make check_array raise in case of readonly memmap and copy=False

Perrine Letellier · Perrine Letellier · commit 0d4ef7ecd4c5 · 2015-10-21T12:14:30.000+02:00
diff --git a/sklearn/utils/estimator_checks.py b/sklearn/utils/estimator_checks.py
@@ -309,7 +309,7 @@ def _init_temp_memory(mmap_mode='r'):
         temp_folder = tempfile.mkdtemp(prefix='sklearn_checks_temp_')
         _TEMP_READONLY_MEMMAP_MEMORY = Memory(cachedir=temp_folder,
                                               mmap_mode=mmap_mode, verbose=0)
-        # Cannot use atexit as it is called everytime a test end,
+        # Cannot use atexit as it is called everytime a test ends,
         #  thus forcing us to regenerate cache at every check
         # atexit.register(_clear_temp_memory(warn=True))
 
diff --git a/sklearn/utils/validation.py b/sklearn/utils/validation.py
@@ -341,6 +341,9 @@ def check_array(array, accept_sparse=None, dtype="numeric", order=None,
     X_converted : object
         The converted and validated X.
     """
+    if isinstance(array, np.memmap) and array.mode == "r" and not copy:
+        raise ValueError('Can not modify inplace an array which is read-only')
+
     if isinstance(accept_sparse, str):
         accept_sparse = [accept_sparse]
 
