[vox-tech] [OT] Binary Representation Challenge

[Alex Mandel]

Micah J. Cowan wrote:
> On Tue, Sep 20, 2005 at 12:02:26PM -0700, Alex Mandel wrote:
> 
>>I realize this might be not be a challenge for some of you.
>>--
>>I need to make a list of all possible permutations given 9 options and 
>>that you can choose any number of options at once.
>>I've figured out using nCr statistics that this is 511 choices, but now 
>>I need to represent them in 2^9 binary code: 000000001, 000000010 etc
>>
>>Anyone got a quick way? I thought about writing a python code or 
>>something but then I got confused just thinking about the algorthim.
>>
>>Now the best would be if you had an idea that I could implement with my 
>>limited toolset: R, OpenOffice, Python, and I guess I could add a 
>>package to Cygwin if necessary.
> 
> 
> Perhaps its simpler than you think?
> 
> If all you need is the different permutations of two-choice options, all
> of which can be selected in any combination, then this is exactly the
> same as counting in binary.
> 
> Or is it actually printing the representation of the binary that is
> posing a problem?

Correct, I need to print a list to represent the choices.
It's going to be a lookup table in a database on the backside of a 
webpage that pulls up a static map of the options picked.

> FWIW, Knuth has recently published a couple of fascicles from Volume IV
> of TAOCP; both of them dealing with "Generating all Tuples and
> Permutations". I was stumped by how much there is to know about such a
> seemingly simple subject.
> 
> -Micah
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Thanks- Alex