[MAINT] Cleanup python2 sys.version checks

6 files changed, 36 insertions, 158 deletions

diff --git a/numpy/lib/_datasource.py b/numpy/lib/_datasource.py
index aa793958e..139b8c0ca 100644
--- a/numpy/lib/_datasource.py
+++ b/numpy/lib/_datasource.py
@@ -70,70 +70,6 @@ def _check_mode(mode, encoding, newline):
             raise ValueError("Argument 'newline' not supported in binary mode")
 
 
-def _python2_bz2open(fn, mode, encoding, newline):
-    """Wrapper to open bz2 in text mode.
-
-    Parameters
-    ----------
-    fn : str
-        File name
-    mode : {'r', 'w'}
-        File mode. Note that bz2 Text files are not supported.
-    encoding : str
-        Ignored, text bz2 files not supported in Python2.
-    newline : str
-        Ignored, text bz2 files not supported in Python2.
-    """
-    import bz2
-
-    _check_mode(mode, encoding, newline)
-
-    if "t" in mode:
-        # BZ2File is missing necessary functions for TextIOWrapper
-        warnings.warn("Assuming latin1 encoding for bz2 text file in Python2",
-                      RuntimeWarning, stacklevel=5)
-        mode = mode.replace("t", "")
-    return bz2.BZ2File(fn, mode)
-
-def _python2_gzipopen(fn, mode, encoding, newline):
-    """ Wrapper to open gzip in text mode.
-
-    Parameters
-    ----------
-    fn : str, bytes, file
-        File path or opened file.
-    mode : str
-        File mode. The actual files are opened as binary, but will decoded
-        using the specified `encoding` and `newline`.
-    encoding : str
-        Encoding to be used when reading/writing as text.
-    newline : str
-        Newline to be used when reading/writing as text.
-
-    """
-    import gzip
-    # gzip is lacking read1 needed for TextIOWrapper
-    class GzipWrap(gzip.GzipFile):
-        def read1(self, n):
-            return self.read(n)
-
-    _check_mode(mode, encoding, newline)
-
-    gz_mode = mode.replace("t", "")
-
-    if isinstance(fn, (str, bytes)):
-        binary_file = GzipWrap(fn, gz_mode)
-    elif hasattr(fn, "read") or hasattr(fn, "write"):
-        binary_file = GzipWrap(None, gz_mode, fileobj=fn)
-    else:
-        raise TypeError("filename must be a str or bytes object, or a file")
-
-    if "t" in mode:
-        return io.TextIOWrapper(binary_file, encoding, newline=newline)
-    else:
-        return binary_file
-
-
 # Using a class instead of a module-level dictionary
 # to reduce the initial 'import numpy' overhead by
 # deferring the import of lzma, bz2 and gzip until needed
@@ -174,19 +110,13 @@ class _FileOpeners:
 
         try:
             import bz2
-            if sys.version_info[0] >= 3:
-                self._file_openers[".bz2"] = bz2.open
-            else:
-                self._file_openers[".bz2"] = _python2_bz2open
+            self._file_openers[".bz2"] = bz2.open
         except ImportError:
             pass
 
         try:
             import gzip
-            if sys.version_info[0] >= 3:
-                self._file_openers[".gz"] = gzip.open
-            else:
-                self._file_openers[".gz"] = _python2_gzipopen
+            self._file_openers[".gz"] = gzip.open
         except ImportError:
             pass
 
@@ -547,14 +477,10 @@ class DataSource:
         if os.path.exists(path):
             return True
 
-        # We import this here because importing urllib2 is slow and
+        # We import this here because importing urllib is slow and
         # a significant fraction of numpy's total import time.
-        if sys.version_info[0] >= 3:
-            from urllib.request import urlopen
-            from urllib.error import URLError
-        else:
-            from urllib2 import urlopen
-            from urllib2 import URLError
+        from urllib.request import urlopen
+        from urllib.error import URLError
 
         # Test cached url
         upath = self.abspath(path)
diff --git a/numpy/lib/format.py b/numpy/lib/format.py
index 15a74518b..114bae287 100644
--- a/numpy/lib/format.py
+++ b/numpy/lib/format.py
@@ -162,7 +162,6 @@ evolved with time and this document is more current.
 
