From 14e0a302c569c23a42b51c851463dfc7bd93b8aa Mon Sep 17 00:00:00 2001
From: SeanvdMeer <18538762+minisean@users.noreply.github.com>
Date: Mon, 23 Jun 2025 00:51:06 +0200
Subject: [PATCH 1/2] Reverted change to _calculate_intersection as it
 introduced a bug.

---
 .../intrf_state_classification.py             | 69 +++++--------------
 1 file changed, 17 insertions(+), 52 deletions(-)

diff --git a/src/qce_interp/interface_definitions/intrf_state_classification.py b/src/qce_interp/interface_definitions/intrf_state_classification.py
index 1471222..302c339 100644
--- a/src/qce_interp/interface_definitions/intrf_state_classification.py
+++ b/src/qce_interp/interface_definitions/intrf_state_classification.py
@@ -266,58 +266,23 @@ def _calculate_intersection(coef1: Vec2D, intercept1: float, coef2: Vec2D, inter
         """
         :return: Intersection point of two linear equations defined by coefficients and intercepts.
         """
-        """
-        Compute the (x, y) coordinates where the two lines
-
-            coef1.x * x + coef1.y * y + intercept1 = 0
-            coef2.x * x + coef2.y * y + intercept2 = 0
-
-        intersect.
-
-        Parameters
-        ----------
-        coef1, coef2 : Vec2D
-            Line coefficients (a, b), i.e. normal-vector components.
-        intercept1, intercept2 : float
-            Line intercepts *c* (constant terms).
-
-        Returns
-        -------
-        Vec2D
-            Intersection point.
-
-        Raises
-        ------
-        ValueError
-            If the lines are parallel (det ≈ 0) or coincident, so no unique
-            intersection exists.
-        """
-        # Unpack coefficients
-        a1, b1 = coef1.x, coef1.y
-        a2, b2 = coef2.x, coef2.y
-
-        # Determinant of the 2×2 system
-        det: float = a1 * b2 - a2 * b1
-        tol: float = 1e-12
-
-        if abs(det) < tol:
-            # Parallel or coincident — inspect intercepts for distinction
-            if abs(a1 * intercept2 - a2 * intercept1) < tol and \
-               abs(b1 * intercept2 - b2 * intercept1) < tol:
-                # raise ValueError("Lines are coincident; infinite intersections.")
-                return Vec2D(x=0.0, y=0.0)
-            # raise ValueError("Lines are parallel; no unique intersection.")
-            return Vec2D(x=0.0, y=0.0)
-
-        # Solve A x = b  (A = [[a1, b1], [a2, b2]], b = [-c1, -c2])
-        A = np.array([
-            [a1, b1],
-            [a2, b2],
-        ], dtype=float)
-        b = np.array([-intercept1, -intercept2], dtype=float)
-        x, y = np.linalg.solve(A, b)
-
-        return Vec2D.from_vector(np.array([x, y]))
+        denominator: float = (-coef1.x / coef1.y + coef2.x / coef2.y)
+        numerator: float = (-intercept2 / coef2.y + intercept1 / coef1.y)
+        # Deal with possible zero-division error
+        if denominator != 0:
+            _x: float = numerator / denominator
+        elif denominator == 0 and numerator == 0:
+            _x: float = 1.0
+        else:
+            warn(f"[ZeroDivisionError] During intersect calculation of {coef1} and {coef2}.")
+            denominator = 1e-6
+            _x: float = numerator / denominator
+
+        _y: float = -coef1.x / coef1.y * _x - intercept1 / coef1.y
+        return Vec2D(
+            x=_x,
+            y=_y,
+        )
 
     @staticmethod
     def _calculate_intersection_binary_case(coef1: Vec2D, intercept1: float):

From bda54e68010990cb760bbfeb90ccc2574a8179b9 Mon Sep 17 00:00:00 2001
From: SeanvdMeer <18538762+minisean@users.noreply.github.com>
Date: Fri, 27 Jun 2025 16:30:13 +0200
Subject: [PATCH 2/2] Added option to enforce binary classification plotting

---
 .../visualization/plot_state_classification.py        | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/qce_interp/visualization/plot_state_classification.py b/src/qce_interp/visualization/plot_state_classification.py
index 8033d47..3e71fbc 100644
--- a/src/qce_interp/visualization/plot_state_classification.py
+++ b/src/qce_interp/visualization/plot_state_classification.py
@@ -8,6 +8,7 @@
 from qce_interp.utilities.geometric_definitions import Vec2D, Polygon, euclidean_distance
 from qce_interp.interface_definitions.intrf_state_classification import (
     IStateAcquisitionContainer,
+    StateAcquisitionContainer,
     StateBoundaryKey,
     DirectedStateBoundaryKey,
     DecisionBoundaries,
@@ -524,7 +525,7 @@ def plot_decision_region(state_classifier: IStateAcquisitionContainer, **kwargs)
     return fig, ax
 
 
-def plot_state_classification(state_classifier: IStateAcquisitionContainer, **kwargs) -> IFigureAxesPair:
+def plot_state_classification(state_classifier: IStateAcquisitionContainer, use_binary_classification: bool = False, **kwargs) -> IFigureAxesPair:
     """
     Creates a plot visualizing state classification and decision boundaries.
 
@@ -532,6 +533,14 @@ def plot_state_classification(state_classifier: IStateAcquisitionContainer, **kw
     :param kwargs: Additional keyword arguments for plot customization.
     :return: Tuple containing the figure and axes of the plot.
     """
+    if use_binary_classification:
+        state_classifier = StateAcquisitionContainer.from_state_acquisitions(
+            acquisitions=[
+                state_classifier.get_state_acquisition(state=StateKey.STATE_0),
+                state_classifier.get_state_acquisition(state=StateKey.STATE_1),
+            ]
+        )
+
     decision_boundaries: DecisionBoundaries = state_classifier.classification_boundaries
     kwargs[SubplotKeywordEnum.AXES_FORMAT.value] = IQAxesFormat()
     kwargs[SubplotKeywordEnum.LABEL_FORMAT.value] = LabelFormat(