Comments on: Just for fun: binary to ascii in Python http://gehrcke.de/2010/01/just-for-fun-binary-to-ascii-in-python/ Jan-Philip Gehrcke's website Tue, 13 Sep 2011 22:01:14 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Jan-Philip Gehrckehttp://gehrcke.de/2010/01/just-for-fun-binary-to-ascii-in-python/comment-page-1/#comment-6319 Jan-Philip Gehrcke Tue, 13 Sep 2011 22:01:14 +0000 http://gehrcke.de/?p=1118#comment-6319 A quick benchmark to compare both methods...: <pre lang="python"> #!/usr/bin/python import random import time import hashlib bitlength = 8 N = 2**21 s = N * [0] s.extend(N * [1]) random.shuffle(s) # now s is a list of ints 0, 1 (randomly ordered) ss = ''.join(map(str, s)) # a string from the same list t1 = time.time() rs = ''.join([chr(sum(bit<<abs(idx-bitlength)-1 for idx,bit in enumerate(y))) for y in zip(*[s[x::bitlength] for x in range(bitlength)])]) t2 = time.time() dt = t2-t1 print "hash method 1: %s" % hashlib.md5(rs).hexdigest() print "time method 1: %s" % dt t1 = time.time() rs = ''.join([chr(eval('0b'+ss[i:i+8])) for i in range(0, len(ss), bitlength)]) t2 = time.time() dt = t2-t1 print "hash method 2: %s" % hashlib.md5(rs).hexdigest() print "time method 2: %s" % dt </pre> Result: <pre lang="text"> $ ./bench.py hash method 1: 519e71070a5eb53fa4294b39845fb6a6 time method 1: 2.73728394508 hash method 2: 519e71070a5eb53fa4294b39845fb6a6 time method 2: 4.78630614281 </pre> So your method is almost half as fast. From more tests it looks like both methods scale the same with increasing <code>N</code>. I guess the <code>eval()</code> method is slow. Thanks for your comment anyway :) JP A quick benchmark to compare both methods…:

#!/usr/bin/python
import random
import time
import hashlib
bitlength = 8
N = 2**21
s = N * [0]
s.extend(N * [1])
random.shuffle(s) # now s is a list of ints 0, 1 (randomly ordered)
ss = ''.join(map(str, s)) # a string from the same list
t1 = time.time()
rs = ''.join([chr(sum(bit< 
Result: 
$ ./bench.py
hash method 1: 519e71070a5eb53fa4294b39845fb6a6
time method 1: 2.73728394508
hash method 2: 519e71070a5eb53fa4294b39845fb6a6
time method 2: 4.78630614281

So your method is almost half as fast. From more tests it looks like both methods scale the same with increasing N. I guess the eval() method is slow.

Thanks for your comment anyway :)

JP

]]> By: dennyshttp://gehrcke.de/2010/01/just-for-fun-binary-to-ascii-in-python/comment-page-1/#comment-6318 dennys Tue, 13 Sep 2011 21:24:54 +0000 http://gehrcke.de/?p=1118#comment-6318 for i in range(0,len(s),8): print chr(eval('0b'+s[i:i+8])), for i in range(0,len(s),8): print chr(eval(’0b’+s[i:i+8])),

]]>