Re: Turning a Sequence into a List?

*To*: mathgroup at smc.vnet.net*Subject*: [mg130516] Re: Turning a Sequence into a List?*From*: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>*Date*: Thu, 18 Apr 2013 05:33:15 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

Hello, I'm playing with a problem with minimum coins to make change. Here's a problem spot where I look at ways to make up 52 and 53 cents (later I'll use v = Range[1,99]. v=Range[52,53]; sol=(Reduce[25q+10d+5n+p==# &&0<=p<5 &&0<=n<2 &&0<=d<3 &&0<=q<4,{q,d,n,p},Integers])& /@v (* which gives {(q == 1 && d == 2 && n == 1 && p == 2) || (= q == 2 && d == 0 && n == 0 && p == 2), (q == 1 && d == 2 && n == 1 && p == 3) || (q == 2 && d == 0 && n == 0 && p == 3)}= *) There are two cases for each coin and I need to pick the one with the smallest number of coins. But the only way I know to begin that is with a list of rules. I can get a Sequence for the first element of the List sol but I can't figure how to get the Sequence to a list. x = (sol[[1]]) // ToRules (* Sequence[{q -> 1, d -> 2, n -> 1, p -> 2}, {q -> 2, d -> 0, n -> 0, p -> 2}] *) I've always had problems figuring out what a Sequence is and the HELP doesn't really help me. Can someone please suggest how I can use this sequence to select the {q,d,n,p} set that has the minimum coin count? It's got me stumped. Thanks. -- Hi, To turn this sq=Sequence[{q -> 1, d -> 2, n -> 1, p -> 2}, {q -> 2, d -> 0, n -> 0, p -> 2}]; into the list you may plainly write: lst1=List[sq] It returns {{q -> 1, d -> 2, n -> 1, p -> 2}, {q -> 2, d -> 0, n -> 0, p -> 2}} Now, if I understand you right, you would like to sort out a combination with the minimum sum q+d+n+p, would you? If yes, one way to do this is as follows: This removes the rules, but leaves instead the right part of each rule in the list: lst2 = lst1 /. Rule[x_, y_] -> y (* {{1, 2, 1, 2}, {2, 0, 0, 2}} *) This finds the position of the sublist with the minimal sum: pos = Position[Total[#] & /@ lst2, Min[Total[#] & /@ lst2]][[1, 1]] (* 2 *) And this returns the sublist of rules with the minimal sum: lst1[[pos]] (* {q -> 2, d -> 0, n -> 0, p -> 2} *) Have fun, Alexei Alexei BOULBITCH, Dr., habil. IEE S.A. ZAE Weiergewan, 11, rue Edmond Reuter, L-5326 Contern, LUXEMBOURG Office phone : +352-2454-2566 Office fax: +352-2454-3566 mobile phone: +49 151 52 40 66 44 e-mail: alexei.boulbitch at iee.lu