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

*To*: mathgroup at smc.vnet.net*Subject*: [mg109911] Intersection of sublists on date and making a 2D list from a 3D one*From*: Garapata <warsaw95826 at mypacks.net>*Date*: Sat, 22 May 2010 00:42:39 -0400 (EDT)

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.