RE : Building List

*To*: mathgroup at smc.vnet.net*Subject*: [mg48033] RE : [mg48015] Building List*From*: "Florian Jaccard" <florian.jaccard at eiaj.ch>*Date*: Sat, 8 May 2004 01:23:37 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hello ! There are a lot of ways... For example : In[47]:= exemple = {{1, 2}, {3, 4, 5, 6}, {7, 8}, {9, 10, 11}}; In[52]:= Clear[f]; f[li_ /; Length[li] > 2] := ({First[li], #1} & ) /@ Drop[li, 1]; f[li_] := {li}; In[55]:= Flatten[f /@ exemple, 1] Out[55]= {{1, 2}, {3, 4}, {3, 5}, {3, 6}, {7, 8}, {9, 10}, {9, 11}} Meilleures salutations F.Jaccard -----Message d'origine----- De : Bruce W. Colletti [mailto:bcolletti at compuserve.com] Envoyé : vendredi, 7. mai 2004 10:30 À : mathgroup at smc.vnet.net Objet : [mg48015] Building List Re Mathematica 5.0.1.0. I have a list of lists -- e.g., L = { {1,2},{3,4,5,6},{7,8} } -- and want to replace element-lists (whose length exceeds 2) with another list built from that element. All else is untouched. For instance, using L above, replace {3,4,5,6} with {3,4}, {3,5}, {3,6}. This transforms L to the desired form { {1,2}, {3,4}, {3,5}, {3,6}, {7,8} }. Although I can do this using Sow and Reap, am hoping there's an easier way using rules (/.). In general, I want to replace those L-elements x (that meet a criterion) with foo[x]. Thanks. Bruce