/// <summary>
/// Checks if hashtable2 has the hashtable1 key
/// if it exists, add the value of that key from HashTable2 and Hashtabel1 to Hashtable3
/// if it doesn't exist, add only the key value pair from Hashtable1 to Hashtable3 along
/// with the string "null" to indicate that Hashtable2 did not have that key
/// </summary>
/// <param name="ht1">HashTable1</param>
/// <param name="ht2">HashTable2</param>
/// <returns>HashTable3 with a left join</returns>
public HashTable LeftJoinHashTable(HashTable ht1, HashTable ht2)
{
//instantiate a new hashtable to store the left join table
HashTable ht3 = new HashTable();
for (int i = 0; i < ht1.HashArray.Length; i++)
{
if (ht1.HashArray[i] != null)
{
Console.WriteLine($"checking {ht1.HashArray[i].Key}");
if (ht2.Contains(ht1.HashArray[i].Key))
{
//ht2 has ht1 key, so add it to ht3
ht3.Add(ht1.HashArray[i].Key, ht1.HashArray[i].Value);
//add ht2's value to the same key
ht3.Add(ht1.HashArray[i].Key, ht2.HashArray[i].Value);
Console.WriteLine($"found a match for {ht1.HashArray[i].Key}");
}
else if (!ht2.Contains(ht1.HashArray[i].Key))
{
Console.WriteLine($"didn't find a match for {ht1.HashArray[i].Key}");
//ht2 does not have ht1 key, so add ht1's current key value pair
ht3.Add(ht1.HashArray[i].Key, ht1.HashArray[i].Value);
//also add ht1's key and a "null" to represent that ht2 did not have ht1's key
ht3.Add(ht1.HashArray[i].Key, "null");
}
}
}
return(ht3);
}
static public string[][] LeftJoin(HashTable synonyms, HashTable antonyms)
{
List <string[]> result = new List <string[]>();
foreach (var b in synonyms.Buckets)
{
if (b != null)
{
LinkedListNode <string[]> current = b.First;
while (current != null)
{
result.Add(new string[] { current.Value[0], current.Value[1], "NULL" });
current = current.Next;
}
}
}
foreach (var k in result)
{
if (antonyms.Contains(k[0]))
{
k[2] = antonyms.Get(k[0]);
}
}
return(result.ToArray());
}
public static List <string[]> LeftJoin(HashTable hashTableA, HashTable hashTableB)
{
List <string[]> results = new List <string[]>();
foreach (var bucket in hashTableA.Contents)
{
if (bucket != null)
{
foreach (var kvPair in bucket)
{
string[] result = new string[] { kvPair.Key, kvPair.Value, null };
results.Add(result);
if (hashTableB.Contains(kvPair.Key))
{
result[2] = hashTableB.Get(kvPair.Key);
}
}
}
}
return(results);
}
/// <summary>
/// Left joins two HashTable<string> objects.
/// </summary>
/// <param name="leftTable">
/// HashTable<string>: the HashTable<string> to be used as the left table in the left join
/// </param>
/// <param name="rightTable">
/// HashTable<string>: the HashTable<string> to be used as the right table in the left join
/// </param>
/// <returns>
/// HashTable<string>: a HashTable<LeftJoinNode>, containing the keys and values from leftTable and rightTable, left joined together
/// </returns>
public static HashTable <LeftJoinNode> LeftJoinHashTables(HashTable <string> leftTable, HashTable <string> rightTable)
{
HashTable <LeftJoinNode> leftJoin = new HashTable <LeftJoinNode>();
for (int i = 0; i < leftTable.HashMap.Length; i++)
{
if (leftTable.HashMap[i] != null)
{
var currNode = leftTable.HashMap[i].First;
while (currNode != null)
{
LeftJoinNode newLeftJoinNode = new LeftJoinNode(currNode.Value.Value);
if (rightTable.Contains(currNode.Value.Key))
{
newLeftJoinNode.RightValue = rightTable.Get(currNode.Value.Key);
}
leftJoin.Add(currNode.Value.Key, newLeftJoinNode);
currNode = currNode.Next;
}
}
}
return(leftJoin);
}
