On Oct 17, 4:58 pm, Ixiaus <[EMAIL PROTECTED]> wrote: > Thank you for the quick responses. > > I did not know that about integer literals beginning with a '0', so > thank you for the explanation. I never really use PHP except for > handling basic forms and silly web stuff, this is why I picked up > Python because I want to teach myself a more powerful and broad > programming language. > > With regard to why I asked: I wanted to learn about Binary math in > conjunction with Python, so I wrote a small function that would return > a base 10 number from a binary number. It is nice to know about the > int() function now. > > Just for the sake of it, this was the function I came up with: > > def bin2dec(val): > li = list(val) > li.reverse() > res = [int(li[x])*2**x for x in range(len(li))] > res.reverse() > print sum(res) > > Now that I look at it, I probably don't need that last reverse() > because addition is commutative... > > def bin2dec(val): > li = list(val) > li.reverse() > res = [int(li[x])*2**x for x in range(len(li))] > print sum(res) > > It basically does the same thing int(string, 2) does. > > Thank you for the responses!
You could also get ahold of the gmpy module. You get conversion to binary and also some useful other binary functions as shown below: # the Collatz Conjecture in binary import gmpy n = 27 print '%4d %s' % (n,gmpy.digits(n,2).zfill(16)) sv = [] # sequence vector, blocks of contiguous LS 0's while n != 1: old_n = n n = 3*n + 1 # result always even f = gmpy.scan1(n,0) # find least significant 1 bit n >>= f # remove LS 0's in one fell swoop sv.append(f) # record f sequence PopC = gmpy.popcount(n) # count of 1 bits HamD = gmpy.hamdist(n,old_n) # bits changed print '%4d %s' % (n,gmpy.digits(n,2).zfill(16)), print 'PopC:%2d HamD:%2d' % (PopC,HamD) print sv ## 27 0000000000011011 ## 41 0000000000101001 PopC: 3 HamD: 3 ## 31 0000000000011111 PopC: 5 HamD: 4 ## 47 0000000000101111 PopC: 5 HamD: 2 ## 71 0000000001000111 PopC: 4 HamD: 3 ## 107 0000000001101011 PopC: 5 HamD: 3 ## 161 0000000010100001 PopC: 3 HamD: 4 ## 121 0000000001111001 PopC: 5 HamD: 4 ## 91 0000000001011011 PopC: 5 HamD: 2 ## 137 0000000010001001 PopC: 3 HamD: 4 ## 103 0000000001100111 PopC: 5 HamD: 6 ## 155 0000000010011011 PopC: 5 HamD: 6 ## 233 0000000011101001 PopC: 5 HamD: 4 ## 175 0000000010101111 PopC: 6 HamD: 3 ## 263 0000000100000111 PopC: 4 HamD: 4 ## 395 0000000110001011 PopC: 5 HamD: 3 ## 593 0000001001010001 PopC: 4 HamD: 7 ## 445 0000000110111101 PopC: 7 HamD: 7 ## 167 0000000010100111 PopC: 5 HamD: 4 ## 251 0000000011111011 PopC: 7 HamD: 4 ## 377 0000000101111001 PopC: 6 HamD: 3 ## 283 0000000100011011 PopC: 5 HamD: 3 ## 425 0000000110101001 PopC: 5 HamD: 4 ## 319 0000000100111111 PopC: 7 HamD: 4 ## 479 0000000111011111 PopC: 8 HamD: 3 ## 719 0000001011001111 PopC: 7 HamD: 3 ##1079 0000010000110111 PopC: 6 HamD: 7 ##1619 0000011001010011 PopC: 6 HamD: 4 ##2429 0000100101111101 PopC: 8 HamD: 8 ## 911 0000001110001111 PopC: 7 HamD: 7 ##1367 0000010101010111 PopC: 7 HamD: 6 ##2051 0000100000000011 PopC: 3 HamD: 6 ##3077 0000110000000101 PopC: 4 HamD: 3 ## 577 0000001001000001 PopC: 3 HamD: 5 ## 433 0000000110110001 PopC: 5 HamD: 6 ## 325 0000000101000101 PopC: 4 HamD: 5 ## 61 0000000000111101 PopC: 5 HamD: 5 ## 23 0000000000010111 PopC: 4 HamD: 3 ## 35 0000000000100011 PopC: 3 HamD: 3 ## 53 0000000000110101 PopC: 4 HamD: 3 ## 5 0000000000000101 PopC: 2 HamD: 2 ## 1 0000000000000001 PopC: 1 HamD: 1 ##[1, 2, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 2, ## 1, 1, 1, 2, 3, 1, 1, 2, 1, 2, 1, 1, 1, ## 1, 1, 3, 1, 1, 1, 4, 2, 2, 4, 3, 1, 1, ## 5, 4] -- http://mail.python.org/mailman/listinfo/python-list
