Average list of list of parameter values

Question

I have a list of lists of fitted parameter values, e.g.

list={{a->1,b->10},{a->2,b->20},{a->3,b->30}}

(the actual parameter names can vary, as well as the size of the list)

What is the easiest way then to obtain the average parameter values, in this case avg={a->2,b->20} ?

score 4 · Accepted Answer · answered May 01 '15 at 09:29

4

Normal@Merge[Mean][list]
(* {a -> 2, b -> 20} *)

answered May 01 '15 at 09:29

kglr

Perfect - thanks a lot!! – Tom Wenseleers May 01 '15 at 09:31
1

This is nifty: is it efficient? What if the list is very very long? Does going through Association have a penalty? – chris May 01 '15 at 09:58
@Tom, my pleasure. Thank you for the accept. – kglr May 01 '15 at 13:20
@chris, good question. I am not sure about the relative efficiency. It would be a good idea to do timing comparisons after a few more alternatives come in. – kglr May 01 '15 at 13:27

score 1 · Answer 2 · answered May 01 '15 at 10:24

1

A method that works on older versions of Mathematica is this:

{a, b} -> Map[Mean, Transpose[{a, b} /. list]]

but admittedly it won't be as fast as Merge.

answered May 01 '15 at 10:24

C. E.

2 Answers2