Deleting specific characters from a string

[Behrang Dadsetan]

Hi all,

I would like deleting specific characters from a string.
As an example, I would like to delete all of the '@' '&' in the string
'You are ben@orange?ente r&your&code' so that it becomes
'benorange?ente ryourcode'.

So far I have been doing it like:
str = 'You are ben@orange?ente r&your&code'
str = ''.join([ c for c in str if c not in ('@', '&')])

but that looks so ugly.. I am hoping to see nicer examples to acheive
the above..

Thanks.
Ben.

[Matt Shomphe]

Maybe a new method should be added to the str class, called "remove".
It would take a list of characters and remove them from the string:
class RemoveString(st r):
def __init__(self, s=None):
str.__init__(se lf, s)
def remove(self, chars):
s = self
for c in chars:
s = s.replace(c, '')
return(s)

if __name__ == '__main__':
r = RemoveString('a bc')
e = r.remove('c')
print r, e
# prints "abc ab" -- it's not "in place" removal

M@

Behrang Dadsetan <be*@dadsetan.c om> wrote in message news:<be******* ***@online.de>. ..

Hi all,

I would like deleting specific characters from a string.
As an example, I would like to delete all of the '@' '&' in the string
'You are ben@orange?ente r&your&code' so that it becomes
'benorange?ente ryourcode'.

So far I have been doing it like:
str = 'You are ben@orange?ente r&your&code'
str = ''.join([ c for c in str if c not in ('@', '&')])

but that looks so ugly.. I am hoping to see nicer examples to acheive
the above..

Thanks.
Ben.

[Donn Cave]

In article <5a************ **************@ posting.google. com>,
Ma******@HeyAni ta.com (Matt Shomphe) wrote:

Maybe a new method should be added to the str class, called "remove".
It would take a list of characters and remove them from the string:

Check out the translate function - that's what its optional
deletions argument is for.

Donn Cave, do**@u.washingt on.edu

[John Hunter]

>>>>> "Matt" == Matt Shomphe <Ma******@HeyAn ita.com> writes:

Matt> Maybe a new method should be added to the str class, called
Matt> "remove". It would take a list of characters and remove
Matt> them from the string:

you can use string translate for this, which is shorter and faster
than using the loop.

class rstr(str):
_allchars = "".join([chr(x) for x in range(256)])
def remove(self, chars):
return self.translate( self._allchars, chars)

me = rstr('John Hunter')
print me.remove('ohn' )

Also, you don't need to define a separate __init__, since you are nor
overloading the str default.

JDH

[Behrang Dadsetan]

Donn Cave wrote:

In article <5a************ **************@ posting.google. com>,
Ma******@HeyAni ta.com (Matt Shomphe) wrote:

Maybe a new method should be added to the str class, called "remove".
It would take a list of characters and remove them from the string:

Check out the translate function - that's what its optional
deletions argument is for.

str = 'You are Ben@orange?ente r&your&code'
str.translate(s tring.maketrans ('',''), '@&') and str.replace('&' , '').replace('@' , '')

are also ugly...

The first version is completely unreadable. I guess my initial example
''.join([ c for c in str if c not in ('@', '&')]) was easier to read
than the translate (who would guess -without having to peek in the
documentation of translate- that that line deletes @ and &?!) but I am
not sure ;)

while the second becomes acceptable. The examples you gave me use the
string module.
I think I read somewhere that the methods of the object should rather be
used than the string module. Is that right?

Thanks anyhow, I will go for the replace(somethi ng, '') method.
Ben.

[Walter Dörwald]

Behrang Dadsetan wrote:

Hi all,

I would like deleting specific characters from a string.
As an example, I would like to delete all of the '@' '&' in the string
'You are ben@orange?ente r&your&code' so that it becomes
'benorange?ente ryourcode'.

So far I have been doing it like:
str = 'You are ben@orange?ente r&your&code'
str = ''.join([ c for c in str if c not in ('@', '&')])

but that looks so ugly.. I am hoping to see nicer examples to acheive
the above..

