extracting elements from a list of lists

*To*: mathgroup at smc.vnet.net*Subject*: [mg5811] extracting elements from a list of lists*From*: Olivier Georg <olivier.georg at studi.epfl.ch>*Date*: Wed, 22 Jan 1997 00:44:15 -0500*Organization*: EPF Lausanne*Sender*: owner-wri-mathgroup at wolfram.com

Hi, Suppose I have lists within a list, like: myList = {{a,b}, {c,d}} and I want to extract some element (let's say the d). I can request: myList[[2,2]]. Now suppose what I have the index of the element as the list {2,2}. Then I can do: Fold[Part, myList, {2,2}] Is it correct to suppose that it will first return the 2nd sublist, and then extract the second element from it? How efficient is it? This may be a crucial point if I have long lists, I think. Then isn't there a better way of doing this? Olivier -- ------------------------------------------------------------------- | Olivier Georg \__ e-mail: Olivier.Georg at studi.epfl.ch | | Rte de Chailly 159 \__ home: http://diwww.epfl.ch/~ogeorg | | 1814 La Tour-de-Peilz \__ tel: +41 21 944 15 42 | ------------------------------\__---------------------------------- | On ne peut pas tuer le temps \__ | | Sans blesser un peu l'eternite \__ ________ __o | | ( As if you could kill time ) \__ _____ _`\<,_ | | ( without injuring eternity. ) \__ ___ (_)/ (_) | | Henry David Thoreau \ | -------------------------------------------------------------------