Wrap v and mat arrays in ReadonlyWrapper to support readonly

jjerphan · ogrisel · jjerphan · commit 2646b1110358 · 2021-11-17T11:09:29.000+01:00
Co-authored-by: Olivier Grisel &lt;olivier.grisel@ensta.org&gt;
diff --git a/sklearn/metrics/_dist_metrics.pyx b/sklearn/metrics/_dist_metrics.pyx
@@ -29,7 +29,7 @@ cdef DTYPE_t INF = np.inf
 
 from ..utils._typedefs cimport DTYPE_t, ITYPE_t, DITYPE_t, DTYPECODE
 from ..utils._typedefs import DTYPE, ITYPE
-
+from ..utils._readonly_array_wrapper import ReadonlyArrayWrapper
 
 ######################################################################
 # newObj function
@@ -191,8 +191,8 @@ cdef class DistanceMetric:
     """
     def __cinit__(self):
         self.p = 2
-        self.vec = np.zeros(1, dtype=DTYPE, order='c')
-        self.mat = np.zeros((1, 1), dtype=DTYPE, order='c')
+        self.vec = ReadonlyArrayWrapper(np.zeros(1, dtype=DTYPE, order='c'))
+        self.mat = ReadonlyArrayWrapper(np.zeros((1, 1), dtype=DTYPE, order='c'))
         self.size = 1
 
     def __reduce__(self):
@@ -214,8 +214,8 @@ cdef class DistanceMetric:
         set state for pickling
         """
         self.p = state[0]
-        self.vec = state[1]
-        self.mat = state[2]
+        self.vec = ReadonlyArrayWrapper(state[1])
+        self.mat = ReadonlyArrayWrapper(state[2])
         if self.__class__.__name__ == "PyFuncDistance":
             self.func = state[3]
             self.kwargs = state[4]
@@ -444,7 +444,7 @@ cdef class SEuclideanDistance(DistanceMetric):
        D(x, y) = \sqrt{ \sum_i \frac{ (x_i - y_i) ^ 2}{V_i} }
     """
     def __init__(self, V):
-        self.vec = np.asarray(V, dtype=DTYPE)
+        self.vec = ReadonlyArrayWrapper(np.asarray(V, dtype=DTYPE))
         self.size = self.vec.shape[0]
         self.p = 2
 
