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ascii character - removing chars from string

 
 
bruce
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      07-03-2006
hi...

i'm running into a problem where i'm seeing non-ascii chars in the parsing
i'm doing. in looking through various docs, i can't find functions to
remove/restrict strings to valid ascii chars.

i'm assuming python has something like

valid_str = strip(invalid_str)

where 'strip' removes/strips out the invalid chars...

any ideas/thoughts/pointers...

thanks

-bruce

 
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bearophileHUGS@lycos.com
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      07-03-2006
bruce:
> valid_str = strip(invalid_str)
> where 'strip' removes/strips out the invalid chars...


This isn't short but it is fast:
import string
valid_chars = string.lowercase + string.uppercase + \
string.digits +
"""|!'\\"$%&/()=?^*_:;>+,.-<\n \t"""
all_chars = "".join(map( chr, range(256)) )
comp_valid_chars = "".join( set(all_chars).difference(valid_chars) )
print "test string".translate(all_chars, comp_valid_chars)


Shorter and a bit slower alternative:
import string
valid_chars_set = set(string.lowercase + string.uppercase
+ string.digits +
"""|!'\\"$%&/()=?^*_:;>+,.-<\n \t""")
print filter(lambda c: c in valid_chars_set, "test string")

You can add the chars you want to the string of accepted ones.

Bye,
bearophile

 
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John Machin
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      07-04-2006
On 4/07/2006 9:27 AM, bruce wrote:
> hi...
>
> i'm running into a problem where i'm seeing non-ascii chars in the parsing
> i'm doing. in looking through various docs, i can't find functions to
> remove/restrict strings to valid ascii chars.
>


It's possible that you would be better off handling those characters in
some fashion other than blowing them away. What are the characters that
you are seeing, and what is the problem that they are causing you?
 
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Rune Strand
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Posts: n/a
 
      07-04-2006
bruce wrote:
> hi...
>
> i'm running into a problem where i'm seeing non-ascii chars in the parsing
> i'm doing. in looking through various docs, i can't find functions to
> remove/restrict strings to valid ascii chars.
>
> i'm assuming python has something like
>
> valid_str = strip(invalid_str)
>
> where 'strip' removes/strips out the invalid chars...
>
> any ideas/thoughts/pointers...


If you're able to define the invalid_chars, the most convenient is
probably to use the strip() method:
>>> a_string = "abcdef"
>>> invalid_chars = 'abc'
>>> a_string.strip(invalid_chars)

'def'

 
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Simon Forman
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      07-04-2006
bruce wrote:
> hi...
>
> i'm running into a problem where i'm seeing non-ascii chars in the parsing
> i'm doing. in looking through various docs, i can't find functions to
> remove/restrict strings to valid ascii chars.
>
> i'm assuming python has something like
>
> valid_str = strip(invalid_str)
>
> where 'strip' removes/strips out the invalid chars...
>
> any ideas/thoughts/pointers...
>
> thanks
>
> -bruce


You might be able to use the translate() and maketrans() string
methods. See
http://groups.google.ca/group/comp.l...02a21c95bd0ec9
second-to-last post for an example.

 
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Simon Forman
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      07-04-2006
bruce wrote:
> hi...
>
> update. i'm getting back html, and i'm getting strings like " foo &nbsp;"
> which is valid HTML as the '&nbsp;' is a space.


&, n, b, s, p, ; Those are all ascii characters.

> i need a way of stripping/removing the '&nbsp;' from the string
>
> the &nbsp; needs to be treated as a single char...
>
> text = "foo cat &nbsp;"
>
> ie ok_text = strip(text)
>
> ok_text = "foo cat"


Do you really want to remove those html entities? Or would you rather
convert them back into the actual text they represent? Do you just
want to deal with &nbsp;'s? Or maybe the other possible entities that
might appear also?

Check out htmlentitydefs.entitydefs (see
http://docs.python.org/lib/module-htmlentitydefs.html) it's kind of
ugly looking so maybe use pprint to print it:

>>> import htmlentitydefs, pprint
>>> pprint.pprint(htmlentitydefs.entitydefs)

{'AElig': '',
'Aacute': '',
'Acirc': '',
..
..
..
'nbsp': '\xa0',
..
..
..
etc...


HTH,
~Simon

"You keep using that word. I do not think it means what you think it
means."
-Inigo Montoya, "The Princess Bride"

 
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Simon Forman
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Posts: n/a
 
      07-04-2006
bruce wrote:
> simon...
>
> the '&nbsp;' is not to be seen/viewed as text/ascii.. it's a representation
> of a hex 'u\xa0' if i recall...


Did you not see this part of the post that you're replying to?

> 'nbsp': '\xa0',


My point was not that '\xa0' is an ascii character... It was that your
initial request was very misleading:

"i'm running into a problem where i'm seeing non-ascii chars in the
parsing i'm doing. in looking through various docs, i can't find
functions to remove/restrict strings to valid ascii chars."

That's why you got three different answers to the wrong question.

You weren't "seeing non-ascii chars" at all. You were seeing ascii
representations of html entities that, in the case of '&nbsp;', happen
to represent non-ascii values.

>
> i'm looking to remove or replace the insances with a ' ' (space)


Simplicity:

s.replace('&nbsp;', ' ')

~Simon

"You keep using that word. I do not think it means what you think it
means."
-Inigo Montoya, "The Princess Bride"

>
> -bruce
>
>
> -----Original Message-----
> From: python-list-bounces+bedouglas=(E-Mail Removed)
> [mailtoython-list-bounces+bedouglas=(E-Mail Removed)]On Behalf
> Of Simon Forman
> Sent: Monday, July 03, 2006 7:17 PM
> To: http://www.velocityreviews.com/forums/(E-Mail Removed)
> Subject: Re: ascii character - removing chars from string
>
>
> bruce wrote:
> > hi...
> >
> > update. i'm getting back html, and i'm getting strings like " foo &nbsp;"
> > which is valid HTML as the '&nbsp;' is a space.

>
> &, n, b, s, p, ; Those are all ascii characters.
>
> > i need a way of stripping/removing the '&nbsp;' from the string
> >
> > the &nbsp; needs to be treated as a single char...
> >
> > text = "foo cat &nbsp;"
> >
> > ie ok_text = strip(text)
> >
> > ok_text = "foo cat"

>
> Do you really want to remove those html entities? Or would you rather
> convert them back into the actual text they represent? Do you just
> want to deal with &nbsp;'s? Or maybe the other possible entities that
> might appear also?
>
> Check out htmlentitydefs.entitydefs (see
> http://docs.python.org/lib/module-htmlentitydefs.html) it's kind of
> ugly looking so maybe use pprint to print it:
>
> >>> import htmlentitydefs, pprint
> >>> pprint.pprint(htmlentitydefs.entitydefs)

> {'AElig': '',
> 'Aacute': '',
> 'Acirc': '',
> .
> .
> .
> 'nbsp': '\xa0',
> .
> .
> .
> etc...
>
>
> HTH,
> ~Simon
>
> "You keep using that word. I do not think it means what you think it
> means."
> -Inigo Montoya, "The Princess Bride"
>
> --
> http://mail.python.org/mailman/listinfo/python-list


 
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