What about the following:

str = 'You are ben@orange?ente r&your&code'
str = filter(lambda c: c not in "@&", str)

Bye,
Walter Dörwald

[Behrang Dadsetan]

Walter Dörwald wrote:

Behrang Dadsetan wrote:

Hi all,

I would like deleting specific characters from a string.
As an example, I would like to delete all of the '@' '&' in the
string 'You are ben@orange?ente r&your&code' so that it becomes
'benorange?ente ryourcode'.

So far I have been doing it like:
str = 'You are ben@orange?ente r&your&code'
str = ''.join([ c for c in str if c not in ('@', '&')])

but that looks so ugly.. I am hoping to see nicer examples to acheive
the above..

What about the following:

str = 'You are ben@orange?ente r&your&code'
str = filter(lambda c: c not in "@&", str)

Bye,
Walter Dörwald

def isAcceptableCha r(character):
return charachter in "@&"

str = filter(isAccept ableChar, str)

is going to finally be what I am going to use.
I not feel lambdas are so readable, unless one has serious experience in
using them and python in general. I feel it is acceptable to add a named
method that documents with its name what it is doing there.

But your example would probably have been my choice if I was more
familiar with that type of use and the potential readers of my code were
also familiar with it. Many thanks!

Ben.

[Walter Dörwald]

Behrang Dadsetan wrote:

Walter Dörwald wrote:

Behrang Dadsetan wrote:

Hi all,

I would like deleting specific characters from a string.
As an example, I would like to delete all of the '@' '&' in the
string 'You are ben@orange?ente r&your&code' so that it becomes
'benorange?ente ryourcode'.

So far I have been doing it like:
str = 'You are ben@orange?ente r&your&code'
str = ''.join([ c for c in str if c not in ('@', '&')])

but that looks so ugly.. I am hoping to see nicer examples to acheive
the above..
What about the following:

str = 'You are ben@orange?ente r&your&code'
str = filter(lambda c: c not in "@&", str)

Bye,
Walter Dörwald

def isAcceptableCha r(character):
return charachter in "@&"

str = filter(isAccept ableChar, str)

is going to finally be what I am going to use.
I not feel lambdas are so readable, unless one has serious experience in
using them and python in general. I feel it is acceptable to add a named
method that documents with its name what it is doing there.

You're not the only one with this feeling. Compare "the eff-bot's
favourite lambda refactoring rule":

http://groups.google.de/groups?selm=...ewsb.telia.net
[...]

Bye,
Walter Dörwald

[John Hunter]

>>>>> "Behrang" == Behrang Dadsetan <be*@dadsetan.c om> writes:

Behrang> is going to finally be what I am going to use. I not
Behrang> feel lambdas are so readable, unless one has serious
Behrang> experience in using them and python in general. I feel it
Behrang> is acceptable to add a named method that documents with
Behrang> its name what it is doing there.

If you want to go the functional programing route, you can generalize
your function somewhat using a callable class:

class remove_char:
def __init__(self,r emove):
self.remove = dict([ (c,1) for c in remove])

def __call__(self,c ):
return not self.remove.has _key(c)

print filter(remove_c har('on'), 'John Hunter')

Cheers,
Jh Huter

[Bengt Richter]

On Wed, 09 Jul 2003 23:36:03 +0200, Behrang Dadsetan <be*@dadsetan.c om> wrote:

Walter Dörwald wrote:

Behrang Dadsetan wrote:

Hi all,

I would like deleting specific characters from a string.
As an example, I would like to delete all of the '@' '&' in the
string 'You are ben@orange?ente r&your&code' so that it becomes
'benorange?ente ryourcode'.

So far I have been doing it like:
str = 'You are ben@orange?ente r&your&code'
str = ''.join([ c for c in str if c not in ('@', '&')])

but that looks so ugly.. I am hoping to see nicer examples to acheive
the above..

What about the following:

str = 'You are ben@orange?ente r&your&code'
str = filter(lambda c: c not in "@&", str) Aaack! I cringe seeing builtin str name rebound like that ;-/

Bye,
Walter Dörwald

def isAcceptableCha r(character):
return charachter in "@&"

return character not in "@&"
str = filter(isAccept ableChar, str)

is going to finally be what I am going to use. That's not going to be anywhere near as fast as Donn's translate version.
I not feel lambdas are so readable, unless one has serious experience in
using them and python in general. I feel it is acceptable to add a named
method that documents with its name what it is doing there.

