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Reverse string-formatting (maybe?)

Is there any builtin function or module with a function similar to my
made-up, not-written deformat function as follows? I can't imagine it
would be too easy to write, but possible...
>>template = 'I am %s, and he %s last %s.'
values = ('coding', "coded', 'week')
formatted = template % values
formatted
'I am coding, and he coded last week.'
>>deformat(form atted, template)
('coding', 'coded', 'week')

expanded (for better visual):
>>deformat('I am coding, and he coded last week.', 'I am %s, and he %s last %s.')
('coding', 'coded', 'week')

It would return a tuple of strings, since it has no way of telling what
the original type of each item was.
Any input? I've looked through the documentation of the string module
and re module, did a search of the documentation and a search of this
group, and come up empty-handed.

Oct 14 '06 #1
11 4989
Dustan wrote:
Is there any builtin function or module with a function similar to my
made-up, not-written deformat function as follows? I can't imagine it
would be too easy to write, but possible...
>>>template = 'I am %s, and he %s last %s.'
values = ('coding', "coded', 'week')
formatted = template % values
formatted
'I am coding, and he coded last week.'
>>>deformat(for matted, template)
('coding', 'coded', 'week')

expanded (for better visual):
>>>deformat(' I am coding, and he coded last week.', 'I am %s, and he %s
last %s.')
('coding', 'coded', 'week')

It would return a tuple of strings, since it has no way of telling what
the original type of each item was.
Any input? I've looked through the documentation of the string module
and re module, did a search of the documentation and a search of this
group, and come up empty-handed.
Simple, but unreliable:
>>import re
template = "I am %s, and he %s last %s."
values = ("coding", "coded", "week")
formatted = template % values
def deformat(format ted, template):
.... r = re.compile("(.* )".join(templat e.split("%s")))
.... return r.match(formatt ed).groups()
....
>>deformat(form atted, template)
('coding', 'coded', 'week')

Peter
Oct 14 '06 #2
>>>template = 'I am %s, and he %s last %s.'
>>>values = ('coding', "coded', 'week')
formatted = template % values
formatted
'I am coding, and he coded last week.'
>>>deformat(for matted, template)
('coding', 'coded', 'week')

expanded (for better visual):
>>>deformat(' I am coding, and he coded last week.', 'I am %s, and he %s last %s.')
('coding', 'coded', 'week')

It would return a tuple of strings, since it has no way of telling what
the original type of each item was.

Any input? I've looked through the documentation of the string module
and re module, did a search of the documentation and a search of this
group, and come up empty-handed.

Yes, in the trivial case you provide, it can be done fairly
easily using the re module:
>>import re
template = 'I am %s, and he %s last %s.'
values = ('coding', 'coded', 'week')
formatted = template % values
unformat_re = re.escape(templ ate).replace('% s', '(.*)')
# unformat_re = unformat_re.rep lace('%i', '([0-9]+)')
r = re.compile(unfo rmat_re)
r.match(forma tted).groups()
('coding', 'coded', 'week')

Thing's get crazier when you have things like
>>answer ='format values into a string'
template = 'The formatting string %%s is used to %s' % answer
or
>>template = 'The value is %0*.*f'
values = (10, 4, 3.14159)
formatted = template % values
formated
'The value is 00003.1415'

or
>>template = 'Dear %(name)s, Thank you for the %(gift)s. It
was very %(adj).' % {'name': 'Grandma', 'gift': 'sweater', 'adj':
'nice'}

Additionally, things go a little tangled when the replacement
values duplicate matters in the template. Should the unformatting
of "I am tired, and he didn't last last All Saint's Day" be
parsed as ('tired', "didn't last", "All Saint's Day") or
('tired', "didn't", "last All Saint's Day"). The /intent/ is
likely the former, but getting a computer to understand intent is
a non-trivial task ;)

Just a few early-morning thoughts...

-tkc


Oct 14 '06 #3
>>>template = 'I am %s, and he %s last %s.'
>>>values = ('coding', "coded', 'week')
formatted = template % values
formatted
'I am coding, and he coded last week.'
>>>deformat(for matted, template)
('coding', 'coded', 'week')

expanded (for better visual):
>>>deformat(' I am coding, and he coded last week.', 'I am %s, and he %s last %s.')
('coding', 'coded', 'week')

It would return a tuple of strings, since it has no way of telling what
the original type of each item was.

