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QuanTAlib/lib/errors/mdape/mdape.pine
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Miha Kralj 5ed4b6c0fc pine files
2026-01-31 14:05:53 -08:00

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// The MIT License (MIT)
// © mihakralj
//@version=6
indicator("Median Absolute Percentage Error", "MdAPE", overlay=false, format=format.percent)
//@function Calculates Median Absolute Percentage Error
//@doc Median of absolute percentage errors, robust to outliers.
//@doc Scale-independent (expressed as percentage), handles zero actual with epsilon.
//@param actual Series of actual values
//@param predicted Series of predicted/forecast values
//@param length Rolling window for median calculation
//@returns MdAPE value as percentage
mdape(series float actual, series float predicted, simple int length) =>
float epsilon = 1e-10
// Compute absolute percentage error for current bar
float absActual = math.abs(nz(actual, 1.0))
float absError = math.abs(nz(actual, 0.0) - nz(predicted, 0.0))
float pctError = absActual > epsilon ? (absError / absActual) * 100.0 : 0.0
// Use ta.median for rolling median of percentage errors
float result = ta.median(pctError, length)
result
// ---------- Main loop ----------
// Inputs
i_length = input.int(14, "Length", minval=1)
i_actual = input.source(close, "Actual")
i_predicted = input.source(open, "Predicted")
// Calculation
mdape_value = mdape(i_actual, i_predicted, i_length)
// Plot
plot(mdape_value, "MdAPE", color=color.yellow, linewidth=2)
hline(0, "Zero", color=color.gray, linestyle=hline.style_dotted)