Another isNAN() question

[sevensa]

Hi

I'm still quite new to ThinkScript and TOS in general and I am trying to understand isNAN() function. I see there are a couple of examples and questions, but I am still not quite sure about something.

I do understand that this is used to check if a parameter value is a number or not. Where my confusion come in is when I look at the example here:

https://tlc.thinkorswim.com/center/reference/thinkScript/Functions/Math---Trig/IsNaN

specifically, the first line line under Example1 from the link above:

def onExpansion = if IsNaN(close) then yes else no;
plot HighestClose = if onExpansion then HighestAll(close) else double.NaN;
plot LowestClose = if onExpansion then LowestAll(close) else double.NaN;

My question is, under what circumstances would IsNaN(close) not be number?

 

[halcyonguy]

Hi

I'm still quite new to ThinkScript and TOS in general and I am trying to understand isNAN() function. I see there are a couple of examples and questions, but I am still not quite sure about something.

I do understand that this is used to check if a parameter value is a number or not. Where my confusion come in is when I look at the example here:

https://tlc.thinkorswim.com/center/reference/thinkScript/Functions/Math---Trig/IsNaN

specifically, the first line line under Example1 from the link above:

def onExpansion = if IsNaN(close) then yes else no;
plot HighestClose = if onExpansion then HighestAll(close) else double.NaN;
plot LowestClose = if onExpansion then LowestAll(close) else double.NaN;

My question is, under what circumstances would IsNaN(close) not be number?

trying to read a price, when no price data exists, results in an error , nan

-------------------------------

get in the habit of trying to use addchartbubble() to display variable values, it will help you understand what the formulas are doing.
https://tlc.thinkorswim.com/center/reference/thinkScript/Functions/Look---Feel/AddChartBubble

when \n is used, it forces data after it to appear on a new text line, in the bubble.
i tend to use + "\n" + out of habit.
this line,
"close" + "\n" +
could have been written as,
"close\n" +

--------------------------

this test code displays the close price on all candles.

# test_nan
def p = 100;

addchartbubble(
1, p,
"close" + "\n" +
close
,color.yellow, yes);
#

plotting bubbles at a price level of $100.
each shows the close price of a candle.
during candles, a price is shown.
after the last candle, there is no price data, so no close price exists.
so trying to read close, when no price data exists, results in an error , nan

 

[sevensa]

Thank you, this is a very helpful tip. My confusion is that about why ThinkScript is trying to get the close for a bar that doesn't exist. If I use close, I would expect it to give me the close of the current bar. I didn't think that I need to check if ThinkScript might try to give me the close for a bar that doesn't exist beyond the current bar. But now I do and I guess the why doesn't matter, I just need to work with it.

 

[halcyonguy]

Thank you, this is a very helpful tip. My confusion is that about why ThinkScript is trying to get the close for a bar that doesn't exist. If I use close, I would expect it to give me the close of the current bar. I didn't think that I need to check if ThinkScript might try to give me the close for a bar that doesn't exist beyond the current bar. But now I do and I guess the why doesn't matter, I just need to work with it.

if you use addlabel(1, close);
it will show the close of the last bar

but each time a new bar appears on the chart, all the price data from all the bars are used to redraw all the lines and shapes on the chart.
so in formulas, close will be read from all bars


the area after the last bar is the expansion area.
see image above, bubbles were drawn in the expansion area, even though no bars exist.
there is still a placeholder so to speak , for bars.