Merge branch 'minor_fixups' into 'NIFTy_5'

Minor fixups

See merge request ift/nifty-dev!170

Dockerfile

@@ -5,7 +5,7 @@ RUN apt-get update && apt-get install -y \
     git \
     # Packages needed for NIFTy
     libfftw3-dev \
-    python3 python3-pip python3-dev python3-future python3-scipy cython3 \
+    python3 python3-pip python3-dev python3-scipy \
     # Documentation build dependencies
     python3-sphinx python3-sphinx-rtd-theme \
     # Testing dependencies

nifty5/operators/linear_interpolation.py

@@ -16,7 +16,7 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik.
 
 from functools import reduce
-from operator import mul
+from operator import add
 
 import numpy as np
 from scipy.sparse import coo_matrix
@@ -53,7 +53,7 @@ class LinearInterpolator(LinearOperator):
         dims = [len(dom.shape) for dom in self.domain]
 
         # FIXME This needs to be removed as soon as the bug below is fixed.
-        if not dims.count(dims[0]) == len(dims):
+        if dims.count(dims[0]) != len(dims):
             raise TypeError(
                 'This is a bug. Please extend LinearInterpolators functionality!'
             )
@@ -62,7 +62,7 @@ class LinearInterpolator(LinearOperator):
         if not (isinstance(sampling_points, np.ndarray) and len(shp) == 2):
             raise TypeError
         n_dim, n_points = shp
-        if not n_dim == reduce(mul, dims):
+        if n_dim != reduce(add, dims):
             raise TypeError
         self._target = makeDomain(UnstructuredDomain(n_points))
         self._capability = self.TIMES | self.ADJOINT_TIMES