From 283e9de30a716a5577a3205e87dbfeb24b6e47ba Mon Sep 17 00:00:00 2001
From: Brandon Clayton <bclayton@usgs.gov>
Date: Fri, 27 Sep 2024 10:26:44 -0600
Subject: [PATCH] fix interpolate to handle any array
---
libs/nshmp-lib/calc/maths.util.ts | 28 ++++++++++++++++++++--------
1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/libs/nshmp-lib/calc/maths.util.ts b/libs/nshmp-lib/calc/maths.util.ts
index bd67e9c..1f5aa0b 100644
--- a/libs/nshmp-lib/calc/maths.util.ts
+++ b/libs/nshmp-lib/calc/maths.util.ts
@@ -36,14 +36,12 @@ const interpolate = (xySequence: XySequence, value: number): number => {
const xValues = xySequence.xs;
const yValues = xySequence.ys;
- const indexBelow = yValues.findIndex(y => {
- return y < value;
- });
-
- const x0 = xValues[indexBelow - 1];
- const x1 = xValues[indexBelow];
- const y0 = yValues[indexBelow - 1];
- const y1 = yValues[indexBelow];
+ const index = closestIndex(yValues, value);
+
+ const x0 = xValues[index - 1];
+ const x1 = xValues[index];
+ const y0 = yValues[index - 1];
+ const y1 = yValues[index];
const x = interpolateValue(x0, x1, y0, y1, value);
return isNaN(x) ? x : round(x, 6);
};
@@ -90,6 +88,20 @@ const calculateResponseSpectrum = (
return interpolate(xySequence, 1 / returnPeriod);
};
+/**
+ * Return index of closest value.
+ *
+ * @param values Array of values
+ * @param value Value to find
+ */
+const closestIndex = (values: number[], value: number): number => {
+ const closestValue = values.reduce((prev, curr) =>
+ Math.abs(curr - value) < Math.abs(prev - value) ? curr : prev
+ );
+
+ return values.findIndex(value => value === closestValue);
+};
+
/**
* Interpolate.
*
--
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