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MathGroup Archive 2007

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Re: ListDimension function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg72575] Re: [mg72595] ListDimension function
  • From: János <janos.lobb at yale.edu>
  • Date: Thu, 11 Jan 2007 02:16:18 -0500 (EST)
  • References: <200701100907.EAA13288@smc.vnet.net>

On Jan 10, 2007, at 4:07 AM, carlos at colorado.edu wrote:

> Hi - I need a short function ListDimension that
> given a list returns its "brace dimensionality" =
> max number of brace levels to reach deepest entry.
> Examples
>
>    List         ListDimension
>    a+b                   0
>    {1,2,x*y}             1
>    {1,2,{3,0,1}}         2
>    {{},{},{}}            2
>    {{},{{1,2}},a}        3
>
> Built-in functions dont seem to be of help.
> Dimensions is restricted to matrix or tensor type of lists.
> Depth (minus 1) doesnt help as it is entry type dependent:
>
>    Depth[{1,2,3}] -> 2
>    Depth[{1,2,3+a}] -> 3
>    Depth[{1,2,3+a+Sqrt[x+y]}] -> 5
>
> For the above three, ListDimension=1.

Here is a newbie approach.

If your list is lst, then:

In[2]:=
Max[Length /@ Position[lst,
     List]]
Out[2]=
3

will work.  For a+b it gives minus Infinity if you can live with that.

János


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