Merge branch 'save-interpolation-parameters' into 'master'

Save interpolation order

See merge request !15

lisainstrument/instrument.py

@@ -164,38 +164,29 @@ class Instrument:
         self.init_aafilter(aafilter)
 
     def init_interpolation(self, interpolation):
-        """Initialize interpolation."""
+        """Initialize or design the interpolation function.
+
+        We support no interpolation, a custom interpolation function, or Lagrange interpolation.
+
+        Args:
+            parameters: see `interpolation` docstring in `__init__()`
+        """
         if interpolation is None:
             logging.info("Disabling interpolation")
+            self.interpolation_order = None
             self.interpolate = lambda x, _: x
         elif callable(interpolation):
             logging.info("Using user-provided interpolation function")
+            self.interpolation_order = None
             self.interpolate = lambda x, shift: x if numpy.isscalar(x) else interpolation(x, shift)
         else:
-            logging.info("Designing interpolation function")
-            self.interpolate = lambda x, shift: x if numpy.isscalar(x) \
-                else Instrument.design_interpolation(interpolation)(x, shift)
-
-    @staticmethod
-    def design_interpolation(parameters):
-        """Design the interpolation function.
-
-        We currently support Lagrange interpolation.
-
-        Args:
-            parameters: see `interpolation` docstring in `__init__()`
-
-        Returns:
-            A function which interpolates data.
-        """
-        method = parameters[0]
-        if method == 'lagrange':
-            logging.debug("Using Lagrange interpolations")
-            order = parameters[1]
-            logging.debug("Lagrange interpolation order is %s", order)
-            return lambda x, shift: dsp.timeshift(x, shift, order)
-
-        raise ValueError(f"invalid interpolation parameters '{parameters}'")
+            method = str(interpolation[0])
+            if method == 'lagrange':
+                self.interpolation_order = int(interpolation[1])
+                logging.debug("Using Lagrange interpolation of order %s", self.interpolation_order)
+                self.interpolate = lambda x, shift: \
+                    x if numpy.isscalar(x) else dsp.timeshift(x, shift, self.interpolation_order)
+            raise ValueError(f"invalid interpolation parameters '{interpolation}'")
 
     def init_aafilter(self, aafilter):
         """Initialize antialiasing filter and downsampling."""