Using Dictionary in indicator

[CaptainAmericaXX]

Hello,
I'm starting on a new course for me: Dictionaries.
I'm getting an error that, "the given key was not present in the dictionary". I have verified through Print() that the valleysRising.Key does have value, but for some reason around the 25th bar I get the error. Here is my code.

 #region Variables
        B1StochDir2                stochDirection;
        B1HourGlass               hourGlass;
        B1PVStoch                  stochPV;

        protected                     Dictionary<int, ValleysRising> valleys;

        #endregion

        protected override void Initialize()
        {
            Overlay                  = true;
            BarsRequired        = 15;
        }
        protected override void OnStartUp()
        {
            stochDirection              = B1StochDir2(3, 5, 2);
            hourGlass                    = B1HourGlass(14, 14, 7, 15, 3);
            stochPV                       = B1PVStoch(3, 5, 2);        
        }

        protected override void OnBarUpdate()
        {
            if(CurrentBar < BarsRequired) return;

            var valleysRising     = new ValleysRising(){Key = 1};

            valleys    = new Dictionary<int, ValleysRising>();

            for (int x = 0; x <= 3; x++){
                if(stochPV.StochValley[x] != -1){
                    valleysRising.BarNumber      = CurrentBar;
                    valleysRising.Value                = stochPV.StochValley[x];
                    valleys.Add(valleysRising.Key, valleysRising);
                    break;
                }    
            }
            Print(CurrentBar);
            Print(valleysRising.Key);
            Print("");

            ValleysRising valleysCheck     =    valleys[1];    
        }

        #region Properties

        #endregion
    }
    public class ValleysRising
    {
        public int           Key                {get; set;}        
        public int           BarNumber    {get; set;}
        public double    Value             {get; set;}

        public ValleysRising(){

    }
  }

Would someone mind taking a look at this?

[NinjaTrader_ChelseaB]

Hello CaptainAmericaXX,

What line is line of code causing the error?

Is it the 'stochPV.StochValley[x]' that has the invalid key?

Is it valleys[1]?

Use prints on different lines in the script to see where the code is stopping with an error.
https://ninjatrader.com/support/foru...121#post791121


Also, below I am including a sample script that uses a dictionary.

http://ninjatrader.com/support/forum/showthread.php?p=509144#post509144

[koganam]

Hello,
I'm starting on a new course for me: Dictionaries.
I'm getting an error that, "the given key was not present in the dictionary". I have verified through Print() that the valleysRising.Key does have value, but for some reason around the 25th bar I get the error. Here is my code.

#region Variables
B1StochDir2 stochDirection;
B1HourGlass hourGlass;
B1PVStoch stochPV;

protected Dictionary<int, ValleysRising> valleys;

#endregion

protected override void Initialize()
{
Overlay = true;
BarsRequired = 15;
}
protected override void OnStartUp()
{
stochDirection = B1StochDir2(3, 5, 2);
hourGlass = B1HourGlass(14, 14, 7, 15, 3);
stochPV = B1PVStoch(3, 5, 2);
}

protected override void OnBarUpdate()
{
if(CurrentBar < BarsRequired) return;

[COLOR=#FF0000]var valleysRising = new ValleysRising(){Key = 1};

valleys = new Dictionary<int, ValleysRising>();[/COLOR]

for (int x = 0; x <= 3; x++){
if(stochPV.StochValley[x] != -1){
valleysRising.BarNumber = CurrentBar;
valleysRising.Value = stochPV.StochValley[x];
valleys.Add(valleysRising.Key, valleysRising);
break;
}
}
Print(CurrentBar);
Print(valleysRising.Key);
Print("");

ValleysRising valleysCheck = valleys[1];
}

#region Properties

#endregion
}
public class ValleysRising
{
public int Key {get; set;}
public int BarNumber {get; set;}
public double Value {get; set;}

public ValleysRising(){

}
}

Would someone mind taking a look at this?

The text that I have marked in red means that you are recreating those two object on every pass of OBU. Why?

It does mean though that if your for loop runs less than 2 times in a pass, there will be only one value in valleys. i.e., valleys[1] would not exist.

[CaptainAmericaXX]

Thank you both for your help.
Chelsea_B, as koganam discovered, the issue was in my for loop index. I'm currently trying to understand why this would cause an error. Do you happen to have a dictionary sample script for NT7? I'm still way old school.

koganam,

The text that I have marked in red means that you are recreating those two object on every pass of OBU. Why?

