List.RemoveAt

June 15th, 2012, 01:21 PM

Hi all!

Anyone know how to use List.RemoveAt(index)?

I'm using:

Code

list.RemoveAt(Count-1);

but putting the indicator in the chart the log says...

Code

Error on calling 'OnBarUpdate' method for indicator 'SercavaEnvelope4' on bar 86: You are accessing an index with a value that is invalid since its out of range. I.E. accessing a series [barsAgo] with a value of 5 when there are only 4 bars on the chart.

I'm confused: If you have a list, you always have list[Count-1]

Commenting that line gives no error. Perhaps is a method too new? (is new for 2.0 .NET Framework)

Thanks in advance,

Sergio

June 15th, 2012, 03:31 PM

@SerCava:

It is difficult to find an error, if you just post one line. What is "list"? How many elements has "list"?

NinjaTrader uses 2 variables for the BarsArray[] object.

CurrentBar: The first bar has the index CurrentBar = 0. The last bar in the data base typically has the value CurrentBar = Count -1, if the indicator is set to CalculateOnBarClose = true, the indicator value for the last bar is not plotted, meaning that the last indicator value shown corresponds to CurrentBar = Count -2.

When OnBarUpdate() is executed it starts with CurrentBar = 0, and then makes one iteration for each historical bar. On real-time bars it will make one iteration, if the indicator is set to CalculateOnBarClose = true, otherwise it will make one iteration with every incoming tick.

Count - 1 usually holds the integer equal to the total number of bars of the BarsArray loaded, while CurrentBar steps up with each iteration until it reaches the value Count-2 (CalculateOnBarClose = true) or Count-1 (CalculateOnBarClose = false).

June 15th, 2012, 04:11 PM

SerCava

I'm confused: If you have a list, you always have list[Count-1]

Commenting that line gives no error. Perhaps is a method too new? (is new for 2.0 .NET Framework)

Thanks in advance,

Sergio

@SerCava,

If I would guess, you need to check to see if "Count==0", this could create a negative index (which doesn't exist yet).

June 15th, 2012, 04:37 PM

As FatTails says, it's hard to tell from one line. But perhaps you mean to have:

List.RemoveAt(List.Count-1)

In NT, "Count", by itself, refers to the total # of bars.

June 16th, 2012, 05:24 AM

futuretrader

As FatTails says, it's hard to tell from one line. But perhaps you mean to have:

List.RemoveAt(List.Count-1)

In NT, "Count", by itself, refers to the total # of bars.

That was! Thanks. Sometimes you don't find the problem.... and I was using List.Count in other parts of the code, except in that line.

Thanks for all replies,

Sergio

List.RemoveAt

Discussion in NinjaTrader

List.RemoveAt