to a name?
here's a relatively straightforward re solution that gives you a dictionary
with the values for each line.
import re
for line in open("infile.txt"):
d = {}
for k, v1, v2 in re.findall("(\w+)=(?:(\w+)|'([^']*)')", line):
d[k.lower()] = v1 or v2
print d
(the pattern looks for alphanumeric characters (k) followed by an equal
sign followed by either a number of alphanumeric characters (v1), or text
inside single quotes (v2). either v1 or v2 will be set)
getting from dictionary to file is left as an exercise to the reader.
--
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Re: Newbie needs help with regex strings
This isn't a regex solution, but uses pyparsing instead. Pyparsing
helps you construct recursive-descent parsers, and maintains a code
structure that is easy to compose, read, understand, maintain, and
remember what you did 6-months after you wrote it in the first place.
Download pyparsing at http://pyparsing.sourceforge.net.
-- Paul
data = """pie=apple,quantity=1,cooked=yes,ingredients='sugar and
cinnamon'
Pie=peach,quantity=2,ingredients='peaches,powdered sugar'
Pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and
sugar'"""
from pyparsing import CaselessLiteral, Literal, Word, alphas, nums,
oneOf, quotedString, \
Group, Dict, delimitedList, removeQuotes
# define basic elements for parsing
pieName = Word(alphas)
qty = Word(nums)
yesNo = oneOf("yes no",caseless=True)
EQUALS = Literal("=").suppress()
# define separate pie attributes
pieEntry = CaselessLiteral("pie") + EQUALS + pieName
qtyEntry = CaselessLiteral("quantity") + EQUALS + qty
cookedEntry = CaselessLiteral("cooked") + EQUALS + yesNo
ingredientsEntry = CaselessLiteral("ingredients") + EQUALS +
quotedString.setParseAction(removeQuotes)
priceEntry = CaselessLiteral("price") + EQUALS + qty
# define overall list of alternative attributes
pieAttribute = pieEntry | qtyEntry | cookedEntry | ingredientsEntry |
priceEntry
# define each line as a list of attributes (comma delimiter is the
default), grouping results by attribute
pieDataFormat = delimitedList( Group(pieAttribute) )
# parse each line in the input string, and create a dict of the results
for line in data.split("\n"):
pieData = pieDataFormat.parseString(line)
pieDict = dict( pieData.asList() )
print pieDict
''' prints out:
{'cooked': 'yes', 'ingredients': 'sugar and cinnamon', 'pie': 'apple',
'quantity': '1'}
{'ingredients': 'peaches,powdered sugar', 'pie': 'peach', 'quantity':
'2'}
{'cooked': 'no', 'price': '5', 'ingredients': 'cherries and sugar',
'pie': 'cherry', 'quantity': '3'}
'''
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Newbie needs help with regex strings
I have a file with lines in the following format. pie=apple,quantity=1,cooked=yes,ingredients='sugar and cinnamon' Pie=peach,quantity=2,ingredients='peaches,powdered sugar' Pie=cherry,quantity=3,cooked=no,price=5,ingredients='cherries and sugar' I would like to pull out some of the values and write them to a csv file. For line in filea pie = regex quantity = regex cooked = regex ingredients = regex fileb.write (quantity,pie,cooked,ingredients) How can I retreive the values and assign them to a name? Thank you Scott -- http://mail.python.org/mailman/listinfo/python-list
