core: add Mahalanobis(), Inv(), Row(), amd Col() functions

Signed-off-by: deadprogram <[email protected]>

ROADMAP.md

@@ -15,19 +15,19 @@ Your pull requests will be greatly appreciated!
 - [ ] **core. Core functionality - WORK STARTED**
     - [X] **Basic structures**
     - [ ] **Operations on arrays - WORK STARTED**. The following functions still need implementation:
-        - [ ] [Mahalanobis](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga4493aee129179459cbfc6064f051aa7d)
+        - [X] [Mahalanobis](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga4493aee129179459cbfc6064f051aa7d)
         - [ ] [mulTransposed](https://docs.opencv.org/master/d2/de8/group__core__array.html#gadc4e49f8f7a155044e3be1b9e3b270ab)
         - [ ] [PCABackProject](https://docs.opencv.org/master/d2/de8/group__core__array.html#gab26049f30ee8e94f7d69d82c124faafc)
         - [X] [PCACompute](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga4e2073c7311f292a0648f04c37b73781)
         - [ ] [PCAProject](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga6b9fbc7b3a99ebfd441bbec0a6bc4f88)
         - [ ] [PSNR](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga07aaf34ae31d226b1b847d8bcff3698f)
-        - [ ] [randn](https://docs.opencv.org/master/d2/de8/group__core__array.html#gaeff1f61e972d133a04ce3a5f81cf6808)
-        - [ ] [randShuffle](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga6a789c8a5cb56c6dd62506179808f763)
-        - [ ] [randu](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga1ba1026dca0807b27057ba6a49d258c0)
-        - [ ] [setRNGSeed](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga757e657c037410d9e19e819569e7de0f)
+        - [X] [randn](https://docs.opencv.org/master/d2/de8/group__core__array.html#gaeff1f61e972d133a04ce3a5f81cf6808)
+        - [X] [randShuffle](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga6a789c8a5cb56c6dd62506179808f763)
+        - [X] [randu](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga1ba1026dca0807b27057ba6a49d258c0)
+        - [X] [setRNGSeed](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga757e657c037410d9e19e819569e7de0f)
         - [ ] [SVBackSubst](https://docs.opencv.org/master/d2/de8/group__core__array.html#gab4e620e6fc6c8a27bb2be3d50a840c0b)
         - [ ] [SVDecomp](https://docs.opencv.org/master/d2/de8/group__core__array.html#gab477b5b7b39b370bb03e75b19d2d5109)
-        - [ ] [theRNG](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga75843061d150ad6564b5447e38e57722)
+        - [X] [theRNG](https://docs.opencv.org/master/d2/de8/group__core__array.html#ga75843061d150ad6564b5447e38e57722)
 
     - [ ] XML/YAML Persistence
         - [ ] [FileStorage](https://docs.opencv.org/master/da/d56/classcv_1_1FileStorage.html)

core.cpp

@@ -95,6 +95,18 @@ bool Mat_IsContinuous(Mat m) {
     return m->isContinuous();
 }
 
+void Mat_Inv(Mat m) {
+    m->inv();
+}
+
+Mat Mat_Col(Mat m, int c) {
+    return new cv::Mat(m->col(c));
+}
+
+Mat Mat_Row(Mat m, int r) {
+    return new cv::Mat(m->row(r));
+}
+
 // Mat_Clone returns a clone of this Mat
 Mat Mat_Clone(Mat m) {
     return new cv::Mat(m->clone());
@@ -591,6 +603,10 @@ void Mat_Magnitude(Mat x, Mat y, Mat magnitude) {
     cv::magnitude(*x, *y, *magnitude);
 }
 
+double Mat_Mahalanobis(Mat v1, Mat v2, Mat icovar) {
+    return cv::Mahalanobis(*v1, *v2, *icovar);
+}
+
 void Mat_Max(Mat src1, Mat src2, Mat dst) {
     cv::max(*src1, *src2, *dst);
 }

core.go

@@ -343,6 +343,26 @@ func (m *Mat) IsContinuous() bool {
 	return bool(C.Mat_IsContinuous(m.p))
 }
 
