correct signed contrast computation

iblrig/base_choice_world.py

@@ -966,7 +966,7 @@ def get_subject_training_info(self):
 
     def compute_performance(self):
         """Aggregate the trials table to compute the performance of the mouse on each contrast."""
-        self.trials_table['signed_contrast'] = self.trials_table.contrast * self.trials_table.position
+        self.trials_table['signed_contrast'] = self.trials_table.contrast * np.sign(self.trials_table.position)
         performance = self.trials_table.groupby(['signed_contrast']).agg(
             last_50_perf=pd.NamedAgg(column='trial_correct', aggfunc=lambda x: np.sum(x[np.maximum(-50, -x.size) :]) / 50),
             ntrials=pd.NamedAgg(column='trial_correct', aggfunc='count'),