pine files

lib/errors/maape/maape.pine

@@ -0,0 +1,38 @@
+// The MIT License (MIT)
+// © mihakralj
+//@version=6
+indicator("Mean Arctangent Absolute Percentage Error", "MAAPE", overlay=false, format=format.percent)
+
+//@function Calculates Mean Arctangent Absolute Percentage Error
+//@doc     Uses arctangent to bound error between 0 and π/2, robust to outliers.
+//@doc     Handles zero actual values gracefully (approaches π/2).
+//@param   actual Series of actual values
+//@param   predicted Series of predicted/forecast values
+//@param   length Rolling window for averaging
+//@returns MAAPE value (0 to ~1.5708)
+maape(series float actual, series float predicted, simple int length) =>
+    float epsilon = 1e-10
+
+    // Compute arctangent percentage error for current bar
+    float absActual = math.abs(nz(actual, 0.0))
+    float absError = math.abs(nz(actual, 0.0) - nz(predicted, 0.0))
+    float atanError = absActual > epsilon ? math.atan(absError / absActual) : math.pi / 2.0
+
+    // Rolling mean of arctangent errors
+    float result = ta.sma(atanError, 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
+maape_value = maape(i_actual, i_predicted, i_length)
+
+// Plot
+plot(maape_value, "MAAPE", color=color.yellow, linewidth=2)
+hline(0, "Zero", color=color.gray, linestyle=hline.style_dotted)
+hline(math.pi / 2.0, "Max (π/2)", color=color.red, linestyle=hline.style_dotted)