Added mode.go & mode_test.go (TheAlgorithms#523)

math/mode.go

@@ -0,0 +1,49 @@
+// mode.go
+// author(s): [CalvinNJK] (https://github.com/CalvinNJK)
+// description: Finding Mode Value In an Array
+// see mode.go
+
+package math
+
+import (
+	"errors"
+
+	"github.com/TheAlgorithms/Go/constraints"
+)
+
+// ErrEmptySlice is the error returned by functions in math package when
+// an empty slice is provided to it as argument when the function expects
+// a non-empty slice.
+var ErrEmptySlice = errors.New("empty slice provided")
+
+func Mode[T constraints.Number](numbers []T) (T, error) {
+
+	countMap := make(map[T]int)
+
+	n := len(numbers)
+
+	if n == 0 {
+		return 0, ErrEmptySlice
+	}
+
+	for _, number := range numbers {
+		if _, check := countMap[number]; check {
+			countMap[number]++
+		} else {
+			countMap[number] = 1
+		}
+	}
+
+	var mode T
+	count := 0
+
+	for k, v := range countMap {
+		if v > count {
+			count = v
+			mode = k
+		}
+	}
+
+	return mode, nil
+
+}

math/mode_test.go

@@ -0,0 +1,94 @@
+// mode.go
+// author(s): [CalvinNJK] (https://github.com/CalvinNJK)
+// description: Test for Finding Mode Value In an Array
+
+package math_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/TheAlgorithms/Go/constraints"
+	"github.com/TheAlgorithms/Go/math"
+)
+
+type testCase[T constraints.Number] struct {
+	name    string
+	numbers []T
+	mode    T
+	err     error
+}
+
+func testModeFramework[T constraints.Number](t *testing.T, testCases []testCase[T]) {
+	for _, test := range testCases {
+		t.Run(test.name, func(t *testing.T) {
+			returnMode, err := math.Mode(test.numbers)
+			if returnMode != test.mode {
+				t.Errorf("\n Failed test %s,\n Numbers: %v,\n Correct Mode: %v,\n Returned Mode: %v\n",
+					test.name, test.numbers, test.mode, returnMode)
+			}
+			if !errors.Is(err, test.err) {
+				t.Errorf("\n Failed test %s,\n Numbers: %v,\n Correct Error: %v,\n Returned Error: %v\n",
+					test.name, test.numbers, test.err, err)
+			}
+		})
+	}
+}
+func TestMode(t *testing.T) {
+	// test cases for integer values
+	intTestCases := []testCase[int]{
+		{
+			name:    "An array of positive whole numbers",
+			numbers: []int{10, 52, 10, 92, 10, 75, 60, 10, 44, 29},
+			mode:    10,
+			err:     nil,
+		},
+		{
+			name:    "An array of negative whole numbers",
+			numbers: []int{-19, -12, -74, -19, -22, -56, -19, -19, -68, -93},
+			mode:    -19,
+			err:     nil,
+		},
+		{
+			name:    "An array of positive & negative whole numbers",
+			numbers: []int{18, -28, 33, -28, 2, 39, 48, -49, -87, 78, -28},
+			mode:    -28,
+			err:     nil,
+		},
+		{
+			name:    "If array has no value",
+			numbers: []int{},
+			mode:    0,
+			err:     math.ErrEmptySlice,
+		},
+	}
+	testModeFramework(t, intTestCases)
+	// test cases for float64 values
+	floatTestCases := []testCase[float64]{
+		{
+			name:    "An array of positive real numbers",
+			numbers: []float64{1.5, 2.88, 84.4, 77.2, 29.8, 46.2, 33.7, 88.4, 88.4},
+			mode:    88.4,
+			err:     nil,
+		},
+		{
+			name:    "An array of negative real numbers",
+			numbers: []float64{-98.1, -26.8, -54.45, -26.8, -1.5, -26.8, -33, -19.5, -26.8},
+			mode:    -26.8,
+			err:     nil,
+		},
+		{
+			name:    "An array of positive and negative real numbers",
+			numbers: []float64{-17, 28.9, -5.2, -19.5, 77.3, -5.2, 39.3, 28.5, -59.77, -5.2},
+			mode:    -5.2,
+			err:     nil,
+		},
+		{
+			name:    "If array has no value",
+			numbers: []float64{},
+			mode:    0,
+			err:     math.ErrEmptySlice,
+		},
+	}
+	testModeFramework(t, floatTestCases)
+}