I hate it when I am too clever for my own good...

OriginalGriff

A lot like mine:

public class MovingAverage
    {
    private List<int> samples = new List<int>();
    private int total = 0;

    public int SampleSize { get; private set; }
    public decimal Value
        {
        get 
            {
            return samples.Count == SampleSize? (decimal)total / SampleSize : decimal.MinValue;
            }
        }
    public MovingAverage(int sampleSize = -1)
        {
        SampleSize = sampleSize;
        }
    /// <summary>
    /// Add a new sample to the average
    /// </summary>
    /// <param name="value"></param>
    public void Add(int value)
        {
        if (SampleSize > 0)
            {
            while (samples.Count >= SampleSize)
                {
                int remove = samples\[0\]; 
                samples.RemoveAt(0);
                total -= remove;
                }
            }
        samples.Add(value);
        total += value;
        }
    }

Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952) Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)

Kornfeld Eliyahu Peter

OriginalGriff wrote:

I don't fancy doing that in SQL

Why? SQL is extremely good in arithmetic...

I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is. (V)

PIEBALDconsult

SQL is neither moving, nor average.

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Brisingr Aerowing

Sounds like article fodder to me.

Kornfeld Eliyahu Peter

SQL has top(n) and order by for moving and avg(column) for average...

I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is. (V)

PIEBALDconsult

Maybe I should have included the joke icon. But also, is TOP part of the SQL standard?

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Kornfeld Eliyahu Peter

TOP as is not part of the standard... There is, however implementations in every SQL I know of... And of course - just for the fun - it's different in each an every of them... DB2 - select * from table fetch first 10 rows only MSSQL - select top(10) * from table MySQL - select * from table limit 10

I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is. (V)

Mike Hankey

I like to call those little divrersions "Flights of fancy" or "Magic Mike moments" :)

My site: Everything Embedded Relax...We're all crazy it's not a competition!

Jorgen Andersson

How about oracle? Without using a subquery that is. :)

Wrong is evil and must be defeated. - Jeff Ello[^]

Kornfeld Eliyahu Peter

I don't know Oracle from my experience but a short Googleing shows that it has it's own syntax - as expected... Oracle - select * from table where rownum <= n

I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is. (V)

Jorgen Andersson

Can't do that. Rownum is assigned in the beginning before ORDER BY. The result would be n random rows. Think of it as being processed in this order: 1. The FROM/WHERE clause goes first. 2. ROWNUM is assigned and incremented to each output row from the FROM/WHERE clause. 3. SELECT is applied. 4. GROUP BY is applied. 5. HAVING is applied. 6. ORDER BY is applied.

Wrong is evil and must be defeated. - Jeff Ello[^]

Kornfeld Eliyahu Peter

As I told I do not know Oracle form my own experience - found that bit in Google...

I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is. (V)

Jorgen Andersson

It's just one of my pet peeves, that Oracle lacks a limit clause. It's easy enough to fix with a subquery, I just believe I shouldn't need to.

Wrong is evil and must be defeated. - Jeff Ello[^]

Andy Brummer

Since this borders on a programming answer, I'm not going to give you the answer directly, but look at they way the two parameter sum function is implemented.

Curvature of the Mind now with 3D

TnTinMn

Quitter. You could have done it with some creativity using Linq.Expressions.

BillWoodruff

I like it ... when you are too clever for your own good. Me learn stuff.

“But I don't want to go among mad people,” Alice remarked. “Oh, you can't help that,” said the Cat: “we're all mad here. I'm mad. You're mad.” “How do you know I'm mad?” said Alice. “You must be," said the Cat, or you wouldn't have come here.” Lewis Carroll

OriginalGriff

That's the day not wasted then! :laugh:

Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952) Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)

CBadger

I had a similar problem once. (But I was more stubborn keeping it Generic) :rolleyes: So what i ended up doing was keeping with the object types, using that to filter each value and tryparse into decimal List class so that I could sum up everything. I just had to prepare for the worse so I put in my catch that if any error would occur to throw out the value and just log what went wrong, so that way when I picked up more errors (Which I did not much), i could just improve the tryparse :doh:

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Fueled By Decaff

You could do it by using a class that does the adding. You would need to specify the class to do the adding and the type it uses in the moving averages class. Something like this:

public interface IArithmetic<T>
{
T Add(T augend, T addend);
}

public class GenericAdd<T, U> where T : IArithmetic<U>, new()
{
T adder = new T();

public U AddGenericTypes(U augend, U addend)
{
    return adder.Add(augend, addend);
}

}

And for each type you want to use this with you will need one of these.

public class AddInt : IArithmetic<int>
{
public AddInt()
{
}

#region IArithmetic<int> Members

public int Add(int augend, int addend)
{
    return augend + addend;
}

#endregion

}

These can then be used like this:

GenericAdd<AddInt, int> intAdder = new GenericAdd<AddInt, int>();
int result = intAdder.AddGenericTypes(1, 2);

Seems like a lot of work to me unless you know you are going to need it.

irneb

You could of course go the fully OO route and make your own "number" class. I.e. the way you'd have done it prior to generics. Then add some implied conversion overloads so you don't need to manually type-cast your int/double/decimal/etc. You could then even accommodate other more complicated data types (e.g. to generate moving averages on a candle-stick-chart with 3 values per item: open, avg, close). BTW, for the data sample I'd go with either a double linked list (LinkedList with max length) or a circular array, not an Array List as you've done in your sample code (that's implemented as a flat array so a remove from index 0 means it shifts all samples down by 1, if you reverse the order then each insert would shift all items up by 1). Seeing as mostly you'd calculate by iterating over each item in the "list" and you'd not want to move all the samples in the array each time you get a new one the linked list should suffice for this purpose. The circular array I'd only use if I know the size sample will not change after initially creating the object and if I need to reference specific items by index. You could use a Queue type for this, as well. I "think" it's implemented as a linked list anyway. Here's what I'm thinking:

public class MyNumber {
	private object \_value;
	public object Value {
		get { return \_value; }
		set {
			if ((value is int) || (value is double) || (value is decimal))
				\_value = value;
			else throw new InvalidCastException();
		}
	}
	
	public MyNumber(object val) {
		Value = val;
	}
	
	public static implicit operator MyNumber(int val) { return new MyNumber(val); }
	
	public static implicit operator int(MyNumber val) { return (int)val.\_value; }
	
	public static implicit operator MyNumber(double val) { return new MyNumber(val); }
	
	public static implicit operator double(MyNumber val) { return (double)val.\_value; }
	
	public static implicit operator MyNumber(decimal val) { return new MyNumber(val); }
	
	public static implicit operator decimal(MyNumber val) { return (decimal)val.\_value; }
}

public class MovingAverage {
	private LinkedList \_samples = new LinkedList();
	private decimal total = 0;
	public int SampleSize { get; private set; }
	public decimal Value {
		get {
			if (SampleSize < 0) return (\_samples.Count > 0) ? total / \_samples.Count : 0;
			return (\_samples.Count >= SampleSize) ? tota