Re: Average the same elements of the list
- To: mathgroup at smc.vnet.net
- Subject: [mg130881] Re: Average the same elements of the list
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Thu, 23 May 2013 04:08:17 -0400 (EDT)
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You didn't specify what to return in case the first elements of the sublists are NOT all the same; let's return the entire original list in this case. Then perhaps something like the following will do. op[lis_] := If[And @@ MapThread[Equal, First /@ lis], {First@First@lis, Mean[Last /@ lis]}, lis] op[{ {{2, 5, -1}, d1}, {{2, 5, -1}, d2}}] (* { {2, 5, -1}, (d1 + d2)/2 } *) op[{{{2, 5, -1}, d1}, {{2, 9, -1}, d2}}] (* {{{2, 5, -1}, d1}, {{2, 9, -1}, d2}} *) Undoubtedly the code can be shortened. On May 22, 2013, at 2:18 AM, BBabic <bipsich101 at gmail.com> wrote: > Hello, > I have list which is something like > data={ > {{a1,b1,c1},d1},{{a2,b2,c2},d2}} > I would like to get new list which gets average of the second elements if the first elements in the sublists are all the same. > Namely if a1=a2,b1=b2,c1=c2 > new list would look like > datanew={{a1,b1,c1},Mean[{d1,d2}] > Is there an elegant way to do this ? > Thanks! --- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2838 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305
- References:
- Average the same elements of the list
- From: BBabic <bipsich101@gmail.com>
- Average the same elements of the list