Am Dienstag 03 November 2009 02:29:56 schrieb Magicloud Magiclouds:
Hi, Say I have something like this: [ Record { item = "A1", value = "0" } , Record { item = "B1", value = "13" } , Record { item = "A2", value = "2" } , Record { item = "B2", value = "10" } ] How to convert it into: [ XXInfo { name = "A", value1 = "0", value2 = "2" } , XXInfo { name = "B", value1 = "13", value2 = "10" } ] If XXInfo has a lot of members. And sometimes the original data might be not integrity.
Could you be a little more specific about what you want to achieve? As a first guess, you might use something like import Data.List import Data.Ord (comparing) import Data.Function (on) sortedRecords = sortBy (comparing item) records recordGroups = groupBy ((==) `on` (head . item)) sortedRecords -- now comes the tricky part, converting the groups to XXinfo -- if all groups are guaranteed to have the appropriate number of -- elements, you can use xxInfo [Record (c:_) v1, Record _ v2] = XXinfo [c] v1 v2 -- and then xxInfos = map xxInfo recordGroups -- if the groups may have different numbers of elements, it's going to be uglier