 """
 import numpy
-import sys
 import io
 import warnings
 from numpy.lib.utils import safe_eval
@@ -213,10 +212,7 @@ def magic(major, minor):
         raise ValueError("major version must be 0 <= major < 256")
     if minor < 0 or minor > 255:
         raise ValueError("minor version must be 0 <= minor < 256")
-    if sys.version_info[0] < 3:
-        return MAGIC_PREFIX + chr(major) + chr(minor)
-    else:
-        return MAGIC_PREFIX + bytes([major, minor])
+    return MAGIC_PREFIX + bytes([major, minor])
 
 def read_magic(fp):
     """ Read the magic string to get the version of the file format.
@@ -234,10 +230,7 @@ def read_magic(fp):
     if magic_str[:-2] != MAGIC_PREFIX:
         msg = "the magic string is not correct; expected %r, got %r"
         raise ValueError(msg % (MAGIC_PREFIX, magic_str[:-2]))
-    if sys.version_info[0] < 3:
-        major, minor = map(ord, magic_str[-2:])
-    else:
-        major, minor = magic_str[-2:]
+    major, minor = magic_str[-2:]
     return major, minor
 
 def _has_metadata(dt):
@@ -542,10 +535,7 @@ def _filter_header(s):
 
     """
     import tokenize
-    if sys.version_info[0] >= 3:
-        from io import StringIO
-    else:
-        from StringIO import StringIO
+    from io import StringIO
 
     tokens = []
     last_token_was_number = False
@@ -738,12 +728,10 @@ def read_array(fp, allow_pickle=False, pickle_kwargs=None):
         try:
             array = pickle.load(fp, **pickle_kwargs)
         except UnicodeError as err:
-            if sys.version_info[0] >= 3:
-                # Friendlier error message
-                raise UnicodeError("Unpickling a python object failed: %r\n"
-                                   "You may need to pass the encoding= option "
-                                   "to numpy.load" % (err,))
-            raise
+            # Friendlier error message
+            raise UnicodeError("Unpickling a python object failed: %r\n"
+                               "You may need to pass the encoding= option "
+                               "to numpy.load" % (err,))
     else:
         if isfileobj(fp):
             # We can use the fast fromfile() function.
diff --git a/numpy/lib/mixins.py b/numpy/lib/mixins.py
index d4811b94d..50157069c 100644
--- a/numpy/lib/mixins.py
+++ b/numpy/lib/mixins.py
@@ -1,6 +1,4 @@
 """Mixin classes for custom array types that don't inherit from ndarray."""
-import sys
-
 from numpy.core import umath as um
 
 
@@ -152,9 +150,7 @@ class NDArrayOperatorsMixin:
     __mul__, __rmul__, __imul__ = _numeric_methods(um.multiply, 'mul')
     __matmul__, __rmatmul__, __imatmul__ = _numeric_methods(
         um.matmul, 'matmul')
-    if sys.version_info.major < 3:
-        # Python 3 uses only __truediv__ and __floordiv__
-        __div__, __rdiv__, __idiv__ = _numeric_methods(um.divide, 'div')
+    # Python 3 does not use __div__, __rdiv__, or __idiv__
     __truediv__, __rtruediv__, __itruediv__ = _numeric_methods(
         um.true_divide, 'truediv')
     __floordiv__, __rfloordiv__, __ifloordiv__ = _numeric_methods(
diff --git a/numpy/lib/npyio.py b/numpy/lib/npyio.py
index c47e388c0..29af488d2 100644
--- a/numpy/lib/npyio.py
+++ b/numpy/lib/npyio.py
@@ -7,6 +7,7 @@ import warnings
 import weakref
 import contextlib
 from operator import itemgetter, index as opindex
+from collections.abc import Mapping
 
 import numpy as np
 from . import format
@@ -26,12 +27,6 @@ from numpy.compat import (
     pickle, contextlib_nullcontext
     )
 
-if sys.version_info[0] >= 3:
-    from collections.abc import Mapping
-else:
-    from future_builtins import map
-    from collections import Mapping
-
 
 @set_module('numpy')
 def loads(*args, **kwargs):
@@ -264,26 +259,25 @@ class NpzFile(Mapping):
             raise KeyError("%s is not a file in the archive" % key)
 
 
-    if sys.version_info.major == 3:
-        # deprecate the python 2 dict apis that we supported by accident in
-        # python 3. We forgot to implement itervalues() at all in earlier
-        # versions of numpy, so no need to deprecated it here.
+    # deprecate the python 2 dict apis that we supported by accident in
+    # python 3. We forgot to implement itervalues() at all in earlier
+    # versions of numpy, so no need to deprecated it here.
 
-        def iteritems(self):
-            # Numpy 1.15, 2018-02-20
-            warnings.warn(
-                "NpzFile.iteritems is deprecated in python 3, to match the "
-                "removal of dict.itertems. Use .items() instead.",
-                DeprecationWarning, stacklevel=2)
-            return self.items()
+    def iteritems(self):
+        # Numpy 1.15, 2018-02-20
+        warnings.warn(
+            "NpzFile.iteritems is deprecated in python 3, to match the "
+            "removal of dict.itertems. Use .items() instead.",
+            DeprecationWarning, stacklevel=2)
+        return self.items()
 
