Re: i don't understand mapping function over a long list

*To*: mathgroup at smc.vnet.net*Subject*: [mg47819] Re: i don't understand mapping function over a long list*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 28 Apr 2004 06:56:01 -0400 (EDT)*Organization*: Universitaet Leipzig*References*: <c6l7v9$iq0$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de*Sender*: owner-wri-mathgroup at wolfram.com

Hi, a) you can't get {{x$299, x$300, x$301} + 2,..} because Mathematica will distribute the scalar addition over the lists an you will always end with {{x$299+2, x$300+2, x$301+2},..} b) you can use an new symbol that is not a List with l = vector @@@ Partition[Flatten[{Table[Unique[x], {n, 1, 30}]}], 3]; and l+2 c) you can assign the result to unames = Table[Unique[u], {10}]; with Set @@@ Transpose[{unames, (l + 2)}] Regards Jens will produce the desired result. sean kim wrote: > > hello group. > > i just don't get this. > > I'm not sure what's the problem is. > > please consider the following list of lists. > > l = Partition[Flatten[{Table[Unique[x], {n, 1, 30}]}], 3 ] > > above generates a list of 10 lists with 3 elements in each as in... > > { > {x$299, x$300, x$301}, {x$302, x$303, x$304}, > {x$305, x$306, x$307}, {x$308, x$309, x$310}, > {x$311, x$312, x$313}, {x$314, x$315, x$316}, > {x$317, x$318, x$319}, {x$320, x$321, x$322}, > {x$323, x$324, x$325}, {x$326, x$327, x$328} > } > > Now suppose I want to use each of the list( all 10 of them) as a part > of a function. . I want to "Apply" the function to every list(so, 10 > times in total) > for a simple examplel let's add 2 to the lists > > In[21]:= Apply[Plus@@xlist, 2] > Out[21]= 2 > > that didn't work. i wanted to get was > > {{x$299, x$300, x$301} + 2, > {x$302, x$303, x$304} + 2... > {x$326, x$327, x$328} + 2}} > > then i want to give each of the results unique names and use the > renamed list of lists as an argument in another function. > > { > uniquexname1 = {x$299, x$300, x$301} + 2, > uniquexname2 = {x$302, x$303, x$304} + 2... > uniquexname10 = {x$326, x$327, x$328} + 2} > } > > and > > Map[Plus, xlist, 2] > > just bring back the list itself. > > This problem recurs for me. and I think i have problems with it > because I just don't understand how Mathematica language works. > > Reading the book an dhelp manual doesn't help me much in understanding > what lies underneath. Can you guys shed soem light on this with some > simple examples that use numerical operations? > > Maybe I'm asking a lot, but any and all insights are thoroughly > appreciated. > > thanks in advance. > > sean