Don't require gzip or bz2 until the actual functionality is requested.

3 files changed, 32 insertions, 7 deletions

diff --git a/numpy/lib/_datasource.py b/numpy/lib/_datasource.py
index 06aae85d8..3fe1df615 100644
--- a/numpy/lib/_datasource.py
+++ b/numpy/lib/_datasource.py
@@ -34,17 +34,24 @@ Example:
 
 __docformat__ = "restructuredtext en"
 
-import bz2
-import gzip
 import os
 import tempfile
 from shutil import rmtree
 from urllib2 import urlopen, URLError
 from urlparse import urlparse
 
-
 # TODO: .zip support, .tar support?
-_file_openers = {".gz":gzip.open, ".bz2":bz2.BZ2File, None:file}
+_file_openers = {None: open}
+try:
+    import bz2
+    _file_openers[".bz2"] = bz2.BZ2File
+except ImportError:
+    pass
+try:
+    import gzip
+    _file_openers[".gz"] = gzip.open
+except ImportError:
+    pass
 
 
 def open(path, mode='r', destpath=os.curdir):
diff --git a/numpy/lib/io.py b/numpy/lib/io.py
index 6edf902e3..9e61ab2f8 100644
--- a/numpy/lib/io.py
+++ b/numpy/lib/io.py
@@ -8,7 +8,6 @@ __all__ = ['savetxt', 'loadtxt',
 
 import numpy as np
 import format
-import zipfile
 import cStringIO
 import tempfile
 import os
@@ -42,6 +41,9 @@ class NpzFile(object):
     with .files and the ZipFile object itself using .zip
     """
     def __init__(self, fid):
+        # Import is postponed to here since zipfile depends on gzip, an optional
+        # component of the so-called standard library.
+        import zipfile
         _zip = zipfile.ZipFile(fid)
         self._files = _zip.namelist()
         self.files = []
@@ -165,6 +167,10 @@ def savez(file, *args, **kwds):
     arr_0, arr_1, etc.
     """
 
+    # Import is postponed to here since zipfile depends on gzip, an optional
+    # component of the so-called standard library.
+    import zipfile
+
     if isinstance(file, str):
         if not file.endswith('.npz'):
             file = file + '.npz'
diff --git a/numpy/lib/tests/test__datasource.py b/numpy/lib/tests/test__datasource.py
index 89dd86687..f308cd1ad 100644
--- a/numpy/lib/tests/test__datasource.py
+++ b/numpy/lib/tests/test__datasource.py
@@ -1,6 +1,4 @@
 
-import bz2
-import gzip
 import os
 import sys
 import struct
@@ -90,6 +88,13 @@ class TestDataSourceOpen(NumpyTestCase):
         self.assertRaises(IOError, self.ds.open, invalid_file)
 
     def test_ValidGzipFile(self):
+        try:
+            import gzip
+        except ImportError:
+            # We don't have the bz2 capabilities to test.
+            # FIXME: when we start using nose, raise a SkipTest rather than
+            # passing the test.
+            return
         # Test datasource's internal file_opener for Gzip files.
         filepath = os.path.join(self.tmpdir, 'foobar.txt.gz')
         fp = gzip.open(filepath, 'w')
@@ -101,6 +106,13 @@ class TestDataSourceOpen(NumpyTestCase):
         self.assertEqual(magic_line, result)
 
     def test_ValidBz2File(self):
+        try:
+            import bz2
+        except ImportError:
+            # We don't have the bz2 capabilities to test.
+            # FIXME: when we start using nose, raise a SkipTest rather than
+            # passing the test.
+            return
         # Test datasource's internal file_opener for BZip2 files.
         filepath = os.path.join(self.tmpdir, 'foobar.txt.bz2')
         fp = bz2.BZ2File(filepath, 'w')