First implementation

util/util.go

@@ -0,0 +1,12 @@
+package util
+
+// Linear mapping between two ranges of values
+func MapRange(x, xmin, xmax, ymin, ymax float64) int {
+	Xrange := xmax - xmin
+	Yrange := ymax - ymin
+	XYratio := Xrange / Yrange
+
+	y := (x-xmin)/XYratio + ymin
+
+	return int(y)
+}

util/util_test.go

@@ -0,0 +1,32 @@
+package util
+
+import "testing"
+
+func TestRangeMapping(t *testing.T) {
+	cases := []struct {
+		x, xmin, xmax, ymin, ymax float64
+		expected                  int
+	}{
+		// Test positive
+		{-100, -100, 100, 0, 1000, 0},
+		{0, -100, 100, 0, 1000, 500},
+		{100, -100, 100, 0, 1000, 1000},
+
+		// Test negative
+		{0, 0, 100, 0, 1000, 0},
+		{50, 0, 100, 0, 1000, 500},
+		{100, 0, 100, 0, 1000, 1000},
+
+		// Reverse
+		{0, 100, 0, 0, 1000, 1000},
+		{50, 100, 0, 0, 1000, 500},
+		{100, 100, 0, 0, 1000, 0},
+	}
+
+	for _, c := range cases {
+		val := MapRange(c.x, c.xmin, c.xmax, c.ymin, c.ymax)
+		if val != c.expected {
+			t.Errorf("MapRange(%.0f, %.0f, %.0f, %.0f, %.0f): %d, wants %d", c.x, c.xmin, c.xmax, c.ymin, c.ymax, val, c.expected)
+		}
+	}
+}