feat(helper): implement IsRising utility

helper/is_rising.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2021-2026 Onur Cinar.
+// The source code is provided under GNU AGPLv3 License.
+// https://github.com/cinar/indicator
+
+package helper
+
+// IsRising returns 1 if the current value is strictly greater than the value
+// n periods ago, and 0 otherwise.
+//
+// Example:
+//
+//	input := []int{1, 2, 5, 5, 8, 2, 1, 1, 3, 4}
+//	output := helper.IsRising(helper.SliceToChan(input), 2)
+//	fmt.Println(helper.ChanToSlice(output)) // [1, 1, 1, 0, 0, 0, 1, 1]
+func IsRising[T Number](c <-chan T, period int) <-chan T {
+	cs := Duplicate(c, 2)
+	cs[0] = Buffered(cs[0], period)
+	cs[1] = Skip(cs[1], period)
+
+	return Operate(cs[1], cs[0], func(current, previous T) T {
+		if current > previous {
+			return 1
+		}
+
+		return 0
+	})
+}

helper/is_rising_test.go

@@ -0,0 +1,71 @@
+// Copyright (c) 2021-2026 Onur Cinar.
+// The source code is provided under GNU AGPLv3 License.
+// https://github.com/cinar/indicator
+
+package helper_test
+
+import (
+	"testing"
+
+	"github.com/cinar/indicator/v2/helper"
+)
+
+func TestIsRising(t *testing.T) {
+	input := helper.SliceToChan([]int{1, 2, 5, 5, 8, 2, 1, 1, 3, 4})
+	expected := helper.SliceToChan([]int{1, 1, 1, 0, 0, 0, 1, 1})
+
+	actual := helper.IsRising(input, 2)
+
+	err := helper.CheckEquals(actual, expected)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestIsRisingDefaultPeriod(t *testing.T) {
+	input := helper.SliceToChan([]int{1, 3, 2, 5, 4})
+	expected := helper.SliceToChan([]int{1, 0, 1, 0})
+
+	actual := helper.IsRising(input, 1)
+
+	err := helper.CheckEquals(actual, expected)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestIsRisingAllRising(t *testing.T) {
+	input := helper.SliceToChan([]int{1, 2, 3, 4, 5})
+	expected := helper.SliceToChan([]int{1, 1, 1, 1})
+
+	actual := helper.IsRising(input, 1)
+
+	err := helper.CheckEquals(actual, expected)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestIsRisingNoneRising(t *testing.T) {
+	input := helper.SliceToChan([]int{5, 4, 3, 2, 1})
+	expected := helper.SliceToChan([]int{0, 0, 0, 0})
+
+	actual := helper.IsRising(input, 1)
+
+	err := helper.CheckEquals(actual, expected)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestIsRisingEqual(t *testing.T) {
+	input := helper.SliceToChan([]int{3, 3, 3, 3})
+	expected := helper.SliceToChan([]int{0, 0, 0})
+
+	actual := helper.IsRising(input, 1)
+
+	err := helper.CheckEquals(actual, expected)
+	if err != nil {
+		t.Fatal(err)
+	}
+}