In September, some of our built-in Pine functions started supporting dynamic values as their length arguments. And now we’ve expanded this list even further. The following functions can now also be used with dynamically calculated lengths:
bb() bbw() cci() cmo() cog() correlation() dev() falling() mfi() percentile_linear_interpolation() percentile_nearest_rank() percentrank() rising() roc() stdev() stoch() variance() wpr()
Passing series as the length argument makes it easier to create adaptive Pine indicators that use calculations based on variable periods. For example, the following script uses the built-in stdev() function to calculate the Standard Deviation bands for the VWAP indicator. The length of the stdev() calculation increases by 1 with every bar until the VWAP period resets:
//@version=4 study(title="VWAP", shorttitle="VWAP", overlay=true) src = input(title = "Source", type = input.source, defval = hlc3) t = time("D") start = na(t) or t > t sumSrc = src * volume sumVol = volume sumSrc := start ? sumSrc : sumSrc + sumSrc sumVol := start ? sumVol : sumVol + sumVol vwapValue = sumSrc / sumVol var barsSinceStart = 0 if start barsSinceStart := 0 barsSinceStart := barsSinceStart + 1 stdevLen = bar_index == 0 ? 3000 : barsSinceStart // max_bars_back workaround vwapStdev = stdev(vwapValue, stdevLen) plot(vwapValue, title="VWAP", color=color.blue) upperBand = plot(vwapValue+vwapStdev, title="Upper Band", color=color.green) lowerBand = plot(vwapValue-vwapStdev, title="Lower Band", color=color.green) upperBand2 = plot(vwapValue+vwapStdev*2, title="Upper Band 2", color=color.yellow) lowerBand2 = plot(vwapValue-vwapStdev*2, title="Lower Band 2", color=color.yellow) fill(upperBand2, lowerBand2, color=color.yellow, transp=95)
Keep in mind that these functions require evaluation on every bar, so they should be used outside `for` loops or `if` blocks that are not executed on every bar. Additionally, passing a series as the length for a built-in function can sometimes cause the `Pine cannot determine the referencing length of a series` error. You can learn more about it and how to work around the error in our Help Center.
Read about all updates to Pine in our User Manual’s Release Notes.
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