BUG: missingdata: The ndmin parameter to np.array wasn't respecting NA masks

2 files changed, 31 insertions, 1 deletions

diff --git a/numpy/core/src/multiarray/multiarraymodule.c b/numpy/core/src/multiarray/multiarraymodule.c
index d23ecef83..003be5e39 100644
--- a/numpy/core/src/multiarray/multiarraymodule.c
+++ b/numpy/core/src/multiarray/multiarraymodule.c
@@ -1709,7 +1709,9 @@ _prepend_ones(PyArrayObject *arr, int nd, int ndmin)
     Py_INCREF(dtype);
     ret = (PyArrayObject *)PyArray_NewFromDescr(Py_TYPE(arr),
                         dtype, ndmin, newdims, newstrides,
-                        PyArray_DATA(arr), PyArray_FLAGS(arr), (PyObject *)arr);
+                        PyArray_DATA(arr),
+            PyArray_FLAGS(arr) & ~(NPY_ARRAY_MASKNA | NPY_ARRAY_OWNMASKNA),
+                        (PyObject *)arr);
     if (ret == NULL) {
         return NULL;
     }
@@ -1718,6 +1720,25 @@ _prepend_ones(PyArrayObject *arr, int nd, int ndmin)
         Py_DECREF(ret);
         return NULL;
     }
+
+    /* Take a view of the NA mask as well if necessary */
+    if (PyArray_HASMASKNA(arr)) {
+        PyArrayObject_fieldaccess *fret = (PyArrayObject_fieldaccess *)ret;
+
+        fret->maskna_dtype = PyArray_MASKNA_DTYPE(arr);
+        Py_INCREF(fret->maskna_dtype);
+        fret->maskna_data = PyArray_MASKNA_DATA(arr);
+
+        for (i = 0; i < num; ++i) {
+            fret->maskna_strides[i] = 0;
+        }
+        for (i = num; i < ndmin; ++i) {
+            fret->maskna_strides[i] = PyArray_MASKNA_STRIDES(arr)[i - num];
+        }
+        fret->flags |= NPY_ARRAY_MASKNA;
+    }
+
+
     return (PyObject *)ret;
 }
 
diff --git a/numpy/core/tests/test_maskna.py b/numpy/core/tests/test_maskna.py
index 8c0f9272a..0f63cc8bd 100644
--- a/numpy/core/tests/test_maskna.py
+++ b/numpy/core/tests/test_maskna.py
@@ -943,5 +943,14 @@ def test_array_maskna_concatenate():
     assert_equal(res[~np.isna(res)], [0,1,4,2,5,10])
     assert_equal(res.strides, (4, 16))
 
+def test_array_maskna_column_stack():
+    a = np.array((1,2,3), maskna=True)
+    b = np.array((2,3,4), maskna=True)
+    b[2] = np.NA
+    res = np.column_stack((a,b))
+    assert_equal(np.isna(res), [[0,0], [0,0], [0,1]])
+    assert_equal(res[~np.isna(res)], [1,2,2,3,3])
+
+
 if __name__ == "__main__":
     run_module_suite()