From 42094bea274e7ff7a7fd3e0946fd620a8522dc46 Mon Sep 17 00:00:00 2001
From: eminSerin <emin.serin@charite.de>
Date: Sun, 21 Apr 2024 19:00:27 +0200
Subject: [PATCH] - Add function to check if a given matrix symmetric with
 tolerance. - Fix minor bug in NBSPredict_predict.

---
 src/NBSPredict_predict.m           |  3 ++-
 src/io/MatrixVectorizer.m          |  2 +-
 src/io/is_symmetric.m              | 41 ++++++++++++++++++++++++++++++
 src/io/shrinkMat.m                 |  2 +-
 test/networks/networks/gen_BAnet.m |  2 +-
 5 files changed, 46 insertions(+), 4 deletions(-)
 create mode 100644 src/io/is_symmetric.m

diff --git a/src/NBSPredict_predict.m b/src/NBSPredict_predict.m
index 119af43..23ce32c 100644
--- a/src/NBSPredict_predict.m
+++ b/src/NBSPredict_predict.m
@@ -114,7 +114,8 @@
 end
 
 % Shrink connectivity matrices into edge matrices.
-X = connData(model.preprocess.edgeIdx)'; 
+X = shrinkMat(connData);
+
 
 % Predicts label using given data.
 if ~isempty(model.preprocess.scaler)
diff --git a/src/io/MatrixVectorizer.m b/src/io/MatrixVectorizer.m
index a76a838..3d0ce5f 100644
--- a/src/io/MatrixVectorizer.m
+++ b/src/io/MatrixVectorizer.m
@@ -98,7 +98,7 @@
             else
                 for i = 1:subjects
                     cMat = data(:,:,i); % Select current matrix.
-                    if ~issymmetric(cMat)
+                    if ~is_symmetric(cMat)
                         warning('Given matrix is not symmetric! Data index: %d', i)
                     end
                     edgeMat(i,:)=cMat(obj.edgeIdx); % extract edge values.
diff --git a/src/io/is_symmetric.m b/src/io/is_symmetric.m
new file mode 100644
index 0000000..d35eb7f
--- /dev/null
+++ b/src/io/is_symmetric.m
@@ -0,0 +1,41 @@
+function isSymmetric = is_symmetric(matrix, tolerance)
+% IS_SYMMETRIC Checks if a given matrix is symmetric within a specified tolerance.
+%
+% Syntax:
+%   isSymmetric = is_symmetric(matrix, tolerance)
+%
+% Input Arguments:
+%   matrix - A square matrix to be checked for symmetry.
+%   tolerance - A scalar value specifying the tolerance for the symmetry check. 
+%               If not provided, the default value is 1e-15.
+%
+% Output Argument:
+%   isSymmetric - A logical value indicating whether the matrix is symmetric 
+%                 within the specified tolerance. Returns true if the matrix 
+%                 is symmetric and false otherwise.
+%
+% Example:
+%   matrix = [1, 2; 2, 1];
+%   isSymmetric = is_symmetric(matrix, 1e-15);
+%
+%   This will return true as the matrix is symmetric within the tolerance of 1e-15.
+%
+% Note:
+%   The function first checks if the matrix is square. If not, it returns false. 
+%   Then it calculates the absolute difference between the matrix and its transpose. 
+%   If all elements in the difference matrix are within the tolerance, it returns true. 
+%   Otherwise, it returns false.
+%
+if nargin < 2
+    tolerance = 1e-15;
+if size(matrix, 1) ~= size(matrix, 2)
+    isSymmetric = false;
+    return;
+end
+
+% Calculate the difference between the matrix and its transpose
+diffMatrix = abs(matrix - matrix');
+
+% Check if all elements in the difference matrix are within the tolerance
+isSymmetric = all(all(diffMatrix <= tolerance));
+end
\ No newline at end of file
diff --git a/src/io/shrinkMat.m b/src/io/shrinkMat.m
index c6c409f..1b2ae2f 100644
--- a/src/io/shrinkMat.m
+++ b/src/io/shrinkMat.m
@@ -38,7 +38,7 @@
 else
     for i = 1:subjects
         cMat = data(:,:,i); % Select current matrix.
-        if ~issymmetric(cMat)
+        if ~is_symmetric(cMat)
             warning('Given matrix is not symmetric! Data index: %d', i)
         end
         edgeMat(i,:)=cMat(edgeIdx); % extract edge values.
diff --git a/test/networks/networks/gen_BAnet.m b/test/networks/networks/gen_BAnet.m
index e720e1e..17cfbc1 100644
--- a/test/networks/networks/gen_BAnet.m
+++ b/test/networks/networks/gen_BAnet.m
@@ -65,7 +65,7 @@
     eIdx = eIdx + m*2;
 end
 
-if ~issymmetric(g)
+if ~is_symmetric(g)
     error('Network is not symmetric. Please run the function again.');
 end