-        def iterkeys(self):
-            # Numpy 1.15, 2018-02-20
-            warnings.warn(
-                "NpzFile.iterkeys is deprecated in python 3, to match the "
-                "removal of dict.iterkeys. Use .keys() instead.",
-                DeprecationWarning, stacklevel=2)
-            return self.keys()
+    def iterkeys(self):
+        # Numpy 1.15, 2018-02-20
+        warnings.warn(
+            "NpzFile.iterkeys is deprecated in python 3, to match the "
+            "removal of dict.iterkeys. Use .keys() instead.",
+            DeprecationWarning, stacklevel=2)
+        return self.keys()
 
 
 @set_module('numpy')
@@ -412,11 +406,7 @@ def load(file, mmap_mode=None, allow_pickle=False, fix_imports=True,
         # result can similarly silently corrupt numerical data.
         raise ValueError("encoding must be 'ASCII', 'latin1', or 'bytes'")
 
-    if sys.version_info[0] >= 3:
-        pickle_kwargs = dict(encoding=encoding, fix_imports=fix_imports)
-    else:
-        # Nothing to do on Python 2
-        pickle_kwargs = {}
+    pickle_kwargs = dict(encoding=encoding, fix_imports=fix_imports)
 
     # TODO: Use contextlib.ExitStack once we drop Python 2
     if hasattr(file, 'read'):
@@ -539,16 +529,10 @@ def save(file, arr, allow_pickle=True, fix_imports=True):
         fid = open(file, "wb")
         own_fid = True
 
-    if sys.version_info[0] >= 3:
-        pickle_kwargs = dict(fix_imports=fix_imports)
-    else:
-        # Nothing to do on Python 2
-        pickle_kwargs = None
-
     try:
         arr = np.asanyarray(arr)
         format.write_array(fid, arr, allow_pickle=allow_pickle,
-                           pickle_kwargs=pickle_kwargs)
+                           pickle_kwargs=dict(fix_imports=fix_imports))
     finally:
         if own_fid:
             fid.close()
@@ -691,7 +675,7 @@ def savez_compressed(file, *args, **kwds):
     The ``.npz`` file format is a zipped archive of files named after the
     variables they contain.  The archive is compressed with
     ``zipfile.ZIP_DEFLATED`` and each file in the archive contains one variable
-    in ``.npy`` format. For a description of the ``.npy`` format, see 
+    in ``.npy`` format. For a description of the ``.npy`` format, see
     :py:mod:`numpy.lib.format`.
 
 
@@ -1375,9 +1359,6 @@ def savetxt(fname, X, fmt='%.18e', delimiter=' ', newline='\n', header='',
         open(fname, 'wt').close()
         fh = np.lib._datasource.open(fname, 'wt', encoding=encoding)
         own_fh = True
-        # need to convert str to unicode for text io output
-        if sys.version_info[0] == 2:
-            fh = WriteWrap(fh, encoding or 'latin1')
     elif hasattr(fname, 'write'):
         # wrap to handle byte output streams
         fh = WriteWrap(fname, encoding or 'latin1')
diff --git a/numpy/lib/recfunctions.py b/numpy/lib/recfunctions.py
index 4e62169f4..af4cfa09d 100644
--- a/numpy/lib/recfunctions.py
+++ b/numpy/lib/recfunctions.py
@@ -5,7 +5,6 @@ Most of these functions were initially implemented by John Hunter for
 matplotlib.  They have been rewritten and extended for convenience.
 
 """
-import sys
 import itertools
 import numpy as np
 import numpy.ma as ma
@@ -17,9 +16,6 @@ from numpy.lib._iotools import _is_string_like
 from numpy.compat import basestring
 from numpy.testing import suppress_warnings
 
-if sys.version_info[0] < 3:
-    from future_builtins import zip
-
 _check_fill_value = np.ma.core._check_fill_value
 
 
@@ -333,12 +329,7 @@ def _izip_records(seqarrays, fill_value=None, flatten=True):
     else:
         zipfunc = _izip_fields
 
-    if sys.version_info[0] >= 3:
-        zip_longest = itertools.zip_longest
-    else:
-        zip_longest = itertools.izip_longest
-
-    for tup in zip_longest(*seqarrays, fillvalue=fill_value):
+    for tup in itertools.zip_longest(*seqarrays, fillvalue=fill_value):
         yield tuple(zipfunc(tup))
 
 
diff --git a/numpy/lib/utils.py b/numpy/lib/utils.py
index d41a6e541..152322115 100644
--- a/numpy/lib/utils.py
+++ b/numpy/lib/utils.py
@@ -871,11 +871,7 @@ def _lookfor_generate_cache(module, import_modules, regenerate):
     # Local import to speed up numpy's import time.
     import inspect
 
-    if sys.version_info[0] >= 3:
-        # In Python3 stderr, stdout are text files.
-        from io import StringIO
-    else:
-        from StringIO import StringIO
+    from io import StringIO
 
     if module is None:
         module = "numpy"