Restored previous syntax, set frequency_array to be a numpy array by default

tupak/detector.py

@@ -67,7 +67,7 @@ class Interferometer(object):
         self.yarm_tilt = yarm_tilt
         self.power_spectral_density = power_spectral_density
         self.data = np.array([])
-        self.frequency_array = []
+        self.frequency_array = np.array([])
         self.sampling_frequency = None
         self.duration = None
 
@@ -90,11 +90,7 @@ class Interferometer(object):
     @property
     def frequency_mask(self):
         """Masking array for limiting the frequency band."""
-        frequencies_in_mask = []
-        for frequency in self.frequency_array:
-            if self.minimum_frequency < frequency < self.maximum_frequency:
-                frequencies_in_mask.append(frequency)
-        return frequencies_in_mask
+        return (self.frequency_array > self.minimum_frequency) & (self.frequency_array < self.maximum_frequency)
 
     @property
     def latitude(self):