http://snippets.dzone.com/posts Sat, 17 May 2008 22:04:27 GMT DZone Snippets: group-by code http://snippets.dzone.com/posts/show/1124 <code> <br /> group-by: func [ <br /> {Returns a block of blocks+sub-blocks with items partitioned by <br /> matching index elements in each sub-block.} <br /> block [any-block!] "A block of blocks" <br /> index [integer!] "Index of sub-block value to compare, for grouping." <br /> /local keys <br /> ][ <br /> result: copy [] <br /> foreach item block [ <br /> if not find/skip result item/:index 2 [ <br /> append result reduce [item/:index copy []] <br /> ] <br /> ] <br /> foreach item block [ <br /> append/only select result item/:index item <br /> ] <br /> result <br /> ] <br /> ;group-by [[a 1 2] [b 2 3] [a 2 4] [c 2 3] [b 1 5]] 1 <br /> ;group-by [[a 1 2] [b 2 3] [a 2 4] [c 2 3] [b 1 5] [c 2 4]] 2 <br /> ;group-by [[a 1 2] [b 2 3] [a 2 4] [c 2 3] [b 1 5] [c 2 4]] 3 <br /></code> Tue, 10 Jan 2006 06:17:23 GMT http://snippets.dzone.com/posts/show/1124 gregg.irwin (Gregg Irwin)