I chuckle whenever someone asks me why I did something some way. The answer always is, "I don't know. I thought it would work." I thought there would be an issue every time OBU updated, but I didn't know another way to do it. If you could show me the proper way to initialize the dictionary I would be grateful.

[koganam]

Thank you both for your help.
Chelsea_B, as koganam discovered, the issue was in my for loop index. I'm currently trying to understand why this would cause an error. Do you happen to have a dictionary sample script for NT7? I'm still way old school.

koganam,

I chuckle whenever someone asks me why I did something some way. The answer always is, "I don't know. I thought it would work." I thought there would be an issue every time OBU updated, but I didn't know another way to do it. If you could show me the proper way to initialize the dictionary I would be grateful.

1. Given what appears to be the logic, I would say just declare/initialize both of those as class variables, instead of local variables in OBU.
2. Check the count of any collection before you access the indexed value, and act as necessary, even if it means throwing an exception.

[bltdavid]

The first line marked in red should stay where it is.
This is because valleysRising is the object being added to the dictionary,
so each time you want to Add valleysRising to the valleys dictionary, it should
be a new ValleysRising object.

The second line marked in red should be moved to OnStartUp.
This is because valleys is the dictionary, and it only needs to instantiated
one time, so move it out of OnBarUpdate and into OnStartUp. It is already
a protected class variable, so that part is fine.

The class ValleysRising has a data member named Key, which is probably not
necessary -- since if your Key is just an integer which is always incrementing,
then a List is probably better than Dictionary. But, in your code, I see you are
not incrementing Key, but it stays the value of '1' for every valleysRising object
added to the Dictionary. Why not eliminate the 'Key' data member and just use
the 'BarNumber' data member as the dictionary key? After all, BarNumber is
unique for every bar, because you assign it the value of CurrentBar.

You have other problems, too. The valleysCheck variable is assigned the
reference from valleys[1], but that is not the correct way to access a dictionary.
And, for whatever you're trying to do, valleys[1] is the 2nd item and won't exist
if valleys only has 1 item in it. That is, valleys[0] is the first item, not valleys[1].

I think for your particular use case above, a Dictionary is probably poor choice,
as it unnecessarily complicates things. I'd recommend the use of a List instead.

But, if your desire is to learn, throw in a few reading assignments for your self,
there are many all across the internet. For example,

https://www.google.com/search?q=c%23...tionary+values
https://www.tutorialsteacher.com/csh...arp-dictionary

Hang in there!

[CaptainAmericaXX]

Thanks for all the help. I followed bltdavid's advice and changed the Dictionary for a List.
I was hoping that by using a Dictionary/List that I would be able to save all specified past values in memory. What I'm getting now is a new, updated value every time OBU is called which really is nothing better that creating a variable. My ignorance of Lists and how the OnBarUpdate() works is limiting my ability to obtain my desired result.
I'm trying to capture the values of what I call "valleys" in which an indicator comes to a visual bottom point. I wanted to then compare those past valleys against new valleys as they're created. What I'm trying to create is a collection that shows, for instance, bars 5, 10, 13, 20, with values of 22, 30, 50, 90 etc.
The logic for getting the "valley" is sound, but I can't save more than one value at a time. Can anyone give me an idea of how to do this?
Thanks

[koganam]

Thanks for all the help. I followed bltdavid's advice and changed the Dictionary for a List.
I was hoping that by using a Dictionary/List that I would be able to save all specified past values in memory. What I'm getting now is a new, updated value every time OBU is called which really is nothing better that creating a variable. My ignorance of Lists and how the OnBarUpdate() works is limiting my ability to obtain my desired result.
I'm trying to capture the values of what I call "valleys" in which an indicator comes to a visual bottom point. I wanted to then compare those past valleys against new valleys as they're created. What I'm trying to create is a collection that shows, for instance, bars 5, 10, 13, 20, with values of 22, 30, 50, 90 etc.
The logic for getting the "valley" is sound, but I can't save more than one value at a time. Can anyone give me an idea of how to do this?
Thanks

In that case, a better design is to use a struct (or a class, but a class is rather heavy weight for such a simple case) to hold your paired values. Then you can populate and put the structs in a List. That way you can query the list by index to find particular offset valleys (like the 3rd most recent valley etc.), and you can also iterate through the list by index to find either/both of the bar index and value of the corresponding valley (e.g., how many valleys ago was the one that occurred on bar 15?).