use non-causal filter

Author: salman2135

src/explorepy/asr_processor.py

@@ -17,8 +17,7 @@
     asr_process
 )
 
-from explorepy.filters import ExGFilter
-
+from explorepy.filters import bp_filter
 
 logger = logging.getLogger(__name__)
 
@@ -137,7 +136,6 @@ def __init__(self, stream_proc, in_topic):
         self.instantiate_buffers()
         self.is_initialized = True
         self.lifecycle_state = State.STABLE
-        self.filter = None
 
     @property
     def cutoff(self):
@@ -190,7 +188,7 @@ def on_calib_data_received(self, packet):
             return
         self.calibration_data_input = np.append(
             self.calibration_data_input,
-            self.filter.apply(packet, in_place=False).get_data()[1],
+            packet.get_data()[1],
             axis=1,
         )
 
@@ -221,8 +219,10 @@ def clean_data(self):
             return
         if self.to_clean_ts[0][0] <= 1.0:
             return
+        filt_sig = bp_filter(self.to_clean.copy(), 45, 55, btype='bandstop', fs=self.sr)
+        filtered_data = bp_filter(filt_sig, .1, 40, fs=self.sr)
         try:
-            ret = asr_pipeline(self.to_clean, self.sr, self.ch_count, self._state)
+            ret = asr_pipeline(filtered_data, self.sr, self.ch_count, self._state)
             self.cleaned_data_available = True
             idx = np.searchsorted(self.to_clean_ts[0], self.last_cleaned_timestamp)
             self.cleaned_data = ret[:, idx:]
@@ -258,12 +258,6 @@ def start_calibration(self, calib_length: float = -1.0):
                          f"[{self._min_calibration_length},{self._max_calibration_length}]")
         logger.info(f"Starting ASR calibration for {self.calibration_length}s...")
         self.calib_started_at = time.time()
-        self.filter = ExGFilter(
-            cutoff_freq=(1, 45),
-            filter_type='bandpass',
-            s_rate=self.sr,
-            n_chan=self.ch_count,
-        )
         self.stream_processor.subscribe(self.on_calib_data_received, topic=self.in_topic)
 
     def stop_calibration(self):
@@ -276,7 +270,9 @@ def stop_calibration(self):
 
     def set_state_from_calibration_data(self, calib_data):
         self.lifecycle_state = State.CLEANING
-        cleaned, state = clean_calib_data(calib_data, self.sr)
+        filt_sig = bp_filter(calib_data, 45, 55, btype='bandstop', fs=self.sr)
+        filtered_data = bp_filter(filt_sig, .1, 40, self.sr)
+        cleaned, state = clean_calib_data(filtered_data, self.sr)
         if cleaned is None:
             self.calibration_data_available = False
             self.lifecycle_state = state

src/explorepy/filters.py

@@ -4,6 +4,7 @@
 import logging
 
 import numpy as np
+from scipy import signal
 from scipy.signal import (
     butter,
     iirfilter,
@@ -17,6 +18,13 @@
 logger = logging.getLogger(__name__)
 
 
+@staticmethod
+def bp_filter(exg, lf, hf, fs, btype='bandpass'):
+    N = 5
+    b, a = signal.butter(N, [lf, hf], btype=btype, fs=fs)
+    return signal.filtfilt(b, a, exg, axis=1)
+
+
 class ExGFilter:
     """Filter class for ExG signals"""
     def __init__(self, cutoff_freq, filter_type, s_rate, n_chan, order=5):