Refactoring FixationIdentifier to handle it as an iterator.

2 files changed, 49 insertions, 21 deletions

diff --git a/src/argaze/GazeFeatures.py b/src/argaze/GazeFeatures.py
index bb72583..2f1d167 100644
--- a/src/argaze/GazeFeatures.py
+++ b/src/argaze/GazeFeatures.py
@@ -45,19 +45,16 @@ class TimeStampedFixations(DataStructures.TimeStampedBuffer):
 class FixationIdentifier():
     """Abstract class to define what should provide a fixation identifier"""
 
-    fixations = TimeStampedFixations()
-    saccades = DataStructures.TimeStampedBuffer()
-
-    def identify(self, ts_gaze_positions):
-        raise NotImplementedError('identify() method not implemented')
-
     def __init__(self, ts_gaze_positions: TimeStampedGazePositions):
 
         if type(ts_gaze_positions) != TimeStampedGazePositions:
             raise ValueError('argument must be a TimeStampedGazePositions')
 
-        # do identification on a copy
-        self.identify(ts_gaze_positions.copy())
+    def __iter__(self):
+        raise NotImplementedError('__iter__() method not implemented')
+
+    def __next__(self):
+        raise NotImplementedError('__next__() method not implemented')
 
 class DispersionBasedFixationIdentifier(FixationIdentifier):
     """Implementation of the I-DT algorithm as described in:
@@ -70,10 +67,13 @@ class DispersionBasedFixationIdentifier(FixationIdentifier):
 
     def __init__(self, ts_gaze_positions, dispersion_threshold = 10, duration_threshold = 100):
 
+        super().__init__(ts_gaze_positions)
+
         self.__dispersion_threshold = dispersion_threshold
         self.__duration_threshold = duration_threshold
 
-        super().__init__(ts_gaze_positions)
+        # process identification on a copy
+        self.__ts_gaze_positions = ts_gaze_positions.copy()
 
     def __getEuclideanDispersion(self, ts_gaze_positions_list):
         """Euclidian dispersion algorithm"""
@@ -102,13 +102,17 @@ class DispersionBasedFixationIdentifier(FixationIdentifier):
 
         return (max(x_list) - min(x_list)) + (max(y_list) - min(y_list))
 
-    def identify(self, ts_gaze_positions):
+    def __iter__(self):
+        """Start fixation identification"""
+        return self
+
+    def __next__(self):
 
         # while there are 2 gaze positions at least
-        while len(ts_gaze_positions) >= 2:
+        if len(self.__ts_gaze_positions) >= 2:
 
             # copy remaining timestamped gaze positions
-            remaining_ts_gaze_positions = ts_gaze_positions.copy()
+            remaining_ts_gaze_positions = self.__ts_gaze_positions.copy()
 
             # select timestamped gaze position until a duration threshold
             (ts_start, gaze_position_start) = remaining_ts_gaze_positions.pop_first()
@@ -128,13 +132,12 @@ class DispersionBasedFixationIdentifier(FixationIdentifier):
             # how much gaze is dispersed ?
             dispersion, cx, cy = self.__getEuclideanDispersion(ts_gaze_positions_list)
 
-
             # little dispersion
             if dispersion <= self.__dispersion_threshold:
 
                 # remove selected gaze positions
                 for gp in ts_gaze_positions_list:
-                    ts_gaze_positions.pop_first()
+                    self.__ts_gaze_positions.pop_first()
 
                 # are next gaze positions not too dispersed ?
                 while len(remaining_ts_gaze_positions) > 0:
@@ -157,7 +160,7 @@ class DispersionBasedFixationIdentifier(FixationIdentifier):
                     cy = new_cy
 
                     # remove selected gaze position
-                    ts_gaze_positions.pop_first()
+                    self.__ts_gaze_positions.pop_first()
 
                 # we have a new fixation
                 ts_list = [ts for (ts, gp) in ts_gaze_positions_list]
@@ -168,9 +171,19 @@ class DispersionBasedFixationIdentifier(FixationIdentifier):
 
                 if duration > 0:
 
-                    # append fixation to timestamped buffer
-                    self.fixations[ts_list[0]] = Fixation(duration, dispersion, cx, cy)
+                    # return timestamp and fixation
+                    return ts_list[0], Fixation(duration, dispersion, cx, cy)
+
+                return -1, None
 
             # dispersion too wide : consider next gaze position
             else:
-                ts_gaze_positions.pop_first()
+                self.__ts_gaze_positions.pop_first()
+
+            # if no fixation found, go to next
+            return -1, None
+
+        else:
+            raise StopIteration
+
+        return -1, None
diff --git a/src/argaze/utils/export_tobii_segment_fixations.py b/src/argaze/utils/export_tobii_segment_fixations.py
index 4181c77..d40c4d3 100644
--- a/src/argaze/utils/export_tobii_segment_fixations.py
+++ b/src/argaze/utils/export_tobii_segment_fixations.py
@@ -6,7 +6,7 @@ import os
 
 from argaze import GazeFeatures
 from argaze.TobiiGlassesPro2 import TobiiEntities
-
+from argaze.utils import MiscFeatures
 
 def main():
     """
@@ -64,11 +64,26 @@ def main():
         print(f'Duration threshold: {args.duration_threshold}')
 
         fixation_analyser = GazeFeatures.DispersionBasedFixationIdentifier(generic_ts_gaze_positions, args.dispersion_threshold, args.duration_threshold)
+        fixations = GazeFeatures.TimeStampedFixations()
+
+        # Start fixation identification
+        MiscFeatures.printProgressBar(0, int(tobii_segment_video.get_duration()*1000), prefix = 'Progress:', suffix = 'Complete', length = 100)
+
+        for ts, item in fixation_analyser:
+
+            if item == None:
+                continue
+
+            if item.get_type() == 'Fixation':
+
+                fixations[ts] = item
+
+                MiscFeatures.printProgressBar(ts, int(tobii_segment_video.get_duration()*1000), prefix = 'Progress:', suffix = 'Complete', length = 100)
 
-        print(f'{len(fixation_analyser.fixations)} fixations found')
+        print(f'\n{len(fixations)} fixations found')
 
         # Export fixations analysis results
-        fixation_analyser.fixations.export_as_json(fixations_filepath)
+        fixations.export_as_json(fixations_filepath)
 
         print(f'Fixations saved into {fixations_filepath}')