Improve comments for clarity in logistic regression, stats overview, PCA, correlation, descriptive statistics, and matrix tests

src/matrix/mat.rs

@@ -1028,9 +1028,7 @@ mod tests {
 
     #[test]
     fn test_from_rows_vec() {
-        // Representing:
-        // 1 2 3
-        // 4 5 6
+        // Matrix with rows [1, 2, 3] and [4, 5, 6]
         let rows_data = vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0];
         let matrix = Matrix::from_rows_vec(rows_data, 2, 3);
 
@@ -1042,19 +1040,14 @@ mod tests {
 
     // Helper function to create a basic Matrix for testing
     fn static_test_matrix() -> Matrix<i32> {
-        // Column-major data:
-        // 1 4 7
-        // 2 5 8
-        // 3 6 9
+        // Column-major data representing a 3x3 matrix of sequential integers
         let data = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
         Matrix::from_vec(data, 3, 3)
     }
 
     // Another helper for a different size
     fn static_test_matrix_2x4() -> Matrix<i32> {
-        // Column-major data:
-        // 1 3 5 7
-        // 2 4 6 8
+        // Column-major data representing a 2x4 matrix of sequential integers
         let data = vec![1, 2, 3, 4, 5, 6, 7, 8];
         Matrix::from_vec(data, 2, 4)
     }
@@ -1132,10 +1125,7 @@ mod tests {
 
     #[test]
     fn test_from_cols_basic() {
-        // Representing:
-        // 1 4 7
-        // 2 5 8
-        // 3 6 9
+        // Matrix with columns forming a 3x3 sequence
         let cols_data = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]];
         let matrix = Matrix::from_cols(cols_data);
 
@@ -1512,8 +1502,7 @@ mod tests {
 
         // Delete the first row
         matrix.delete_row(0);
-        // Should be:
-        // 3 6 9
+        // Resulting data should be [3, 6, 9]
         assert_eq!(matrix.rows(), 1);
         assert_eq!(matrix.cols(), 3);
         assert_eq!(matrix.data(), &[3, 6, 9]);

src/matrix/seriesops.rs

@@ -215,20 +215,13 @@ mod tests {
 
     // Helper function to create a FloatMatrix for SeriesOps testing
     fn create_float_test_matrix() -> FloatMatrix {
-        // 3x3 matrix (column-major) with some NaNs
-        // 1.0  4.0  7.0
-        // 2.0  NaN  8.0
-        // 3.0  6.0  NaN
+        // 3x3 column-major matrix containing a few NaN values
         let data = vec![1.0, 2.0, 3.0, 4.0, f64::NAN, 6.0, 7.0, 8.0, f64::NAN];
         FloatMatrix::from_vec(data, 3, 3)
     }
 
     fn create_float_test_matrix_4x4() -> FloatMatrix {
-        // 4x4 matrix (column-major) with some NaNs
-        // 1.0  5.0  9.0  13.0
-        // 2.0  NaN  10.0 NaN
-        // 3.0  6.0  NaN  14.0
-        // NaN  7.0  11.0 NaN
+        // 4x4 column-major matrix with NaNs inserted at positions where index % 5 == 0
         // first make array with 16 elements
         FloatMatrix::from_vec(
             (0..16)