How to flatten the result of a nested split in a C# Lambda expression -

given string "a:b;c:d,e;f:g,h,i", split string flat list of 2 columns, 1 each key (to left of colon) , values (comma separated right of colon). result should this.

{     key: "a",     value: "b" }, {     key: "c",     value: "d" }, {     key: "c",     value: "e" }, {     key: "f",     value: "g" }, {     key: "f",     value: "h" }, {     key: "f",     value: "i" } 

the problem cannot flatten results of second split on comma across keys, return single list of keyvalue, rather list of list of keyvalue.

public class keyvalue {     public string key { get; set; }     public string value { get; set; } }  list<keyvalue> mc = "a:b;c:d,e;f:g,h,i"     .split(';')     .select(a =>     {         int colon = a.indexof(':');         string left = a.substring(0, colon);         string right = a.substring(colon + 1);         list<keyvalue> result = right.split(',').select(x => new keyvalue { key = left, value = x }).tolist();         return result;     })     .tolist(); 

thanks help.

you very close. method flatten sequence of sequences selectmany. add 1 end of existing code, since ends select, can in fact change selectmany , we're done:

list<keyvalue> mc = "a:b;c:d,e;f:g,h,i"     .split(';')     .selectmany(a =>     {         int colon = a.indexof(':');         string left = a.substring(0, colon);         string right = a.substring(colon + 1);         list<keyvalue> result = right.split(',')             .select(x => new keyvalue { key = left, value = x }).tolist();         return result;     })     .tolist();