NF - testing compressed reading of minc files

Author: matthew-brett

nibabel/externals/netcdf.py

@@ -286,11 +286,16 @@ def __setattr__(self, attr, value):
 
     def close(self):
         """Closes the NetCDF file."""
-        if not self.fp.closed:
-            try:
-                self.flush()
-            finally:
-                self.fp.close()
+        try:
+            is_closed = self.fp.closed
+        except AttributeError: # gzip files don't have closed attr
+            is_closed = False
+        if is_closed:
+            return
+        try:
+            self.flush()
+        finally:
+            self.fp.close()
     __del__ = close
 
     def createDimension(self, name, length):

nibabel/minc.py

@@ -191,6 +191,7 @@ class MincImage(SpatialImage):
     the MINC file on load.
     '''
     files_types = (('image', '.mnc'),)
+    _compressed_exts = ('.gz', '.bz2')
 
     class ImageArrayProxy(object):
         ''' Minc implemention of array proxy protocol
@@ -209,7 +210,6 @@ def __array__(self):
                 self._data = self.minc_file.get_scaled_data()
             return self._data
 
-
     @classmethod
     def from_file_map(klass, file_map):
         fobj = file_map['image'].get_prepare_fileobj()

nibabel/tests/test_minc.py

@@ -6,53 +6,73 @@
 #   copyright and license terms.
 #
 ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ##
+from __future__ import with_statement
+
 import os
+import gzip
+import bz2
 
 import numpy as np
 
 from ..externals.netcdf import netcdf_file as netcdf
 
 from .. import load, Nifti1Image
 from ..minc import MincFile
-from ..spatialimages import ImageFileError
+
 from nose.tools import (assert_true, assert_equal, assert_false, assert_raises)
 from numpy.testing import assert_array_equal, assert_array_almost_equal
+from ..tmpdirs import InTemporaryDirectory
 from ..testing import data_path
 
-mnc_fname = os.path.join(data_path, 'tiny.mnc')
-mnc_shape = (10,20,20)
-mnc_affine = np.array([[0, 0, 2.0, -20],
+MINC_EXAMPLE = dict(
+    fname = os.path.join(data_path, 'tiny.mnc'),
+    shape = (10,20,20),
+    affine = np.array([[0, 0, 2.0, -20],
                        [0, 2.0, 0, -20],
                        [2.0, 0, 0, -10],
-                       [0, 0, 0, 1]])
+                       [0, 0, 0, 1]]),
+    # These values from SPM2
+    min = 0.20784314,
+    max = 0.74901961,
+    mean = 0.60602819)
 
 
 def test_mincfile():
-    mnc = MincFile(netcdf(mnc_fname, 'r'))
+    mnc = MincFile(netcdf(MINC_EXAMPLE['fname'], 'r'))
     assert_equal(mnc.get_data_dtype().type, np.uint8)
-    assert_equal(mnc.get_data_shape(), mnc_shape)
+    assert_equal(mnc.get_data_shape(), MINC_EXAMPLE['shape'])
     assert_equal(mnc.get_zooms(), (2.0, 2.0, 2.0))
-    assert_array_equal(mnc.get_affine(), mnc_affine)
+    assert_array_equal(mnc.get_affine(), MINC_EXAMPLE['affine'])
     data = mnc.get_scaled_data()
-    assert_equal(data.shape, mnc_shape)
+    assert_equal(data.shape, MINC_EXAMPLE['shape'])
 
 
 def test_load():
     # Check highest level load of minc works
-    img = load(mnc_fname)
+    img = load(MINC_EXAMPLE['fname'])
     data = img.get_data()
-    assert_equal(data.shape, mnc_shape)
+    assert_equal(data.shape, MINC_EXAMPLE['shape'])
     # min, max, mean values from read in SPM2
     assert_array_almost_equal(data.min(), 0.20784314)
     assert_array_almost_equal(data.max(), 0.74901961)
-    np.testing.assert_array_almost_equal(data.mean(), 0.60602819)
+    assert_array_almost_equal(data.mean(), 0.60602819)
     # check if mnc can be converted to nifti
     ni_img = Nifti1Image.from_image(img)
-    assert_array_equal(ni_img.get_affine(), mnc_affine)
+    assert_array_equal(ni_img.get_affine(), MINC_EXAMPLE['affine'])
     assert_array_equal(ni_img.get_data(), data)
 
 
 def test_compressed():
-    # we can't read minc compreesed, raise error
-    assert_raises(ImageFileError, load, 'test.mnc.gz')
-    assert_raises(ImageFileError, load, 'test.mnc.bz2')
+    # we can read minc compressed
+    content = open(MINC_EXAMPLE['fname'], 'rb').read()
+    openers_exts = ((gzip.open, '.gz'), (bz2.BZ2File, '.bz2'))
+    with InTemporaryDirectory():
+        for opener, ext in openers_exts:
+            fname = 'test.mnc' + ext
+            fobj = opener(fname, 'wb')
+            fobj.write(content)
+            fobj.close()
+            img = load(fname)
+            data = img.get_data()
+            assert_array_almost_equal(data.mean(), 0.60602819)
+            del img