/// <summary>
/// returns a list of lists emulating a left join between two hashmaps
/// </summary>
/// <param name="datHM1">the left table represented by a hashmap</param>
/// <param name="datHM2">the right table represented by the hash map</param>
/// <returns>the resulting table as a list of string lists after performing a left join</returns>
public static List <List <string> > LeftJoin(HashMap datHM1, HashMap datHM2)
{
// making an assumption that we're allowed to know the keys of a hashmap
List <string> hMap1Keys = new List <string> {
"fond", "wrath", "diligent", "outfit", "guide"
};
List <string> hMap2Keys = new List <string> {
"fond", "wrath", "diligent", "guide", "flow"
};
List <string> hMap2Values = new List <string>();
foreach (var key in hMap2Keys)
{
hMap2Values.AddRange(datHM2.Find(key));
}
for (int i = 0; i < hMap2Keys.Count; i++)
{
datHM1.AddJoin(hMap2Keys[i], hMap2Values[i]);
}
foreach (var key in hMap1Keys)
{
// emulating the .contains method because
// Collin got jealous that I was using it
bool isHMap1Key = false;
foreach (var hMap2Key in hMap2Keys)
{
if (hMap2Key == key)
{
isHMap1Key = true;
break;
}
}
if (isHMap1Key == false)
{
datHM1.AddJoin(key, null);
}
}
List <List <string> > returnLists = new List <List <string> >();
foreach (var key in hMap1Keys)
{
List <string> tempList = new List <string> {
key
};
tempList.AddRange(datHM1.Find(key));
returnLists.Add(tempList);
}
return(returnLists);
}