+// Inv inverses a matrix.
+//
+// For further details, please see:
+// https://docs.opencv.org/4.x/d3/d63/classcv_1_1Mat.html#a039eb3c6740a850696a12519a4b8bfc6
+func (m *Mat) Inv() {
+	C.Mat_Inv(m.p)
+}
+
+// Col creates a matrix header for the specified matrix column.
+// The underlying data of the new matrix is shared with the original matrix.
+func (m *Mat) Col(col int) Mat {
+	return newMat(C.Mat_Col(m.p, C.int(col)))
+}
+
+// Row creates a matrix header for the specified matrix row.
+// The underlying data of the new matrix is shared with the original matrix.
+func (m *Mat) Row(row int) Mat {
+	return newMat(C.Mat_Row(m.p, C.int(row)))
+}
+
 // Clone returns a cloned full copy of the Mat.
 func (m *Mat) Clone() Mat {
 	return newMat(C.Mat_Clone(m.p))
@@ -1391,6 +1411,14 @@ func Magnitude(x, y Mat, magnitude *Mat) {
 	C.Mat_Magnitude(x.p, y.p, magnitude.p)
 }
 
+// Mahalanobis calculates the Mahalanobis distance between two vectors.
+//
+// For further details, please see:
+// https://docs.opencv.org/4.x/d2/de8/group__core__array.html#ga4493aee129179459cbfc6064f051aa7d
+func Mahalanobis(v1, v2, icovar Mat) float64 {
+	return float64(C.Mat_Mahalanobis(v1.p, v2.p, icovar.p))
+}
+
 // Max calculates per-element maximum of two arrays or an array and a scalar.
 //
 // For further details, please see:

core.h

@@ -283,6 +283,9 @@ Mat Mat_FromPtr(Mat m, int rows, int cols, int type, int prows, int pcols);
 void Mat_Close(Mat m);
 int Mat_Empty(Mat m);
 bool Mat_IsContinuous(Mat m);
+void Mat_Inv(Mat m);
+Mat Mat_Col(Mat m, int c);
+Mat Mat_Row(Mat m, int r);
 Mat Mat_Clone(Mat m);
 void Mat_CopyTo(Mat m, Mat dst);
 int Mat_Total(Mat m);
@@ -399,6 +402,7 @@ double KMeans(Mat data, int k, Mat bestLabels, TermCriteria criteria, int attemp
 double KMeansPoints(PointVector pts, int k, Mat bestLabels, TermCriteria criteria, int attempts, int flags, Mat centers);
 void Mat_Log(Mat src, Mat dst);
 void Mat_Magnitude(Mat x, Mat y, Mat magnitude);
+double Mat_Mahalanobis(Mat v1, Mat v2, Mat icovar);
 void Mat_Max(Mat src1, Mat src2, Mat dst);
 void Mat_MeanStdDev(Mat src, Mat dstMean, Mat dstStdDev);
 void Mat_Merge(struct Mats mats, Mat dst);

core_test.go

@@ -2373,6 +2373,31 @@ func TestMatMagnitude(t *testing.T) {
 	}
 }
 
+func TestMatMahalanobis(t *testing.T) {
+	src := NewMatWithSize(10, 10, MatTypeCV32F)
+	defer src.Close()
+
+	RandU(&src, Scalar{Val1: -128}, Scalar{Val1: 128})
+
+	icovar := NewMatWithSize(10, 10, MatTypeCV32F)
+	defer icovar.Close()
+	mean := NewMatWithSize(1, 10, MatTypeCV32F)
+	defer mean.Close()
+
+	CalcCovarMatrix(src, &icovar, &mean, CovarRows|CovarNormal, MatTypeCV32F)
+	icovar.Inv()
+
+	line1 := src.Row(0)
+	defer line1.Close()
+	line2 := src.Row(1)
+	defer line2.Close()
+
+	result := Mahalanobis(line1, line2, icovar)
+	if result == 0 {
+		t.Error("Mahalanobis result should not be empty.")
+	}
+}
+
 func TestMatMax(t *testing.T) {
 	src1 := NewMatWithSize(4, 4, MatTypeCV32F)
 	defer src1.Close()