NF - warning for nicom import closes gh-10; error for not mosaic closes gh-11

Author: matthew-brett

nibabel/nicom/__init__.py

@@ -19,3 +19,10 @@
    dwiparams
    structreader
 """
+import warnings
+
+warnings.warn('The DICOM readers are highly experimental, unstable,'
+              ' and only work for Siemens time-series at the moment\n'
+              'Please use with caution.  We would be grateful for your '
+              'help in improving them',
+              UserWarning, stacklevel=2)

nibabel/nicom/dicomreaders.py

@@ -40,7 +40,7 @@ def read_mosaic_dwi_dir(dicom_path, globber='*.dcm'):
 
 
 def read_mosaic_dir(dicom_path, globber='*.dcm', check_is_dwi=False):
-    ''' Read all Siemens DICOMs in directory, return arrays, params
+    ''' Read all Siemens mosaic DICOMs in directory, return arrays, params
 
     Parameters
     ----------
@@ -77,6 +77,11 @@ def read_mosaic_dir(dicom_path, globber='*.dcm', check_is_dwi=False):
         raise IOError('Found no files with "%s"' % full_globber)
     for fname in filenames:
         dcm_w = wrapper_from_file(fname)
+        # Because the routine sorts by filename, it only makes sense to use this
+        # order for mosaic images.  Slice by slice dicoms need more sensible
+        # sorting
+        if not dcm_w.is_mosaic:
+            raise DicomReadError('data does not appear to be in mosaic format')
         arrays.append(dcm_w.get_data()[...,None])
         q = dcm_w.q_vector
         if q is None:  # probably not diffusion