Charts are laggy due to custom study

[letsfingo]

First of all, this is not a computer performance issue. I have increased my memory allocation to TOS. Memory, CPU and GPU all have plenty to spare.

For some reason charts are lagging by a few seconds when I have this study enabled. The study checks to see if the chart symbol matches and if it does then it plots some lines.

It's a very simplistic study that basically does something similar to this for a bunch of symbols:

if GetSymbol() == "NVDA" { plotline = 250.00;}
else if GetSymbol() == "AAPL" { plotline = 150.00;}

I would understand if the performance of the chart was affected upon the initial loading of the chart, but it is being affected continuously while I have the chart open. The plot lines of the study are static and therefore don't need to be redrawn after the initial loading of the chart. Is there a way to stop this study from continuously affecting the performance of the charts?

 

[Joshua]

How many symbols is a bunch of symbols? They are redrawn, once per bar, every tick, whether they need to be or not. They are just redrawn in the same place. Declaring once_per_bar might help. I am curios why you don't just draw them manually if they are static? Moving the drawing when necessary is no more complicated than changing the value in the script.

 

[letsfingo]

Unfortunately, declaring once per bar didn't help. I understand that the lines are redrawn every bar, however, I think that it is the IF statements that are slowing it down. It is having to run through all of the IF and ELSE IF statements for every bar. The IF statements only serve to match the plotlines to the correct symbol. If it were possible to only run through the if statements once and then ignore them for subsequent runs, then this could fix the issue. I don't mind the lines being redrawn but I would like to have the variables for the lines already saved and avoid rerunning the IF statements, is that possible?

 

[Joshua]

You might be able to do something like the following, and it might speed up the code. It should only check the symbols on the first bar, then it should just continue to draw the line based on the line's own value. Although, it depends on how the platform interprets code in general, which is not something that is explained or documented. I am interested to hear the results.

def x;
if !x[1] {
    x = if getsymbol() == "NVDA" then 250
    else if getsymbol() == "AAPL" then 150
    else -1;
} else {
    x =  x[1];
}
plot y = x;

 

[dj45]

According to a TOS rep I spoke with, custom scripts run slower than TOS built-in scripts, so for some lag I was experiencing, he suggested I replace custom scripts with built-in scripts where feasible (among other suggestions).

Not sure why, but there does seem to be some truth to this.

 

[halcyonguy]

You might be able to do something like the following, and it might speed up the code. It should only check the symbols on the first bar, then it should just continue to draw the line based on the line's own value. Although, it depends on how the platform interprets code in general, which is not something that is explained or documented. I am interested to hear the results.

def x;
if !x[1] {
    x = if getsymbol() == "NVDA" then 250
    else if getsymbol() == "AAPL" then 150
    else -1;
} else {
    x =  x[1];
}
plot y = x;

thanks for posting that code in post#4.
i've never seen a variable set to a value, before bar #1.

i made this test version, to see what the variables are doing, but , still confused, ... heh
it displays bubbles with values.
at bar #1, x[1] has the desired value, 150 ...

# firstbar_stuff_00

def bn = barnumber();
def x;
if !x[1] {
    x = if getsymbol() == "NVDA" then 250
    else if getsymbol() == "AAPL" then 150
    else -1;
} else {
#    x =  x[1];
    x = 22;
}
plot y = x;

addchartbubble( ( bn < 4 ), low, "bn " + bn + "\nX " + x + "\n!x " + !x + "\nX1 " + x[1] + "\n!x1 " + !x[1], color.cyan, no);
#

 

[letsfingo]

You might be able to do something like the following, and it might speed up the code. It should only check the symbols on the first bar, then it should just continue to draw the line based on the line's own value. Although, it depends on how the platform interprets code in general, which is not something that is explained or documented. I am interested to hear the results.

def x;
if !x[1] {
    x = if getsymbol() == "NVDA" then 250
    else if getsymbol() == "AAPL" then 150
    else -1;
} else {
    x =  x[1];
}
plot y = x;

Thank you! I will give it a try and let you know how it goes.

 

[Joshua]

thanks for posting that code in post#4.
i've never seen a variable set to a value, before bar #1.

i made this test version, to see what the variables are doing, but , still confused, ... heh

If you call an inline offset, like def X = X[30], it will expose data beyond the left edge of the chart, and even cause BarNumber() to run negative. Its just something that is hard to notice because you never actually see it with your own eye. However, if you were then to Fold X = 1 to BarNumber() it will throw an assertion because the first bar number, in this case, actually becomes -29.