From b261f1b10282be9075c7a59dd7042efadc83dafd Mon Sep 17 00:00:00 2001
From: Roman Zeyde <roman.zeyde@gmail.com>
Date: Sat, 12 Jul 2014 16:18:06 +0300
Subject: [PATCH] simplify common.iterate()

---
 common.py      | 29 ++++++++++++-----------------
 recv.py        |  4 ++--
 sigproc.py     |  2 +-
 test_common.py | 25 ++++++++++++++++---------
 4 files changed, 31 insertions(+), 29 deletions(-)

diff --git a/common.py b/common.py
index 5b12694..12dc6eb 100644
--- a/common.py
+++ b/common.py
@@ -1,4 +1,5 @@
 import functools
+import itertools
 import numpy as np
 
 import logging
@@ -59,25 +60,19 @@ def dumps(sym, n=1):
     return data * n
 
 
-def iterate(data, bufsize, offset=0, advance=1, func=None):
-    assert bufsize > 0
-    assert offset >= 0
-    assert advance > 0
-    buf = np.zeros(bufsize)
-    buf_index = 0
-    for data_index, value in enumerate(data):
-        if data_index < offset:
-            continue
+def iterate(data, size, func=None):
+    offset = 0
+    data = iter(data)
 
-        buf[buf_index] = value
-        buf_index += 1
+    while True:
+        buf = list(itertools.islice(data, size))
+        if len(buf) < size:
+            return
 
-        if buf_index == bufsize:
-            result = func(buf) if func else buf
-            yield offset, result
-            buf[:-advance] = buf[advance:]
-            buf_index = max(0, buf_index - advance)
-            offset += advance
+        buf = np.array(buf)
+        result = func(buf) if func else buf
+        yield offset, result
+        offset += size
 
 
 class Splitter(object):
diff --git a/recv.py b/recv.py
index 441eca9..5359ade 100755
--- a/recv.py
+++ b/recv.py
@@ -28,7 +28,7 @@ CARRIER_THRESHOLD = int(0.95 * CARRIER_DURATION)
 
 def detect(x, freq):
     counter = 0
-    for offset, buf in iterate(x, Nsym, advance=Nsym):
+    for offset, buf in iterate(x, Nsym):
         coeff = sigproc.coherence(buf, Fc)
         if abs(coeff) > COHERENCE_THRESHOLD:
             counter += 1
@@ -185,7 +185,7 @@ def main(fname):
     if data_bits is None:
         log.warning('Training failed!')
     else:
-        data = iterate(data_bits, bufsize=8, advance=8, func=to_byte)
+        data = iterate(data_bits, 8, func=to_byte)
         data = ''.join(c for _, c in data)
         import ecc
         data = ecc.decode(data)
diff --git a/sigproc.py b/sigproc.py
index 049361e..1d2c499 100644
--- a/sigproc.py
+++ b/sigproc.py
@@ -91,7 +91,7 @@ def extract_symbols(x, freq, offset=0):
     Hc = exp_iwt(-freq, common.Nsym) / (0.5*common.Nsym)
     func = lambda y: np.dot(Hc, y)
 
-    iterator = common.iterate(x, common.Nsym, advance=common.Nsym, func=func)
+    iterator = common.iterate(x, common.Nsym, func=func)
     for _, symbol in iterator:
         yield symbol
 
diff --git a/test_common.py b/test_common.py
index 384f7ce..3f985cc 100644
--- a/test_common.py
+++ b/test_common.py
@@ -1,20 +1,26 @@
 import common
 import numpy as np
 
+
 def iterlist(x, *args, **kwargs):
     x = np.array(x)
-    return [(offset, list(buf)) for offset, buf in common.iterate(x, *args, **kwargs)]
+    return list((i, list(x)) for i, x in common.iterate(x, *args, **kwargs))
+
 
 def test_iterate():
     N = 10
-    assert iterlist(range(N), 1) == [(i, [i]) for i in range(N)]
-    assert iterlist(range(N), 1) == [(i, [i]) for i in range(N)]
-    assert iterlist(range(N), 2) == [(i, [i, i+1]) for i in range(N-1)]
-    assert iterlist(range(N), 3) == [(i, [i, i+1, i+2]) for i in range(N-2)]
-    assert iterlist(range(N), 3, advance=2) == [(i, [i, i+1, i+2]) for i in range(0, N-2, 2)]
-    assert iterlist(range(N), 3, advance=3) == [(i, [i, i+1, i+2]) for i in range(0, N-2, 3)]
-    assert iterlist(range(N), 2, offset=5) == [(i, [i, i+1]) for i in range(5, N-1)]
-    assert iterlist(range(N), 1, func=lambda b: -b) == [(i, [-i]) for i in range(N)]
+    assert iterlist(range(N), 1) == [
+        (i, [i]) for i in range(N)]
+
+    assert iterlist(range(N), 2) == [
+        (i, [i, i+1]) for i in range(0, N-1, 2)]
+
+    assert iterlist(range(N), 3) == [
+        (i, [i, i+1, i+2]) for i in range(0, N-2, 3)]
+
+    assert iterlist(range(N), 1, func=lambda b: -b) == [
+        (i, [-i]) for i in range(N)]
+
 
 def test_split():
     L = [(i*2, i*2+1) for i in range(10)]
@@ -30,6 +36,7 @@ def test_split():
         except IndexError as e:
             assert e.args == (i,)
 
+
 def test_icapture():
     x = range(100)
     y = []