Created
March 6, 2014 09:52
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| ///<summary> | |
| /// Returns a dictionary of lists keyed by row index. | |
| /// Each list in the dictionary corresponds to a row of values. | |
| /// "kvp" stands for "key-value pair". | |
| ///</summary> | |
| public class ListHelper | |
| { | |
| public static Dictionary<int, List<T>> ToVertical<T>(IEnumerable<T> list, int maxColumns) { | |
| if(list == null) { | |
| throw new ArgumentNullException("list"); | |
| } | |
| if(list.Count() < 1) { | |
| throw new ArgumentException("`list` must contain one or more values."); | |
| } | |
| if(maxColumns < 1) { | |
| throw new ArgumentException("`maxColumns` should be one or greater."); | |
| } | |
| var verticalDictionary = new Dictionary<int, List<T>>(); | |
| var rows = (int)Math.Ceiling((double)(list.Count())/maxColumns); //Calculate the no. of rows. | |
| //Map the supplied list into a list of key-value-pairs. | |
| var kvps = list.Select((c, index) => { | |
| return new { Key = index%rows, Value = c }; | |
| }); | |
| //Enumerate the key-value-pairs from the previous step and place their values in the verticalDictionary. | |
| foreach(var kvp in kvps) { | |
| if(verticalDictionary.Any(k => k.Key == kvp.Key)) { | |
| verticalDictionary[kvp.Key].Add(kvp.Value); | |
| } else { | |
| verticalDictionary.Add(kvp.Key, new List<T> { kvp.Value }); | |
| } | |
| } | |
| return verticalDictionary; | |
| } | |
| } | |
| //Example usage... | |
| var countries = new string [] { "Angola", "Burundi", "Chile", "Denmark", "Estonia", "France", "Germany", "Holland", "India", "Jamaica", "Kiribati", "Laos", "Moldova" }; | |
| var maxColumns = 4; | |
| var verticalValues = ListHelper.ToVertical(countries, maxColumns); | |
| var maxKey = verticalValues.Max(kvp => kvp.Key); | |
| for(int i = 0; i <=maxKey; i++) { | |
| Console.Write(String.Join(" | ", verticalValues[i]) + "\n"); | |
| } |
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