Any input? I've looked through the documentation of the string module
and re module, did a search of the documentation and a search of this
group, and come up empty-handed.

Yes, in the trivial case you provide, it can be done fairly
easily using the re module:
>>import re
template = 'I am %s, and he %s last %s.'
values = ('coding', 'coded', 'week')
formatted = template % values
unformat_re = re.escape(templ ate).replace('% s', '(.*)')
# unformat_re = unformat_re.rep lace('%i', '([0-9]+)')
r = re.compile(unfo rmat_re)
r.match(forma tted).groups()
('coding', 'coded', 'week')

Thing's get crazier when you have things like
>>answer ='format values into a string'
template = 'The formatting string %%s is used to %s' % answer
or
>>template = 'The value is %0*.*f'
values = (10, 4, 3.14159)
formatted = template % values
formated
'The value is 00003.1415'

or
>>template = 'Dear %(name)s, Thank you for the %(gift)s. It
was very %(adj).' % {'name': 'Grandma', 'gift': 'sweater', 'adj':
'nice'}

Additionally, things go a little tangled when the replacement
values duplicate matters in the template. Should the unformatting
of "I am tired, and he didn't last last All Saint's Day" be
parsed as ('tired', "didn't last", "All Saint's Day") or
('tired', "didn't", "last All Saint's Day"). The /intent/ is
likely the former, but getting a computer to understand intent is
a non-trivial task ;)

Just a few early-morning thoughts...

-tkc


Oct 14 '06 #4

Peter Otten wrote:
Dustan wrote:
Is there any builtin function or module with a function similar to my
made-up, not-written deformat function as follows? I can't imagine it
would be too easy to write, but possible...
>>template = 'I am %s, and he %s last %s.'
values = ('coding', "coded', 'week')
formatted = template % values
formatted
'I am coding, and he coded last week.'
>>deformat(form atted, template)
('coding', 'coded', 'week')

expanded (for better visual):
>>deformat('I am coding, and he coded last week.', 'I am %s, and he %s
last %s.')
('coding', 'coded', 'week')

It would return a tuple of strings, since it has no way of telling what
the original type of each item was.
Any input? I've looked through the documentation of the string module
and re module, did a search of the documentation and a search of this
group, and come up empty-handed.

Simple, but unreliable:
>import re
template = "I am %s, and he %s last %s."
values = ("coding", "coded", "week")
formatted = template % values
def deformat(format ted, template):
... r = re.compile("(.* )".join(templat e.split("%s")))
... return r.match(formatt ed).groups()
...
>deformat(forma tted, template)
('coding', 'coded', 'week')

Peter
Trying to figure out the 'unreliable' part of your statement...

I'm sure 2 '%s' characters in a row would be a bad idea, and if you
have similar expressions for the '%s' characters within as well as in
the neighborhood of the '%s', that would cause difficulty. Is there any
other reason it might not work properly?

My template outside of the '%s' characters contains only commas and
spaces, and within, neither commas nor spaces. Given that information,
is there any reason it might not work properly?

Oct 15 '06 #5
My template outside of the '%s' characters contains only commas and
spaces, and within, neither commas nor spaces. Given that information,
is there any reason it might not work properly?
Given this new (key) information along with the assumption that
you're doing straight string replacement (not dictionary
replacement of the form "%(key)s" or other non-string types such
as "%05.2f"), then yes, a reversal is possible. To make it more
explicit, one would do something like
>>template = '%s, %s, %s'
values = ('Tom', 'Dick', 'Harry')
formatted = template % values
import re
unformat_stri ng = template.replac e('%s', '([^, ]+)')
unformatter = re.compile(unfo rmat_string)
extracted_val ues = unformatter.sea rch(formatted). groups()
using '[^, ]+' to mean "one or more characters that aren't a
comma or a space".

-tkc


Oct 15 '06 #6

Tim Chase wrote:
My template outside of the '%s' characters contains only commas and
spaces, and within, neither commas nor spaces. Given that information,
is there any reason it might not work properly?

