Initial adaptation of peak.util.imports

package/MDAnalysis/analysis/density.py

@@ -118,31 +118,7 @@
 import os.path
 import errno
 import warnings
-
-try:
-    from gridData import Grid
-except ImportError:
-    raise ImportError(
-        """ImportError: The GridDataFormats package can not be found!
-
-        The 'gridData' module from GridDataFormats could not be
-        imported. Please install it first.  You can try installing
-        directly from the internet:
-
-          pip install GridDataFormats
-
-        or
-
-          conda config --add channels conda-forge
-          conda install griddataformats
-
-        Alternatively, download the package from
-
-          http://pypi.python.org/pypi/GridDataFormats/
-
-        and install in the usual manner.
-        """
-    )
+from gridData import Grid
 
 import MDAnalysis
 from MDAnalysis.core import groups

package/MDAnalysis/analysis/distances.py

@@ -42,7 +42,6 @@
            'contact_matrix', 'dist', 'between']
 
 import numpy as np
-import scipy.sparse
 
 from MDAnalysis.lib.distances import distance_array, self_distance_array
 from MDAnalysis.lib.c_distances import contact_matrix_no_pbc, contact_matrix_pbc
@@ -52,6 +51,9 @@
 import logging
 logger = logging.getLogger("MDAnalysis.analysis.distances")
 
+# Optional and/or lazily imported modules
+from MDAnalysis.lib import lazy
+scipy = lazy.import_module('scipy.sparse', level='base')
 
 def contact_matrix(coord, cutoff=15.0, returntype="numpy", box=None):
     '''Calculates a matrix of contacts.