Re: [Boost-users] generate structs with all combinations of members from a given struct - Boost-users - lists.preview.boost.org

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Re: [Boost-users] generate structs with all combinations of members from a given struct

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Hicham Mouline

1 Feb 2010 1 Feb '10

9:08 a.m.

----- Original Message ----- From: Hicham Mouline To: boost-users@lists.boost.org Sent: Monday, February 01, 2010 12:09 PM Subject: Re: [Boost-users] generate structs with all combinations of members from a given struct My previous runtime solution was wrong. I just fixed it now. #include <iostream> #include <list> typedef std::list< std::list > main_list_t; void combinations(main_list_t& m, const size_t* arr, size_t arrsize) { if (arrsize==0) return; const std::list empty_list; std::list l( m.empty()? empty_list: m.back() ); for (size_t s=0; s

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Larry Evans

1 Feb 1 Feb

7:35 p.m.

New subject: generate structs with all combinations of members from a given struct

On 02/01/10 03:08, Hicham Mouline wrote:

----- Original Message ----- *From:* Hicham Mouline mailto:hicham@mouline.org *To:* boost-users@lists.boost.org mailto:boost-users@lists.boost.org *Sent:* Monday, February 01, 2010 12:09 PM *Subject:* Re: [Boost-users] generate structs with all combinations of members from a given struct

My previous runtime solution was wrong. I just fixed it now.

I had a hard time understanding how it worked. A simpler solution would be to just generate the characteristic functions for sets of a given size. The characteristic function could then be used to select elements from the set: http://en.wikipedia.org/wiki/Characteristic_function The structure of such a program is very similar to yours in that it has a recursive call and a for loop. However, with this method, the for loop just has size 2. The depth of recursion is n, where n is size of the set. I think your method had recursion depth of n-1. The attached illustrates the method. Output is: size=32 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 0 0 0 1 0 0 1 0 1 0 0 0 1 1 0 0 1 1 1 0 0 0 0 0 1 0 1 0 0 1 0 0 1 0 1 0 1 1 0 1 0 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0 1 1 1 1 0 0 0 0 0 1 1 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 0 1 0 1 1 0 1 0 1 0 1 1 0 1 1 1 1 0 1 0 0 0 1 1 1 0 0 1 1 0 1 0 1 1 1 1 0 1 1 0 0 1 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1 -regards, Larry

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Larry Evans

7:59 p.m.

New subject: missing characteristic functions attachment was(Re: generate structs with all combinations of members from a given struct

On 02/01/10 13:35, Larry Evans wrote: [snip]

The attached illustrates the method. [snip] OOPS. Forgot to attach it. It's attached here.

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Hicham Mouline

2 Feb 2 Feb

1:51 a.m.

New subject: generate structs with all combinations of members from a given struct

----- Original Message ----- From: "Larry Evans" To: Sent: Tuesday, February 02, 2010 2:35 AM Subject: Re: [Boost-users] generate structs with all combinations of members from a given struct

On 02/01/10 03:08, Hicham Mouline wrote:

...
----- Original Message ----- *From:* Hicham Mouline mailto:hicham@mouline.org *To:* boost-users@lists.boost.org mailto:boost-users@lists.boost.org *Sent:* Monday, February 01, 2010 12:09 PM *Subject:* Re: [Boost-users] generate structs with all combinations of members from a given struct My previous runtime solution was wrong. I just fixed it now.

I had a hard time understanding how it worked. A simpler solution would be to just generate the characteristic functions for sets of a given size. The characteristic function could then be used to select elements from the set:

http://en.wikipedia.org/wiki/Characteristic_function

The structure of such a program is very similar to yours in that it has a recursive call and a for loop. However, with this method, the for loop just has size 2. The depth of recursion is n, where n is size of the set. I think your method had recursion depth of n-1.

The attached illustrates the method. Output is:

size=32 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 0 0 0 1 0 0 1 0 1 0 0 0 1 1 0 0 1 1 1 0 0 0 0 0 1 0 1 0 0 1 0 0 1 0 1 0 1 1 0 1 0 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0 1 1 1 1 0 0 0 0 0 1 1 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 0 1 0 1 1 0 1 0 1 0 1 1 0 1 1 1 1 0 1 0 0 0 1 1 1 0 0 1 1 0 1 0 1 1 1 1 0 1 1 0 0 1 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1

-regards, Larry

Yes, all this just became clear to me last night in a dream:-) Thanks,

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Diederick C. Niehorster

2:31 a.m.

New subject: generate structs with all combinations of members from a given struct

Potentially off-topic as I haven't followed this thread, but you can get that sequence as well by taking the binary representation of 0 till 31. The order of the elements would be different, but if that matters, you can simply flip the array from left to right, over the column dimension. MATLAB: b=dec2bin([0:31].') = 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111 fliplr(b) = 00000 10000 01000 11000 00100 10100 01100 11100 00010 10010 01010 11010 00110 10110 01110 11110 00001 10001 01001 11001 00101 10101 01101 11101 00011 10011 01011 11011 00111 10111 01111 11111 Best, Dee On Tue, Feb 2, 2010 at 9:51 AM, Hicham Mouline wrote:

----- Original Message ----- From: "Larry Evans" To: Sent: Tuesday, February 02, 2010 2:35 AM Subject: Re: [Boost-users] generate structs with all combinations of members from a given struct

...
On 02/01/10 03:08, Hicham Mouline wrote:

...
----- Original Message ----- *From:* Hicham Mouline mailto:hicham@mouline.org *To:* boost-users@lists.boost.org mailto:boost-users@lists.boost.org *Sent:* Monday, February 01, 2010 12:09 PM *Subject:* Re: [Boost-users] generate structs with all combinations of members from a given struct My previous runtime solution was wrong. I just fixed it now.

I had a hard time understanding how it worked. A simpler solution would be to just generate the characteristic functions for sets of a given size. The characteristic function could then be used to select elements from the set:

http://en.wikipedia.org/wiki/Characteristic_function

The structure of such a program is very similar to yours in that it has a recursive call and a for loop. However, with this method, the for loop just has size 2. The depth of recursion is n, where n is size of the set. I think your method had recursion depth of n-1.

The attached illustrates the method. Output is:

size=32 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 0 0 0 1 0 0 1 0 1 0 0 0 1 1 0 0 1 1 1 0 0 0 0 0 1 0 1 0 0 1 0 0 1 0 1 0 1 1 0 1 0 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0 1 1 1 1 0 0 0 0 0 1 1 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 0 1 0 1 1 0 1 0 1 0 1 1 0 1 1 1 1 0 1 0 0 0 1 1 1 0 0 1 1 0 1 0 1 1 1 1 0 1 1 0 0 1 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1

-regards, Larry

Yes, all this just became clear to me last night in a dream:-)

Thanks, _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Diederick C. Niehorster
Hicham Mouline
Larry Evans