zlib and gzip
Greg Bakken
strings from another piece of software. I can successfully uncompress
and decode the strings via
import base64, zlib
def getString(s):
s = base64.decodestring(s)
s = zlib.decompress(s, -15)
return s
Now, I want to take a 'readable' text string, and compress and encode
it the same way as the other piece of software. I first tried the
seemingly obvious (but incorrect)
import base64, zlib
def makeString(s):
s = zlib.compress(s, 9)
s = base64.encodestring(s)
return s
I have also tried using the gzip module to do this like
import base64, gzip, StringIO
def makeString(s):
sio = StringIO.StringIO()
gzipper = gzip.GzipFile(mode="wb", fileobj=sio)
gzipper.write(s)
s = base64.encodestring(sio.getvalue())
return s
What I would like to be able to do is take a string s, pass it through
the makeString function, and pass the result through the getString
function, and end up with the original string s back. I have to stick
with the way getString is, so I can handle strings from another
program, so I need to adapt makeString accordingly, but cannot figure
out how.
Greg
Hornberger, Chris
--------------------------
Chris Hornberger
Blackrock - 302.797.2318
chris.ho...@blackrock.com
Card carrying MSDN member since 2004.
No, really. I've got the card to prove it.
Hornberger, Chris
import base64, zlib
def getString(s):
s = base64.decodestring(s)
s = zlib.decompress(s ) #, -15)
return s
def makeString(s):
s = zlib.compress(s ) #, 9)
s = base64.encodestring(s)
return s
initialdata = "this is a test"
print "1)" + initialdata
compresseddata = makeString( initialdata )
print "2)" + compresseddata
uncompressed = getString( compresseddata )
print "3)" + uncompressed
and got the following results:
C:\>comp.py
1)this is a test
2)eJwrycgsVgCiRIWS1OISACYzBRY=
3)this is a test
C:\>
--------------------------
Chris Hornberger
Blackrock - 302.797.2318
chris.ho...@blackrock.com
Card carrying MSDN member since 2004.
No, really. I've got the card to prove it.
-----Original Message-----
From: python-list-bounces+chris.hornberger=blackr...@python.org
[mailto:python-list-bounces+chris.hornberger=blackr...@python.org]On
Behalf Of Hornberger, Chris
Sent: Wednesday, May 12, 2004 1:14 PM
To: Bakken, Gregory A; pytho...@python.org
Subject: RE: zlib and gzip
Ok, fair enough. Can you supply (if it's non-sensitive information) some samples?
I'm on this conference call for the next hour or so, so I'm glued to my desk. I have time to tinker. It's just a general status call. I just have to chime in from time to time.
--------------------------
Chris Hornberger
Blackrock - 302.797.2318
chris.ho...@blackrock.com
Card carrying MSDN member since 2004.
No, really. I've got the card to prove it.
-----Original Message-----
From: Bakken, Gregory A [mailto:gregory_...@groton.pfizer.com]
Sent: Wednesday, May 12, 2004 1:10 PM
To: Hornberger, Chris; pytho...@python.org
Subject: RE: zlib and gzip
The short answer is I don't know. The longer answer is that I really don't
know the driving force behind the compression/encoding that is being used.
What I am doing is a more downstream process (so I am stuck with the chosen
scheme).
Greg
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Bakken, Gregory A
Hornberger, Chris
I'm on this conference call for the next hour or so, so I'm glued to my desk. I have time to tinker. It's just a general status call. I just have to chime in from time to time.
--------------------------
Chris Hornberger
Blackrock - 302.797.2318
chris.ho...@blackrock.com
Card carrying MSDN member since 2004.
No, really. I've got the card to prove it.
-----Original Message-----
From: Bakken, Gregory A [mailto:gregory_...@groton.pfizer.com]
Sent: Wednesday, May 12, 2004 1:10 PM
Bakken, Gregory A
short, I have a text string in readable format, and compressed/encoded by
the other app. My getString function below can recover the original string
from what is provided by the other app. If I take the original string and
try to compress/encode and then recover it, both approaches I have tried
fail. (In other words, the script below will actually crash with an error
something like zlib.error: Error -3 while decompressing data: invalid block
type
import gzip, zlib, StringIO, base64
def getString(s):
s = base64.decodestring(s)
s = zlib.decompress(s, -15)
return s
def makeString1(s):
s = zlib.compress(s, 9)
s = base64.encodestring(s)
return s
def makeString2(s):
sio = StringIO.StringIO()
gzipper = gzip.GzipFile(mode="wb", fileobj=sio)
gzipper.write(s)
s = base64.encodestring(sio.getvalue())
return s
previouslyMadeString = "81RIzFVIVChKTUxJTMpJVSguKcrMSwcA"
readableString = "I am a readable string"
print "Original string"
print readableString
print ""
print "Decoded string form other program"
print getString(previouslyMadeString)
print ""
ms1 = makeString1(readableString)
gs1 = getString(ms1)
print "Decoded from appraoch 1"
print gs1
ms2 = makeString2(readableString)
gs2 = getString(ms2)
print "Decoded from appraoch 1"
print gs2
-----Original Message-----
From: Hornberger, Chris [mailto:Chris.Ho...@blackrock.com]
Sent: Wednesday, May 12, 2004 1:14 PM