But your example would probably have been my choice if I was more
familiar with that type of use and the potential readers of my code were
also familiar with it. Many thanks!
IMO, if you are going to define a function like isAcceptableCha r, only to use it
with filter, why not write a function to do the whole job, and whose invocation
reads well, while hiding Donn's fast translate version? E.g., substituting the literal
value of string.maketran s('',''):

====< removechars.py >============== =============== =============== ============
def removeChars(s, remove=''):
return s.translate(
'\x00\x01\x02\x 03\x04\x05\x06\ x07\x08\t\n\x0b \x0c\r\x0e\x0f'
'\x10\x11\x12\x 13\x14\x15\x16\ x17\x18\x19\x1a \x1b\x1c\x1d\x1 e\x1f'
' !"#$%&\'()*+ ,-./'
'0123456789:;<= >?'
'@ABCDEFGHIJKLM NO'
'PQRSTUVWXYZ[\\]^_'
'`abcdefghijklm no'
'pqrstuvwxyz{|} ~\x7f'
'\x80\x81\x82\x 83\x84\x85\x86\ x87\x88\x89\x8a \x8b\x8c\x8d\x8 e\x8f'
'\x90\x91\x92\x 93\x94\x95\x96\ x97\x98\x99\x9a \x9b\x9c\x9d\x9 e\x9f'
'\xa0\xa1\xa2\x a3\xa4\xa5\xa6\ xa7\xa8\xa9\xaa \xab\xac\xad\xa e\xaf'
'\xb0\xb1\xb2\x b3\xb4\xb5\xb6\ xb7\xb8\xb9\xba \xbb\xbc\xbd\xb e\xbf'
'\xc0\xc1\xc2\x c3\xc4\xc5\xc6\ xc7\xc8\xc9\xca \xcb\xcc\xcd\xc e\xcf'
'\xd0\xd1\xd2\x d3\xd4\xd5\xd6\ xd7\xd8\xd9\xda \xdb\xdc\xdd\xd e\xdf'
'\xe0\xe1\xe2\x e3\xe4\xe5\xe6\ xe7\xe8\xe9\xea \xeb\xec\xed\xe e\xef'
'\xf0\xf1\xf2\x f3\xf4\xf5\xf6\ xf7\xf8\xf9\xfa \xfb\xfc\xfd\xf e\xff'
, remove)

if __name__ == '__main__':
import sys
args = sys.argv[1:]
fin = sys.stdin; fout=sys.stdout ; remove='' # defaults
while args:
arg = args.pop(0)
if arg == '-fi': fin = file(args.pop(0 ))
elif arg == '-fo': fout = file(args.pop(0 ))
else: remove = arg
for line in fin:
fout.write(remo veChars(line, remove))
=============== =============== =============== =============== =============== ===
Not tested beyond what you see here ;-)

[16:40] C:\pywk\ut>echo "'You are ben@orange?ente r&your&code'" |python removechars.py "@&"
"'You are benorange?enter yourcode'"

[16:41] C:\pywk\ut>echo "'You are ben@orange?ente r&your&code'" |python removechars.py aeiou
"'Y r bn@rng?ntr&yr&c d'"

Copying a snip above to the clipboard and filtering that with no removes and then (lower case) vowels:

[16:41] C:\pywk\ut>getc lip |python removechars.pyI not feel lambdas are so readable, unless one has serious experience in
using them and python in general. I feel it is acceptable to add a named
method that documents with its name what it is doing there.

But your example would probably have been my choice if I was more
familiar with that type of use and the potential readers of my code were
also familiar with it. Many thanks!
[16:42] C:\pywk\ut>getc lip |python removechars.py aeiouI nt fl lmbds r s rdbl, nlss n hs srs xprnc n
sng thm nd pythn n gnrl. I fl t s ccptbl t dd nmd
mthd tht dcmnts wth ts nm wht t s dng thr.

Bt yr xmpl wld prbbly hv bn my chc f I ws mr
fmlr wth tht typ f s nd th ptntl rdrs f my cd wr
ls fmlr wth t. Mny thnks!

Regards,
Bengt Richter