Re: averaging sublists of different lengths
- To: mathgroup at smc.vnet.net
- Subject: [mg75506] Re: averaging sublists of different lengths
- From: dh <dh at metrohm.ch>
- Date: Thu, 3 May 2007 03:49:19 -0400 (EDT)
- References: <f19fql$4q7$1@smc.vnet.net>
Hi,
to get the mean of the i_th values, we first extract all rows with at
least i elements:
Cases[t1,x_/;Length[x]>=#],
and get the i-th element:Part[..,All,#]
We apply the "Mean" to the resulting list. This we do for all i.
Everything together, assuming the list is in "d":
Mean@Part[Cases[d,x_/;Length[x]>=#],All,#]&/@Range[Max@Length@d]
hope this helps, Daniel
dantimatter 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
>
>