Compress a string

[Matt Porter]

Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

The code I have so far feels like it could be made clearer and more
succinct, but a solution is currently escaping me.
def compress_str(str):
new_str = ""
for i, c in enumerate(str):
try:
if c != str[i+1]:
new_str += c
except IndexError:
new_str += c
return new_str
Cheers
Matt
--
--

[Salvatore DI DI0]

Try this

t = set("aaaaaaaaaaaabbbbbbbbbbccccccccc")
list(t)

Regards

Salvatore
"Matt Porter" <ma*******@gmail.coma écrit dans le message de news:
ma***************************************@python.o rg...

Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

The code I have so far feels like it could be made clearer and more
succinct, but a solution is currently escaping me.
def compress_str(str):
new_str = ""
for i, c in enumerate(str):
try:
if c != str[i+1]:
new_str += c
except IndexError:
new_str += c
return new_str
Cheers
Matt
--
--

[Arnaud Delobelle]

"Matt Porter" <ma*******@gmail.comwrites:

Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

The code I have so far feels like it could be made clearer and more
succinct, but a solution is currently escaping me.
def compress_str(str):
new_str = ""
for i, c in enumerate(str):
try:
if c != str[i+1]:
new_str += c
except IndexError:
new_str += c
return new_str
Cheers
Matt
--
--

>>string = 'sssssssssspppppppaaaaaaam'
''.join(x for x, y in zip(string, '\0'+string) if x != y)

'spam'

HTH

PS: I keep seeing problems on this list whose solution seems to
involve 'window' iterating over a sequence. E.g.

>>list(window('eggs', 2))

[('e', 'g'), ('g', 'g'), ('g', 's')]

--
Arnaud

[Peter Otten]

Matt Porter wrote:

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

Two more:

>>from itertools import groupby
"".join(k for k, g in groupby("aaaaaabbbbbbbbbbcccccc"))

'abc'

>>import re
re.compile(r"(.)\1*").sub(r"\1", "aaaaaaabbbbcccccccc")

'abc'

Peter

[Marc Christiansen]

Matt Porter <ma*******@gmail.comwrote:

Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

You mean like this?

>>''.join(c for c, _ in itertools.groupby("AAAABBBCAADCASS"))

'ABCADCAS'

HTH
Marc

[Matt Porter]

On Sun, 18 May 2008 20:30:57 +0100, Peter Otten <__*******@web.dewrote:

Matt Porter wrote:

>I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

Two more:

>>>from itertools import groupby
"".join(k for k, g in groupby("aaaaaabbbbbbbbbbcccccc"))

'abc'

>>>import re
re.compile(r"(.)\1*").sub(r"\1", "aaaaaaabbbbcccccccc")

'abc'

Brilliant - I was trying to figure out how to do this with the re
capabilities.

Thanks to everyone

Peter
--
http://mail.python.org/mailman/listinfo/python-list

--
--

[inhahe]

i see lots of neat one-liner solutions but just for the sake of argument:

def compress_str(str):
new_str = ""
lc = ""
for c in str:
if c != lc: new_str.append(c)
return new_str
"Matt Porter" <ma*******@gmail.comwrote in message
news:ma***************************************@pyt hon.org...

Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

The code I have so far feels like it could be made clearer and more
succinct, but a solution is currently escaping me.


Cheers
Matt
--
--

[Bjoern Schliessmann]

inhahe wrote:

i see lots of neat one-liner solutions but just for the sake of
argument:

def compress_str(str):
new_str = ""
lc = ""
for c in str:
if c != lc: new_str.append(c)
return new_str

Please test before posting.

>>compress_str("AAAABBBBCCCCC")

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 5, in compress_str
AttributeError: 'str' object has no attribute 'append'

Regards,
Björn

--
BOFH excuse #48:

bad ether in the cables

[John Salerno]

On Sun, 18 May 2008 19:06:10 +0100
"Matt Porter" <ma*******@gmail.comwrote:

Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

Not that you need help anymore, but I decided to give it a try. Not as elegant as the one- and two-liners, but somewhat concise I guess.

def compress(s):
new = [s[:1]]

for c in s[1:]:
if c not in new:
new.append(c)
return ''.join(new)

[John Salerno]

On Tue, 20 May 2008 00:09:14 -0400
John Salerno <jo******@NOSPAMgmail.comwrote:

Not that you need help anymore, but I decided to give it a try. Not as elegant as the one- and two-liners, but somewhat concise I guess.

Whoops! Could be cleaner! :)

def compress(s):
new = []

for c in s:
if c not in new:
new.append(c)
return ''.join(new)
No, wait! I can do better!

def compress(s):
new = []
[new.append(c) for c in s if c not in new]
return ''.join(new)

Wow, list comprehensions are cool.

[Marc 'BlackJack' Rintsch]

On Tue, 20 May 2008 00:38:57 -0400, John Salerno wrote:

def compress(s):
new = []

for c in s:
if c not in new:
new.append(c)
return ''.join(new)
No, wait! I can do better!

def compress(s):
new = []
[new.append(c) for c in s if c not in new] return ''.join(new)

Wow, list comprehensions are cool.

And it's a misuse of list comprehension here IMHO because they are meant to
build lists, not to cram a ``for``/``if`` loop into a one liner. You are
building a list full of `None` objects, just to throw it away.

Ciao,
Marc 'BlackJack' Rintsch

[Bruno Desthuilliers]

Salvatore DI DI0 a écrit :
(top-post corrected - Salvatore, please, don't top-post)

"Matt Porter" <ma*******@gmail.coma écrit dans le message de news:
ma***************************************@python.o rg...

>Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

Try this

t = set("aaaaaaaaaaaabbbbbbbbbbccccccccc")
list(t)

Won't keep the ordering.

[Bruno Desthuilliers]

Matt Porter a écrit :

Hi guys,

I'm trying to compress a string.
E.g:
"AAAABBBC" -"ABC"

The code I have so far feels like it could be made clearer and more
succinct, but a solution is currently escaping me.
def compress_str(str):

using 'str' as an indentifier will shadow the builtin str type.

new_str = ""
for i, c in enumerate(str):
try:
if c != str[i+1]:
new_str += c
except IndexError:
new_str += c
return new_str

Now everyone gave smart solutions, may I suggest the stupidier possible one:

def compress_string(astring):
compressed = []
for c in astring:
if c not in compressed:
compressed.append(c)
return ''.join(compressed)

Not elegant, but at least very clear.