Python 3 compatibility: imap->map, izip->zip, xrange->range (#9)

pysstv/color.py

@@ -1,6 +1,12 @@
 #!/usr/bin/env python
 
 from __future__ import division
+try:  # python 2/3 compatibility
+    xrange  # will fail in python 3
+except NameError:
+    pass
+else:
+    range = xrange
 from pysstv.sstv import byte_to_freq, FREQ_BLACK, FREQ_WHITE, FREQ_VIS_START
 from pysstv.grayscale import GrayscaleSSTV
 from itertools import chain
@@ -18,7 +24,7 @@ class ColorSSTV(GrayscaleSSTV):
         for index in self.COLOR_SEQ:
             for item in self.before_channel(index):
                 yield item
-            for col in xrange(self.WIDTH):
+            for col in range(self.WIDTH):
                 pixel = image[col, line]
                 freq_pixel = byte_to_freq(pixel[index])
                 yield freq_pixel, msec_pixel
@@ -92,7 +98,7 @@ class Robot36(ColorSSTV):
         self.yuv = self.image.convert('YCbCr').load()
 
     def encode_line(self, line):
-        pixels = [self.yuv[col, line] for col in xrange(self.WIDTH)]
+        pixels = [self.yuv[col, line] for col in range(self.WIDTH)]
         channel = (line % 2) + 1
         y_pixel_time = self.Y_SCAN / self.WIDTH
         uv_pixel_time = self.C_SCAN / self.WIDTH
@@ -102,19 +108,19 @@ class Robot36(ColorSSTV):
                 [(self.INTER_CH_FREQS[channel], self.INTER_CH_GAP),
                     (FREQ_VIS_START, self.PORCH)],
                 ((byte_to_freq(p[channel]), uv_pixel_time) for p in pixels))
-		
+
 
 class PasokonP3(ColorSSTV):
     """
-      [ VIS code or horizontal sync here ]  
-      Back porch - 5 time units of black (1500 Hz).    
-      Red component - 640 pixels of 1 time unit each.    
-      Gap - 5 time units of black.   
-      Green component - 640 pixels of 1 time unit each.  
-      Gap - 5 time units of black.    
-      Blue component - 640 pixels of 1 time unit each.   
-      Front porch - 5 time units of black.   
-      Horizontal Sync - 25 time units of 1200 Hz.
+    [ VIS code or horizontal sync here ]
+    Back porch - 5 time units of black (1500 Hz).
+    Red component - 640 pixels of 1 time unit each.
+    Gap - 5 time units of black.
+    Green component - 640 pixels of 1 time unit each.
+    Gap - 5 time units of black.
+    Blue component - 640 pixels of 1 time unit each.
+    Front porch - 5 time units of black.
+    Horizontal Sync - 25 time units of 1200 Hz.
     """
     TIMEUNIT = 1000/4800. # ms
     COLOR_SEQ = (RED, GREEN, BLUE)

pysstv/grayscale.py

@@ -1,6 +1,13 @@
 #!/usr/bin/env python
 
 from __future__ import division
+
+try:  # python 2/3 compatibility
+    xrange  # will fail in python 3
+except NameError:
+    pass
+else:
+    range = xrange
 from pysstv.sstv import SSTV, byte_to_freq
 
 
@@ -9,7 +16,7 @@ class GrayscaleSSTV(SSTV):
         self.pixels = self.image.convert('LA').load()
 
     def gen_image_tuples(self):
-        for line in xrange(self.HEIGHT):
+        for line in range(self.HEIGHT):
             for item in self.horizontal_sync():
                 yield item
             for item in self.encode_line(line):
@@ -18,7 +25,7 @@ class GrayscaleSSTV(SSTV):
     def encode_line(self, line):
         msec_pixel = self.SCAN / self.WIDTH
         image = self.pixels
-        for col in xrange(self.WIDTH):
+        for col in range(self.WIDTH):
             pixel = image[col, line]
             freq_pixel = byte_to_freq(pixel[0])
             yield freq_pixel, msec_pixel

pysstv/sstv.py

@@ -4,7 +4,21 @@ from __future__ import division, with_statement
 from math import sin, pi
 from random import random
 from contextlib import closing
-from itertools import imap, izip, cycle, chain
+try:
+    import itertools.imap as map  # python 2
+except ImportError:
+    pass  # python 3
+try:
+    import itertools.izip as zip  # python 2
+except ImportError:
+    pass  # python 3
+from itertools import cycle, chain
+try:  # python 2/3 compatibility
+    xrange  # will fail in python 3
+except NameError:
+    pass
+else:
+    range = xrange
 from array import array
 import wave
 
@@ -46,7 +60,7 @@ class SSTV(object):
         data = array(fmt, self.gen_samples())
         if self.nchannels != 1:
             data = array(fmt, chain.from_iterable(
-                izip(*([data] * self.nchannels))))
+                zip(*([data] * self.nchannels))))
         with closing(wave.open(filename, 'wb')) as wav:
             wav.setnchannels(self.nchannels)
             wav.setsampwidth(self.bits // 8)
@@ -64,8 +78,8 @@ class SSTV(object):
         amp = max_value // 2
         lowest = -amp
         highest = amp - 1
-        alias_cycle = cycle((alias * (random() - 0.5) for _ in xrange(1024)))
-        for value, alias_item in izip(self.gen_values(), alias_cycle):
+        alias_cycle = cycle((alias * (random() - 0.5) for _ in range(1024)))
+        for value, alias_item in zip(self.gen_values(), alias_cycle):
             sample = int(value * amp + alias_item)
             yield (lowest if sample <= lowest else
                 sample if sample <= highest else highest)
@@ -85,7 +99,7 @@ class SSTV(object):
             samples += spms * msec
             tx = int(samples)
             freq_factor = freq * factor
-            for sample in xrange(tx):
+            for sample in range(tx):
                 yield sin(sample * freq_factor + offset)
             offset += (sample + 1) * freq_factor
             samples -= tx
@@ -104,7 +118,7 @@ class SSTV(object):
         yield FREQ_SYNC, MSEC_VIS_BIT  # start bit
         vis = self.VIS_CODE
         num_ones = 0
-        for _ in xrange(7):
+        for _ in range(7):
             bit = vis & 1
             vis >>= 1
             num_ones += bit
@@ -115,8 +129,8 @@ class SSTV(object):
         yield FREQ_SYNC, MSEC_VIS_BIT  # stop bit
         for freq_tuple in self.gen_image_tuples():
             yield freq_tuple
-        for fskid_byte in imap(ord, self.fskid_payload):
-            for _ in xrange(6):
+        for fskid_byte in map(ord, self.fskid_payload):
+            for _ in range(6):
                 bit = fskid_byte & 1
                 fskid_byte >>= 1
                 bit_freq = FREQ_FSKID_BIT1 if bit == 1 else FREQ_FSKID_BIT0