From 6e3494586af34919f2afdd2e0604d09dee916571 Mon Sep 17 00:00:00 2001
From: Robert Smallshire <robert@smallshire.org.uk>
Date: Tue, 5 May 2015 13:30:32 +0200
Subject: [PATCH] Remove Python 2.7 crutch for izip and izip_longest

---
 segpy/packer.py      |  5 +++--
 segpy/portability.py |  9 ---------
 segpy/reader.py      |  1 -
 segpy/toolkit.py     | 13 ++++++-------
 segpy/util.py        |  4 +---
 5 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/segpy/packer.py b/segpy/packer.py
index 0b4be2e..b8de859 100644
--- a/segpy/packer.py
+++ b/segpy/packer.py
@@ -1,7 +1,8 @@
 from collections import OrderedDict
 from struct import Struct
+from itertools import zip_longest
+
 from segpy.datatypes import SEG_Y_TYPE_TO_CTYPE
-from segpy.portability import izip_longest
 from segpy.util import pairwise, intervals_partially_overlap, complementary_intervals
 
 
@@ -89,7 +90,7 @@ def compile_struct(header_format_class, length_in_bytes=None, endian='>'):
     # Create a format string usable with the struct module
     format_chunks = [endian]
     representative_fields = (fields[0] for fields in offset_to_fields.values())
-    for gap_interval, field in izip_longest(gap_intervals, representative_fields, fillvalue=None):
+    for gap_interval, field in zip_longest(gap_intervals, representative_fields, fillvalue=None):
         gap_length = len(gap_interval)
         if gap_length > 0:
             format_chunks.append('x' * gap_length)
diff --git a/segpy/portability.py b/segpy/portability.py
index ccd0979..243fb86 100644
--- a/segpy/portability.py
+++ b/segpy/portability.py
@@ -4,15 +4,6 @@ import sys
 EMPTY_BYTE_STRING = b'' if sys.version_info >= (3, 0) else ''
 
 
-if sys.version_info >= (3, 0):
-    izip = zip
-    from itertools import zip_longest as izip_longest
-else:
-    from itertools import (izip, izip_longest)
-    izip = izip                  # Keep the static analyzer happy
-    izip_longest = izip_longest  # Keep the static analyzer happy
-
-
 if sys.version_info >= (3, 0):
     def four_bytes(byte_str):
         a, b, c, d = byte_str[:4]
diff --git a/segpy/reader.py b/segpy/reader.py
index 3a9f727..7e67052 100644
--- a/segpy/reader.py
+++ b/segpy/reader.py
@@ -2,7 +2,6 @@ from __future__ import print_function
 from segpy.encoding import ASCII
 from segpy.packer import HeaderPacker
 
-from segpy.portability import seekable
 from segpy.trace_header import TraceHeaderRev1
 from segpy.util import file_length, filename_from_handle
 from segpy.datatypes import DATA_SAMPLE_FORMAT_TO_SEG_Y_TYPE, SEG_Y_TYPE_DESCRIPTION, SEG_Y_TYPE_TO_CTYPE, size_in_bytes
diff --git a/segpy/toolkit.py b/segpy/toolkit.py
index e1de337..d2dfd2b 100644
--- a/segpy/toolkit.py
+++ b/segpy/toolkit.py
@@ -1,16 +1,15 @@
 from __future__ import print_function
 
 from array import array
-from collections import namedtuple, OrderedDict
-import itertools
+from collections import OrderedDict
+from itertools import zip_longest, count
+
 import os
 import struct
 import re
 import logging
 
 from segpy import textual_reel_header_definition
-
-
 from segpy.catalog import CatalogBuilder
 from segpy.datatypes import SEG_Y_TYPE_TO_CTYPE, size_in_bytes
 from segpy.encoding import guess_encoding, is_supported_encoding, UnsupportedEncodingError
@@ -20,7 +19,7 @@ from segpy.packer import HeaderPacker
 from segpy.revisions import canonicalize_revision
 from segpy.trace_header import TraceHeaderRev1
 from segpy.util import file_length, batched, pad, complementary_intervals, NATIVE_ENDIANNESS
-from segpy.portability import EMPTY_BYTE_STRING, izip_longest
+from segpy.portability import EMPTY_BYTE_STRING
 
 HEADER_NEWLINE = '\r\n'
 
@@ -351,7 +350,7 @@ def catalog_traces(fh, bps, trace_header_format=TraceHeaderRev1, endian='>', pro
     alt_line_catalog_builder = CatalogBuilder()
     cdp_catalog_builder = CatalogBuilder()
 
-    for trace_number in itertools.count():
+    for trace_number in count():
         progress_callback(_READ_PROPORTION * pos_begin / length)
         fh.seek(pos_begin)
         data = fh.read(TRACE_HEADER_NUM_BYTES)
@@ -535,7 +534,7 @@ def format_standard_textual_header(revision, **kwargs):
     background_slices = complementary_intervals(placeholder_slices.values(), 0, len(template))
 
     chunks = []
-    for bg_slice, placeholder in izip_longest(background_slices, placeholder_slices.items()):
+    for bg_slice, placeholder in zip_longest(background_slices, placeholder_slices.items()):
 
         if bg_slice is not None:
             chunks.append(template[bg_slice])
diff --git a/segpy/util.py b/segpy/util.py
index 776aea2..52163bf 100644
--- a/segpy/util.py
+++ b/segpy/util.py
@@ -5,8 +5,6 @@ import sys
 
 from itertools import (islice, cycle, tee, chain, repeat)
 
-from segpy.portability import izip
-
 NATIVE_ENDIANNESS = '<' if sys.byteorder == 'little' else '>'
 
 UNSET = object()
@@ -25,7 +23,7 @@ def pairwise(iterable):
     """
     a, b = tee(iterable)
     next(b)
-    yield from izip(a, b)
+    yield from zip(a, b)
 
 
 def batched(iterable, batch_size, padding=UNSET):