Computing transiton matrix directly during AOIScanStep creation. Computing probabilities and density inside TransitionMatrix class.

3 files changed, 43 insertions, 12 deletions

diff --git a/src/argaze/GazeAnalysis/TransitionMatrix.py b/src/argaze/GazeAnalysis/TransitionMatrix.py
index 6fd7a7b..dce61de 100644
--- a/src/argaze/GazeAnalysis/TransitionMatrix.py
+++ b/src/argaze/GazeAnalysis/TransitionMatrix.py
@@ -13,10 +13,11 @@ from dataclasses import dataclass, field
 from argaze import GazeFeatures
 
 import pandas
+import numpy
 
 @dataclass
 class AOIScanPathAnalyzer(GazeFeatures.AOIScanPathAnalyzer):
-    """Implementation of transition matrix probabilities and density algorithm as described in ...
+    """Implementation of transition matrix probabilities and density algorithm as described in Krejtz et al., 2014
     """
 
     def __post_init__(self):
@@ -28,13 +29,14 @@ class AOIScanPathAnalyzer(GazeFeatures.AOIScanPathAnalyzer):
 
         assert(len(aoi_scan_path) > 1)
 
-        sequence = []
+        # Sum transitions starting from each aoi
+        row_sum = aoi_scan_path.transition_matrix.apply(lambda row: row.sum(), axis=1)
 
-        for aoi_scan_step in aoi_scan_path:
+        # Editing transition matrix probabilities
+        # Note: when no transiton starts from an aoi, destination probabilites is equal to 1/S where S is the number of aois
+        transition_matrix_probabilities = aoi_scan_path.transition_matrix.apply(lambda row: row.apply(lambda p: p / row_sum[row.name] if row_sum[row.name] > 0 else 1 / row_sum.size), axis=1)
 
-            sequence.append(aoi_scan_step.aoi)
-
-        transition_matrix_probabilities = pandas.crosstab(pandas.Series(sequence[1:], name='to'), pandas.Series(sequence[:-1], name='from'), normalize='index')
+        # Calculate matrix density
         transition_matrix_density = (transition_matrix_probabilities != 0.).astype(int).sum(axis=1).sum() / transition_matrix_probabilities.size
 
         return transition_matrix_probabilities, transition_matrix_density
diff --git a/src/argaze/GazeFeatures.py b/src/argaze/GazeFeatures.py
index a098dc4..21841ac 100644
--- a/src/argaze/GazeFeatures.py
+++ b/src/argaze/GazeFeatures.py
@@ -548,18 +548,22 @@ AOIScanPathType = TypeVar('AOIScanPathType', bound="AOIScanPathType")
 # Type definition for type annotation convenience
 
 class AOIScanPath(list):
-    """List of aoi scan steps over successive AOI."""
+    """List of aoi scan steps over successive aoi."""
 
-    def __init__(self):
+    def __init__(self, expected_aois: list[str] = []):
 
         super().__init__()
         
+        self.__expected_aois = expected_aois
         self.__movements = TimeStampedGazeMovements()
         self.__current_aoi = ''
         self.__index = ord('A')
         self.__aoi_letter = {}
         self.__letter_aoi = {}
 
+        size = len(self.__expected_aois)
+        self.__transition_matrix = pandas.DataFrame(numpy.zeros((size, size)), index=self.__expected_aois, columns=self.__expected_aois)
+
     def __repr__(self):
         """String representation."""
 
@@ -593,11 +597,23 @@ class AOIScanPath(list):
         return sequence
 
     @property
+    def expected_aois(self):
+        """List of all expected aoi."""
+
+        return self.__expected_aois
+    
+    @property
     def current_aoi(self):
         """AOI name of aoi scan step under construction"""
 
         return self.__current_aoi
 
+    @property
+    def transition_matrix(self) -> pandas.DataFrame:
+        """Pandas DataFrame where indexes are transition departures and columns are transition destinations."""
+
+        return self.__transition_matrix
+
     def append_saccade(self, ts, saccade):
         """Append new saccade to aoi scan path."""
 
@@ -612,6 +628,10 @@ class AOIScanPath(list):
         .. warning::
            It could raise AOIScanStepError"""
 
+        if looked_aoi not in self.__expected_aois:
+
+            raise AOIScanStepError('AOI not expected', looked_aoi)
+
         # Is it fixation onto a new aoi?
         if looked_aoi != self.__current_aoi and len(self.__movements) > 0:
 
@@ -626,6 +646,12 @@ class AOIScanPath(list):
                 # Edit new step
                 new_step = AOIScanStep(self.__movements, self.__current_aoi, letter)
 
+                # Edit transition matrix
+                if len(self) > 0:
+
+                    # Increment [index: source, columns: destination] value
+                    self.__transition_matrix.loc[self[-1].aoi, self.__current_aoi,] += 1
+
                 # Append new step
                 super().append(new_step)
 
diff --git a/src/argaze/utils/demo_gaze_features_run.py b/src/argaze/utils/demo_gaze_features_run.py
index 736ffa9..50cf113 100644
--- a/src/argaze/utils/demo_gaze_features_run.py
+++ b/src/argaze/utils/demo_gaze_features_run.py
@@ -80,7 +80,7 @@ def main():
     identification_mode = 'I-DT'
 
     raw_scan_path = GazeFeatures.ScanPath()
-    aoi_scan_path = GazeFeatures.AOIScanPath()
+    aoi_scan_path = GazeFeatures.AOIScanPath(aoi_scene_projection.keys())
 
     tm = TransitionMatrix.AOIScanPathAnalyzer()
     tm_probabilities = pandas.DataFrame()
@@ -342,9 +342,11 @@ def main():
 
                     cv2.putText(aoi_matrix, f'Transition matrix density: {tm_density:.2f}', (20, window_size[1]-160), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 255), 1, cv2.LINE_AA)
                     
-                    for from_aoi, column in tm_probabilities.items():
+                    # Iterate over indexes (departures)
+                    for from_aoi, row in tm_probabilities.iterrows():
 
-                        for to_aoi, probability in column.items():
+                        # Iterate over columns (destinations)
+                        for to_aoi, probability in row.items():
 
                             if from_aoi != to_aoi and probability > 0.0:
 
@@ -396,7 +398,8 @@ def main():
                 # Write entropy
                 if enable_entropy_analysis:
 
-                    cv2.putText(aoi_matrix, f'Entropy: {entropy_analysis}', (20, window_size[1]-240), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 255), 1, cv2.LINE_AA)
+                    cv2.putText(aoi_matrix, f'Stationary entropy: {entropy_analysis[0]:.3f},', (20, window_size[1]-280), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 255), 1, cv2.LINE_AA)
+                    cv2.putText(aoi_matrix, f'Transition entropy: {entropy_analysis[1]:.3f},', (20, window_size[1]-240), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 255), 1, cv2.LINE_AA)
                     
             # Unlock gaze movement identification
             gaze_movement_lock.release()