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MathGroup Archive 2007

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Re: averaging sublists of different lengths

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75508] Re: [mg75466] averaging sublists of different lengths
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Thu, 3 May 2007 03:50:22 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

colMeans[data_]:=Module[{n=Max[Length/@data],z},
      Mean[Cases[#,_?NumericQ]]&/@
        Transpose[(PadRight[#,n,z]&/@data)]];

data={{70,66,64,68,64,56,68,78,62,68,84},
      {70,64,64,56,66,56,62,64,66,88,54,72},
      {58,54,54,60,72,70,62,68,74,76,70},
      {66,56,60,64,56,62,68,58,58,58,68,76,62,76,66,64,
      88,56},{56,64,72,72,70,62,76,76,76,76,86,80,100},
      {60,60,70,68,60,60,50,56,60,70,62,68,88,84,82},
      {54,66,72,62,70,66,70,56},
      {60,60,60,62,74,80,70},
      {54,62,64,72,76,74},
      {66,74,70,80,54,54,64},
      {72,66,60,52,52,66,66,58,60,66}};

colMeans[data]

{686/11, 692/11, 710/11, 716/11, 714/11, 706/11, 328/5, 257/4, 456/7, 502/7, 212/3, 74, 250/3, 80, 74, 64, 88, 
  56}


Bob Hanlon

---- dantimatter <dantimatter at gmail.com> wrote: 
> 
> Hello all,
> 
> I have a list of lists like this:
> 
> {{70, 66, 64, 68, 64, 56, 68, 78, 62, 68, 84}, {70, 64, 64, 56, 66,
> 56, 62,
>     64, 66, 88, 54, 72}, {58, 54, 54, 60, 72, 70, 62, 68, 74, 76, 70},
> {66,
>     56, 60, 64, 56, 62, 68, 58, 58, 58, 68, 76, 62, 76, 66, 64, 88,
> 56}, {56,
>     64, 72, 72, 70, 62, 76, 76, 76, 76, 86, 80, 100}, {60, 60, 70, 68,
> 60, 60,
>      50, 56, 60, 70, 62, 68, 88, 84, 82}, {54, 66, 72, 62, 70, 66,
> 70,
>     56}, {60, 60, 60, 62, 74, 80, 70}, {54, 62, 64, 72, 76, 74}, {66,
> 74, 70,
>     80, 54, 54, 64}, {72, 66, 60, 52, 52, 66, 66, 58, 60, 66}}
> 
> What I'd really like is the average all the 1st values, 2nd values,
> etc, but I'm having trouble figuring out how to deal with the fact
> that the lists are not all the same length.   Is there a way to drop
> the sublists as they run out of points to add to the average, i.e. if
> I want the average of all the nth values, but Length[shortSublist] <
> n, can I somehow drop shortSublist and then calculate the average from
> the other sublists?
> 
> Also, the Mean[] function requires more than one data point, but I'd
> still like to extract out the values for which there is only one data
> point.  Is there a way to do this?
> 
> Thanks!
> dan
> 



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