Passing array's element values to lowest or highest functions in pine script - arrays

Question

I am trying to pass dynamic values to lowest and highest built-in functions in pine script from arrays. Below is the code
int[] pArray = array.new_int(0)
pArray is populated with int elements. Here is the code below that works.
fromInd = array.min(pArray)
lowest = ta.lowest(MACDHist,array.get(pArray,0))
Debug = label.new(bar_index+1, close, 'pArray: ' + str.tostring(pArray) + str.tostring(fromInd))
The output of above code on the chart is
pArray: [2, 15, 40]2
2 is the 0th index value of pArray that is printed outside of the array in the end. However when I change the label to output 'lowest' value (shown below) nothing prints to chart but everything compiles well with no errors or warnings.
Debug = label.new(bar_index+1, close, 'pArray: ' + str.tostring(pArray) + str.tostring(lowest))
The output of 'array.get(id, index)' is series int because pArray is initialized to int. I also typecasted the 'array.get(id, index)' argument by enclosing it with 'int()' but nothing is working for the last line code except when hard coded.
'ta.lowest(source, length)' accepts series int arguments for length and it can also accept dynamic lengths as shown by tradingview https://www.tradingview.com/blog/en/pine-functions-support-dynamic-length-arguments-20554/
What am I doing wrong here? Thanks in advance.
I tried a variation of a solution posted by first user below with code
//#version=5
indicator("Dynamic INT array length", overlay = false, max_bars_back = 5000)
[a, b, hist] = ta.macd(close, 26, 12, 9)
int[] lengths = array.new_int()
int[] nlengths = array.new_int()
for i = 0 to 10
if hist[i] > 0
array.unshift(lengths, i)
else
array.unshift(nlengths,i)
lowest = ta.lowest(hist, array.get(lengths,0))
plot(lowest)
plot(hist, color = color.red)
debug = label.new(x = bar_index, y = 0, style = label.style_label_left, text = str.tostring(lowest) + " " + str.tostring(lengths) + " " + str.tostring(array.get(lengths,0)))
label.delete(debug[1])
and Im getting an error when using 'ta.lowest(hist, array.min(lengths))' where it says
Invalid value of the 'length' argument (0.0) in the "lowest" function. It must be > 0.
I tried all variations of the condition hist[i] > 0 within the for loop but nothing is printing and it has the same error. Let me know if there is an easy fix for this. Thanks.

Answer 1

It should be working, at a guess, normally I'd say there must be something going on with how the array is populated, but it doesn't seem to be the case here given the array output. It's unlikely, but possible you've found a bug, or an even possibly an exception that isn't being picked up by the compiler.
//#version=5
indicator("Dynamic INT array length", overlay = false, max_bars_back = 5000)
int[] lengths = array.new_int()
for i = 0 to 10
array.unshift(lengths, int(math.random(30, 50)))
[a, b, hist] = ta.macd(close, 26, 12, 9)
lowest = ta.lowest(hist, array.min(lengths))
plot(lowest)
plot(hist, color = color.red)
debug = label.new(x = bar_index, y = 0, style = label.style_label_left, text = str.tostring(lowest) + " " + str.tostring(lengths) + " " + str.tostring(array.min(lengths)))
label.delete(debug[1])
Follow up answer :
There's actually two things you need to take care of. If you consider when hist has been < 0 for a while (ie at least 10 bars). The first time hist crosses the zero line, your lengths array will only have one value : zero, and it can't be used in ta.lowest(). The second issue you will have is, if hist has been under zero the entire 10 bar window, the lengths array will be empty and array.get(lengths, 0) will give you the out of bounds indexing error.
You'll have to decide how to handle these specific circumstances, but the following of how you could account for it. For example using a length of 5 when the array has only one value of 0 and populating the arrays with na values to avoid the empty array problem.
//#version=5
indicator("Dynamic INT array length", overlay = false, max_bars_back = 5000)
[a, b, hist] = ta.macd(close, 26, 12, 9)
int[] lengths = array.new_int()
int[] nlengths = array.new_int()
for i = 0 to 10
if hist[i] > 0
array.unshift(lengths, i)
array.unshift(nlengths, na)
else
array.unshift(nlengths,i)
array.unshift(lengths, na)
int len = na
if array.get(lengths, 0) > 0
len := array.get(lengths, 0)
else
len := 5
lowest = ta.lowest(hist, len)
plot(lowest)
plot(hist, color = color.red)
debug = label.new(x = bar_index, y = 0, style = label.style_label_left, text = str.tostring(lowest) + " " + str.tostring(lengths) + " " + str.tostring(array.get(lengths,0)))
label.delete(debug[1])