refactor sampling module

amodem/sampling.py

@@ -43,7 +43,8 @@ class Sampler(object):
 
     def take(self, size):
         frame = np.zeros(size)
-
+        count = 0
+        try:
             for frame_index in range(size):
                 offset = self.offset
                 # offset = k + (j / self.resolution)
@@ -58,19 +59,17 @@ class Sampler(object):
 
                 self.offset += self.freq
                 frame[frame_index] = np.dot(coeffs, self.buff) * self.gain
+                count = frame_index + 1
+        except StopIteration:
+            pass
 
-        return frame
+        return frame[:count]
 
 
-if __name__ == '__main__':
+def resample(src, dst, df=0.0):
     import common
-    import sys
+    x = common.load(src)
-    df, = sys.argv[1:]
-    df = float(df)
-
-    x = common.load(sys.stdin)
     sampler = Sampler(x, Interpolator())
     sampler.freq += df
-    y = np.array(list(sampler))
+    y = sampler.take(len(x))
-    y = common.dumps(y)
+    dst.write(common.dumps(y))
-    sys.stdout.write(y)

scripts/resample.py

@@ -0,0 +1,4 @@
+from amodem.sampling import resample
+import sys
+
+resample(src=sys.stdin, dst=sys.stdout, df=float(sys.argv[1]))

tests/test_sampling.py

@@ -1,14 +1,22 @@
 from amodem import sampling
+from amodem import common
+
 import numpy as np
+from io import BytesIO
 
 
 def test_resample():
-    x = np.arange(300)
+    x = np.sin(2*np.pi * 10 * np.linspace(0, 1, 1001))
-    s = sampling.Sampler(x, interp=sampling.Interpolator())
+    src = BytesIO(common.dumps(x))
-    y = s.take(len(x) - s.interp.width - 1)
+    dst = BytesIO()
-
+    sampling.resample(src=src, dst=dst, df=0.0)
+    y = common.loads(dst.getvalue())
     err = x[1:len(y)+1] - y
-    assert np.max(np.abs(err)) < 1e-10
+    assert np.max(np.abs(err)) < 1e-4
+
+    dst = BytesIO()
+    sampling.resample(src=BytesIO('\x00\x00'), dst=dst, df=0.0)
+    assert dst.tell() == 0
 
 
 def test_coeffs():