common: move izip() from recv module and refactor it a bit

amodem/common.py

@@ -93,6 +93,13 @@ def take(iterable, n):
     return np.array(list(itertools.islice(iterable, n)))
 
 
+# "Python 3" zip re-implementation for Python 2
+def izip(iterables):
+    iterables = [iter(iterable) for iterable in iterables]
+    while True:
+        yield tuple([next(iterable) for iterable in iterables])
+
+
 class Dummy(object):
 
     def __getattr__(self, name):

amodem/recv.py

@@ -195,7 +195,7 @@ class Receiver(object):
         self.stats['rx_start'] = time.time()
 
         log.info('Starting demodulation: %s', modem)
-        for i, block in enumerate(izip(streams)):  # block per frequency
+        for i, block in enumerate(common.izip(streams)):  # block per frequency
             for bits in block:
                 self.stats['rx_bits'] = self.stats['rx_bits'] + len(bits)
                 yield bits
@@ -264,12 +264,6 @@ class Receiver(object):
         self.plt.title(title)
 
 
-def izip(streams):
-    iters = [iter(s) for s in streams]
-    while True:
-        yield [next(i) for i in iters]
-
-
 def main(args):
     reader = stream.Reader(args.input, data_type=common.loads)
     signal = itertools.chain.from_iterable(reader)

tests/test_common.py

@@ -60,3 +60,8 @@ def test_saturation():
         assert False
     except common.SaturationError as e:
         assert e.args == (max(x),)
+
+def test_izip():
+    x = range(10)
+    y = range(-10, 0)
+    assert list(common.izip([x, y])) == list(zip(x, y))