Given this new (key) information along with the assumption that
you're doing straight string replacement (not dictionary
replacement of the form "%(key)s" or other non-string types such
as "%05.2f"), then yes, a reversal is possible. To make it more
explicit, one would do something like
>>template = '%s, %s, %s'
>>values = ('Tom', 'Dick', 'Harry')
>>formatted = template % values
>>import re
>>unformat_stri ng = template.replac e('%s', '([^, ]+)')
>>unformatter = re.compile(unfo rmat_string)
>>extracted_val ues = unformatter.sea rch(formatted). groups()

using '[^, ]+' to mean "one or more characters that aren't a
comma or a space".

-tkc
Thanks.

One more thing (I forgot to mention this other situation earlier)
The %s characters are ints, and outside can be anything except int
characters. I do have one situation of '%s%s%s', but I can change it to
'%s', and change the output into the needed output, so that's not
important. Think something along the lines of "abckdaldj iweo%s
qwierxcnv !%sjd".

Oct 15 '06 #7

Dustan wrote:
Tim Chase wrote:
My template outside of the '%s' characters contains only commas and
spaces, and within, neither commas nor spaces. Given that information,
is there any reason it might not work properly?
Given this new (key) information along with the assumption that
you're doing straight string replacement (not dictionary
replacement of the form "%(key)s" or other non-string types such
as "%05.2f"), then yes, a reversal is possible. To make it more
explicit, one would do something like
>>template = '%s, %s, %s'
>>values = ('Tom', 'Dick', 'Harry')
>>formatted = template % values
>>import re
>>unformat_stri ng = template.replac e('%s', '([^, ]+)')
>>unformatter = re.compile(unfo rmat_string)
>>extracted_val ues = unformatter.sea rch(formatted). groups()
using '[^, ]+' to mean "one or more characters that aren't a
comma or a space".

-tkc

Thanks.

One more thing (I forgot to mention this other situation earlier)
The %s characters are ints, and outside can be anything except int
characters. I do have one situation of '%s%s%s', but I can change it to
'%s', and change the output into the needed output, so that's not
important. Think something along the lines of "abckdaldj iweo%s
qwierxcnv !%sjd".
That was written in haste. All the information is true. The question:
I've already created a function to do this, using your original
deformat function. Is there any way in which it might go wrong?

Oct 15 '06 #8

Dustan wrote:
Dustan wrote:
Tim Chase wrote:
My template outside of the '%s' characters contains only commas and
spaces, and within, neither commas nor spaces. Given that information,
is there any reason it might not work properly?
>
Given this new (key) information along with the assumption that
you're doing straight string replacement (not dictionary
replacement of the form "%(key)s" or other non-string types such
as "%05.2f"), then yes, a reversal is possible. To make it more
explicit, one would do something like
>
>>template = '%s, %s, %s'
>>values = ('Tom', 'Dick', 'Harry')
>>formatted = template % values
>>import re
>>unformat_stri ng = template.replac e('%s', '([^, ]+)')
>>unformatter = re.compile(unfo rmat_string)
>>extracted_val ues = unformatter.sea rch(formatted). groups()
>
using '[^, ]+' to mean "one or more characters that aren't a
comma or a space".
>
-tkc
Thanks.

One more thing (I forgot to mention this other situation earlier)
The %s characters are ints, and outside can be anything except int
characters. I do have one situation of '%s%s%s', but I can change it to
'%s', and change the output into the needed output, so that's not
important. Think something along the lines of "abckdaldj iweo%s
qwierxcnv !%sjd".

That was written in haste. All the information is true. The question:
I've already created a function to do this, using your original
deformat function. Is there any way in which it might go wrong?
Again, haste. I used Peter's deformat function.

Oct 15 '06 #9
On 14 Oct 2006 05:35:02 -0700,
"Dustan" <Du**********@g mail.comwrote:
Is there any builtin function or module with a function similar to my
made-up, not-written deformat function as follows? I can't imagine it
would be too easy to write, but possible...
[ snip ]
Any input? I've looked through the documentation of the string module
and re module, did a search of the documentation and a search of this
group, and come up empty-handed.
Track down pyscanf. (Google is your friend, but I can't find any sort
of licensing/copyright information, and the web addresses in the source
code aren't available, so I hesitate to post my ancient copy.)

HTH,
Dan

--
Dan Sommers
<http://www.tombstoneze ro.net/dan/>
"I wish people would die in alphabetical order." -- My wife, the genealogist
Oct 15 '06 #10

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