Re: Intersection of sublists on date and making a 2D list from a 3D

• To: mathgroup at smc.vnet.net
• Subject: [mg109932] Re: Intersection of sublists on date and making a 2D list from a 3D
• From: Ray Koopman <koopman at sfu.ca>
• Date: Sun, 23 May 2010 03:18:15 -0400 (EDT)
• References: <ht7nbh\$psj\$1@smc.vnet.net>

Further to my earlier post, the whole thing would then be

Function[i,Flatten@{i,Cases[#,{x_,y_,i}:>{x,y},{1},1]&/@list}] /@
Intersection@@(#[[All,3]]&/@list)

On May 21, 9:42 pm, Garapata <warsaw95... at mypacks.net> wrote:
> I have a list with the following dimensionality:
>
>    Dimensions[list]
>    Dimensions[list[[1]]]
>    Dimensions[list[[2]]]
>    Dimensions[list[[3]]]
>
>    {3}
>    {130, 3}
>    {126, 3}
>    {191, 3}
>
> I think of it as 3 groups, each with a different number of rows, but
> each of these rows has 3 columns.  Of the 3 columns, the third has
> dates in a DateList format.
>
> So, I can simulate the list with the following:
>
> a = Table[{RandomInteger[10], RandomInteger[10], DatePlus[{2010, 1,
> 1}, RandomInteger[{1, 150}]]}, {1}, {191}];
> list = Join[a[[All, 4 ;; 133, All]], a[[All, 1 ;; 126, All]], a];
>
> Ultimately I'd like to find all the rows that intersect on the same
> dates and put the whole thing into a 2 dimensional structure that
> would have the following columns:
>
> commonDates, group1Data1, group1Data2, group2Data1, group2Data2,
> group3Data1, group3Data2,
>
> I can use Intersect[] to find the common dates:
>
>    Intersection[list[[1, All,3]], list[[2, All, 3]], list[[3, All,
> 3]]];
>
> but this seems a bit cumbersome given I may have a greater or lesser
> number of groups.  Seems like I need to start this in a better way,
> but since Intersection[] doesn't take a list of lists I don't know
> where to take this.
>
> Probably easier if I had a more regular structure but I don't.
>
> Any help in pointing me in the right direction much appreciated.
>
> Thx to all.

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