associative arrays / hashtables ?

Unity Engine
1

I need to sort scores of players and thought of using associative arrays for this. I have a bit of a problem to get the code for this working in unity.

http://forum.unity3d.com/viewtopic.php?t=5967&highlight=hashtable

If I use this concept I get the error “type object does not allow slicing” when doing something like: print(_array[0][“a”]);

I also tried hashtables:

var newHash = new Hashtable();
newHash.Add("player"+1, 6);
newHash.Add("player"+2, 5);
for(key in newHash){
	str = str + " - " + newHash[key];
}
print(str);

Adding values works fine but it prints " - System.Collection.DictionaryEntry -System.Collection.DictionaryEntry".

How do I sort a hashtable on the value? And then afterwards, how can I go through the hashtable and get the “players” out of the keys instead of getting “System.Collection.DictionaryEntry”?

Thanks,
Raoul

2

Try:

for(key in newHash.Keys)
{
  // do something with newHash[key]
}
3

Thanks Matthew, that works well!

Probably this can be done much easier but the the following works for the sorting part of the players depending on scores:

function SortHashtable (inpHash : Hashtable) {
	var iVal; var key; var arrayValues = new Array(); var valuesKeysHash = new Hashtable(); var returnArray = new Array();
	// create arrays of values and reverse keys and values in valuesKeysHash hashtable
	for (key in inpHash.Keys) {
		arrayValues[arrayValues.length] = inpHash[key];
		valuesKeysHash.Add(inpHash[key], key);
	}
	// sort the array with values
	arrayValues.Sort();
	// create new array holding the new order of keys and return it
	for (iVal in arrayValues)
		returnArray[returnArray.length] = valuesKeysHash[iVal];
	return returnArray; 
}
4

There’s also a .Values property available from the Hashtable class (no need to iterate through with the keys to get the values). I guess I should have read your question more carefully :wink:

5

Yeh, I found that too. But, as it creates another hashtable where the key becomes the value and the value the key, I still need the key so I thought this was the easiest way to go.

6

Hmm, the code I posted actually doesn´t work. Players can have the same score and this will raise a “duplicated key” error on the line:

valuesKeysHash.Add(inpHash[key], key);

7

Sorry for the cranial density here, but looking at your posts, I just see pieces of this and I can’t quite wrap my brain around the whole thing.

I am also trying to make use of Hash Tables.

is Hashtable(); actual Unity syntax, or is this creating a standard multidimensional array, and you are just calling it “Hashtable();”?

It looks like the latter because I don’t see it in the docs.

Thanks.

8

Hashtable is a valid Unity type. It’s true, there’s no part of the docs that lists all the types. Also, another (less obvious) way of declaring a new hashtable is

var myHashTable = {};

–Eric

9

This worked for me in JS:

function Start () {
		var newHash = new Hashtable();
		newHash.Add("player"+1, 6);
		newHash.Add("player"+2, 5);
		
		//don't forget to declare str or else you get an unknown identifier 
		//also make it a type String or else you get NullReference exception
		var str:String;
		
		for(key in newHash.Keys)
		{
			print(key+ " - " + newHash.Item[key]);
			print(newHash[key]);
			str = str + " - " + newHash[key]; 
		}
		print(str);
		print(newHash["player1"]);
		print(newHash.Count);
}
10

Incidentally, the reason for the original error is that iterating over a Hashtable like this:-

for(key in newHash){ 
   str = str + " - " + newHash[key]; 
}

…doesn’t put the key into the iteration variable. It actually uses a DictionaryEntry, a key-value pair. The key is accessed with a property:-

for(entry in newHash){ 
   str = str + " - " + newHash[entry.Key]; 
}