Vector2D with Int, it does not implement Vector, maybe with generics later

Author: yitsushi

math/vector2d.go

@@ -61,3 +61,9 @@ func (v Vector2D) Neighbours() []Vector {
 func (v Vector2D) Values() []float64 {
 	return []float64{v.X, v.Y}
 }
+
+// Vector2DInt is a 2D vector.
+type Vector2DInt struct {
+	X int
+	Y int
+}

math/vector2dint.go

@@ -0,0 +1,63 @@
+package math
+
+import "math"
+
+// Rotate the vector.
+func (v *Vector2DInt) Rotate(angle float64) {
+	angle *= rad
+
+	cos, sin := math.Round(math.Cos(angle)), math.Round(math.Sin(angle))
+
+	x := (float64(v.X) * cos) - (float64(v.Y) * sin)
+	y := (float64(v.X) * sin) + (float64(v.Y) * cos)
+
+	v.X, v.Y = int(x), int(y)
+}
+
+// Hash for cache.
+func (v Vector2DInt) Hash() interface{} {
+	return v
+}
+
+// Manhattan distance.
+func (v Vector2DInt) Manhattan() int {
+	return int(math.Abs(float64(v.X)) + math.Abs(float64(v.Y)))
+}
+
+// Neighbours if it's a coordinate.
+func (v Vector2DInt) Neighbours() []Vector2DInt {
+	vectors := []Vector2DInt{}
+	checkRange := []int{-1, 0, 1}
+
+	//nolint: varnamelen // These are common names for coordinates.
+	for _, x := range checkRange {
+		for _, y := range checkRange {
+			if x == 0 && y == 0 {
+				continue
+			}
+
+			vectors = append(
+				vectors,
+				Vector2DInt{
+					X: v.X + x,
+					Y: v.Y + y,
+				},
+			)
+		}
+	}
+
+	return vectors
+}
+
+// Values for the vector as plain int slice.
+func (v Vector2DInt) Values() []int {
+	return []int{v.X, v.Y}
+}
+
+// Add two vectors together.
+func (v Vector2DInt) Add(v2 Vector2DInt) Vector2DInt {
+	return Vector2DInt{
+		X: v.X + v2.X,
+		Y: v.Y + v2.Y,
+	}
+}

math/vector2dint_test.go

@@ -0,0 +1,87 @@
+package math_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/yitsushi/go-aoc/math"
+)
+
+func TestVector2DInt_Rotate(t *testing.T) {
+	tests := []struct {
+		name     string
+		initial  math.Vector2DInt
+		degree   float64
+		expected math.Vector2DInt
+	}{
+		{
+			name:     "Rotate 90",
+			initial:  math.Vector2DInt{X: 1, Y: 0},
+			degree:   90,
+			expected: math.Vector2DInt{X: 0, Y: 1},
+		},
+		{
+			name:     "Rotate -90",
+			initial:  math.Vector2DInt{X: 1, Y: 0},
+			degree:   -90,
+			expected: math.Vector2DInt{X: 0, Y: -1},
+		},
+		{
+			name:     "Rotate 180",
+			initial:  math.Vector2DInt{X: 1, Y: 0},
+			degree:   180,
+			expected: math.Vector2DInt{X: -1, Y: 0},
+		},
+		{
+			name:     "Rotate -180",
+			initial:  math.Vector2DInt{X: 1, Y: 0},
+			degree:   -180,
+			expected: math.Vector2DInt{X: -1, Y: 0},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			v := &math.Vector2DInt{
+				X: tt.initial.X,
+				Y: tt.initial.Y,
+			}
+
+			v.Rotate(tt.degree)
+
+			assert.Equal(t, tt.expected.X, v.X)
+			assert.Equal(t, tt.expected.Y, v.Y)
+		})
+	}
+}
+
+func TestVector2DInt_Manhattan(t *testing.T) {
+	v := math.Vector2DInt{15, 33}
+
+	assert.Equal(t, int(48), v.Manhattan())
+}
+
+func TestVector2DInt_Hash(t *testing.T) {
+	v := math.Vector2DInt{15, 33}
+
+	assert.Equal(t, math.Vector2DInt{X: 15, Y: 33}, v.Hash())
+}
+
+func TestVector2DInt_Neighbours(t *testing.T) {
+	v := math.Vector2DInt{15, 33}
+
+	neighbors := v.Neighbours()
+
+	assert.Len(t, neighbors, 8)
+}
+
+func TestVector2DInt_Values(t *testing.T) {
+	v := math.Vector2DInt{15, 33}
+
+	assert.Equal(t, []int{15, 33}, v.Values())
+}
+
+func TestVector2DInt_Add(t *testing.T) {
+	v := math.Vector2DInt{15, 33}
+
+	assert.Equal(t, math.Vector2DInt{26, 36}, v.Add(math.Vector2DInt{11, 3}))
+}