4

I have this text :

2,3,5,1,13,7,17,11,89,1,233,29,61,47,1597,19,37,41,421,199,28657,23,3001,521,53,281,514229,31,557,2207,19801,3571,141961,107,73,9349,135721,2161,2789,211,433494437,43,109441,139,2971215073,1103,97,101,6376021,90481,953,5779,661,14503,797,59,353,2521,4513,3010349,35239681,1087,14736206161,9901,269,67,137,71,6673,103681,9375829,54018521,230686501,29134601,988681,79,157,1601,2269,370248451,99194853094755497,83,9521,6709,173,263,1069,181,741469,4969,4531100550901,6643838879,761,769,193,599786069,197,401,743519377,919,519121,103,8288823481,119218851371,1247833,11128427,827728777,331,1459000305513721,10745088481,677,229,1381,347,29717,709,159512939815855788121,

This are numbers generated from my generator program,now the problem has a source code limit so I can't use the above texts in my solution so I want to compress this and put it into a data-structure in python so that I can print them by indexing like:

F = [`compressed data`]

and F[0] would give 2 F[5] would give 7 like this ... Please suggest me a suitable compression technique.

PS: I am a very newbie to python so please explain your method.

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6
  • 4
    I don't see any compression here. Are you sure that's the word you mean? Commented Jan 30, 2011 at 19:20
  • 1
    compression? that doesn't mean what you think it means. Commented Jan 30, 2011 at 19:20
  • What's the size of your number list? How fast do you need to get number for an index? Does this number list has any boundaries, properties, characteristics or any other information about number sequence? You say that you have source code limit. What is it? Do you have any memory limit? There are various compressing algorithms and the right choice depends on your restrictions and available information. Commented Jan 30, 2011 at 19:42
  • Given a value of N I have output the value of F[N] now the initialization of F[] should be such that F = [ 2,3,5,1,13,7,17,11,89,1,233,...] but instead of numbers I have use the compressed value so that the overall source code limit suffices. Commented Jan 30, 2011 at 19:57
  • @Tretwick Marian: Can you elaborate more what you mean by the problem has a source code limit and can't use the above texts in my solution. Are you participating to some kind of coding competition? Btw have you considered to just save the 'text' to a file and read it later when needed to a list? Commented Jan 30, 2011 at 20:29

3 Answers 3

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10

Sure you can do this:

import base64
import zlib
compressed = 'eJwdktkNgDAMQxfqR+5j/8V4QUJQUttx3Nrzl0+f+uunPPpm+Tf3Z/tKX1DM5bXP+wUFA777bCob4HMRfUk14QwfDYPrrA5gcuQB49lQQxdZpdr+1oN2bEA3pW5Nf8NGOFsR19NBszyX7G2raQpkVUEBdbTLuwSRlcDCYiW7GeBaRYJrgImrM3lmI/WsIxFXNd+aszXoRXuZ1PnZRdwKJeqYYYKq6y1++PXOYdgM0TlZcymCOdKqR7HYmYPiRslDr2Sn6C0Wgw+a6MakM2VnBk6HwU6uWqDRz+p6wtKTCg2WsfdKJwfJlHNaFT4+Q7PGfR9hyWK3p3464nhFwpOd7kdvjmz1jpWcxmbG/FJUXdMZgrpzs+jxC11twrBo3TaNgvsf8oqIYwT4r9XkPnNC1XcP7qD5cW7UHSJZ3my5qba+ozncl5kz8gGEEYOQ'
data = zlib.decompress(base64.b64decode(compressed))

Note that this is only 139 characters shorter. But it works:

>>> data
'2,3,5,1,13,7,17,11,89,1,233,29,61,47,1597,19,37,41,421,199,28657,23,3001,521,53,281,514229,31,557,2207,19801,3571,141961,107,73,9349,135721,2161,2789,211,433494437,43,109441,139,2971215073,1103,97,101,6376021,90481,953,5779,661,14503,797,59,353,2521,4513,3010349,35239681,1087,14736206161,9901,269,67,137,71,6673,103681,9375829,54018521,230686501,29134601,988681,79,157,1601,2269,370248451,99194853094755497,83,9521,6709,173,263,1069,181,741469,4969,4531100550901,6643838879,761,769,193,599786069,197,401,743519377,919,519121,103,8288823481,119218851371,1247833,11128427,827728777,331,1459000305513721,10745088481,677,229,1381,347,29717,709,159512939815855788121,'

If your code limit really is so short, maybe you are supposed to calculate this data or something? What is it?

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6 Comments

And how did you get the compressed value programatically ? :)
I did the same thing, but in reverse.
Okay let me try to rephrase :) I want to know how you obtain the compressed value in that format ? since something like this ideone.com/EDftR is not giving me that value.
Yeah, I said reverse. You obviously have to reverse the order of the actions, ie base64.b64encode(zlib.compress(s))
I have up-voted this one :) Now I understand both of the solutions :)
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5

zlib would get the job done, if you indeed want compression. If you don't want compression, then I'm afraid that my mind-reading skills are on the wane.

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11 Comments

gzip + base64 may indeed have smaller size than the source text. I just tried to do that with the digits presented, and it compressed the text from 663 to 475 bytes. Not stellar, though.
I guess this is what I am looking for but I am new to pyth so could please explain the compression and decompression technique ?
@Tretwick Compressing makes it take up less space. zlib is lossless compression so no information is lost. Decompression is the inverse operation. Did you read the link I included in my answer?
Yes I did,say I want to compress a text 'My name is Tretwick' hence I write zlib.compress('My name is Tretwick') but then I have to print it and then to get the compressed data back to get the original I have to use zlib.decompress() but when I print it it give me some different things which is not working if I copy paste into the decompress module. I hope you get my point.
@Tretwick I guess you're doing it wrong somehow, but I don't know off the top of my head. The simple compress/decompress cycle you propose works fine for me.
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2

On Python 2.4-2.7, pypy, jython:

>>> enc = sdata.encode('zlib').encode('base64')
>>> print enc
eJwdktkNgDAMQxfqR+5j/8V4QUJQUttx3Nrzl0+f+uunPPpm+Tf3Z/tKX1DM5bXP+wUFA777bCob
4HMRfUk14QwfDYPrrA5gcuQB49lQQxdZpdr+1oN2bEA3pW5Nf8NGOFsR19NBszyX7G2raQpkVUEB
dbTLuwSRlcDCYiW7GeBaRYJrgImrM3lmI/WsIxFXNd+aszXoRXuZ1PnZRdwKJeqYYYKq6y1++PXO
YdgM0TlZcymCOdKqR7HYmYPiRslDr2Sn6C0Wgw+a6MakM2VnBk6HwU6uWqDRz+p6wtKTCg2WsfdK
JwfJlHNaFT4+Q7PGfR9hyWK3p3464nhFwpOd7kdvjmz1jpWcxmbG/FJUXdMZgrpzs+jxC11twrBo
3TaNgvsf8oqIYwT4r9XkPnNC1XcP7qD5cW7UHSJZ3my5qba+ozncl5kz8gGEEYOQ
>>> print enc.decode('base64').decode('zlib')[:79]
2,3,5,1,13,7,17,11,89,1,233,29,61,47,1597,19,37,41,421,199,28657,23,3001,521,53
>>> sdata == enc.decode('base64').decode('zlib')
True
>>> F = [int(s) for s in sdata.split(',') if s.strip()]
>>> F[0], F[5]
(2, 7)
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