diff options
Diffstat (limited to 'numpy')
| -rw-r--r-- | numpy/core/src/multiarray/shape.c | 31 | ||||
| -rw-r--r-- | numpy/core/tests/test_regression.py | 9 |
2 files changed, 37 insertions, 3 deletions
diff --git a/numpy/core/src/multiarray/shape.c b/numpy/core/src/multiarray/shape.c index 97ddb2e61..4223e49f6 100644 --- a/numpy/core/src/multiarray/shape.c +++ b/numpy/core/src/multiarray/shape.c @@ -355,10 +355,14 @@ _attempt_nocopy_reshape(PyArrayObject *self, int newnd, npy_intp* newdims, int oldnd; npy_intp olddims[NPY_MAXDIMS]; npy_intp oldstrides[NPY_MAXDIMS]; - npy_intp np, op; + npy_intp np, op, last_stride; int oi, oj, ok, ni, nj, nk; oldnd = 0; + /* + * Remove axes with dimension 1 from the old array. They have no effect + * but would need special cases since their strides do not matter. + */ for (oi = 0; oi < PyArray_NDIM(self); oi++) { if (PyArray_DIMS(self)[oi]!= 1) { olddims[oldnd] = PyArray_DIMS(self)[oi]; @@ -390,27 +394,31 @@ _attempt_nocopy_reshape(PyArrayObject *self, int newnd, npy_intp* newdims, /* different total sizes; no hope */ return 0; } - /* the current code does not handle 0-sized arrays, so give up */ + if (np == 0) { + /* the current code does not handle 0-sized arrays, so give up */ return 0; } + /* oi to oj and ni to nj give the axis ranges currently worked with */ oi = 0; oj = 1; ni = 0; nj = 1; - while(ni < newnd && oi < oldnd) { + while (ni < newnd && oi < oldnd) { np = newdims[ni]; op = olddims[oi]; while (np != op) { if (np < op) { + /* Misses trailing 1s, these are handled later */ np *= newdims[nj++]; } else { op *= olddims[oj++]; } } + /* Check whether the original axes can be combined */ for (ok = oi; ok < oj - 1; ok++) { if (is_f_order) { if (oldstrides[ok+1] != olddims[ok]*oldstrides[ok]) { @@ -427,6 +435,7 @@ _attempt_nocopy_reshape(PyArrayObject *self, int newnd, npy_intp* newdims, } } + /* Calculate new strides for all axes currently worked with */ if (is_f_order) { newstrides[ni] = oldstrides[oi]; for (nk = ni + 1; nk < nj; nk++) { @@ -445,6 +454,22 @@ _attempt_nocopy_reshape(PyArrayObject *self, int newnd, npy_intp* newdims, } /* + * Set strides corresponding to trailing 1s of the new shape. + */ + if (ni >= 1) { + last_stride = newstrides[ni - 1]; + } + else { + last_stride = PyArray_ITEMSIZE(self); + } + if (is_f_order) { + last_stride *= newdims[ni - 1]; + } + for (nk = ni; nk < newnd; nk++) { + newstrides[nk] = last_stride; + } + + /* fprintf(stderr, "success: _attempt_nocopy_reshape ("); for (oi=0; oi<oldnd; oi++) fprintf(stderr, "(%d,%d), ", olddims[oi], oldstrides[oi]); diff --git a/numpy/core/tests/test_regression.py b/numpy/core/tests/test_regression.py index 1cf2e6e85..1f71f480e 100644 --- a/numpy/core/tests/test_regression.py +++ b/numpy/core/tests/test_regression.py @@ -545,6 +545,15 @@ class TestRegression(TestCase): a = np.ones((0,2)) a.shape = (-1,2) + def test_reshape_trailing_ones_strides(self): + # Github issue gh-2949, bad strides for trailing ones of new shape + a = np.zeros(12, dtype=np.int32)[::2] # not contiguous + strides_c = (16, 8, 8, 8) + strides_f = (8, 24, 48, 48) + assert_equal(a.reshape(3, 2, 1, 1).strides, strides_c) + assert_equal(a.reshape(3, 2, 1, 1, order='F').strides, strides_f) + assert_equal(np.array(0, dtype=np.int32).reshape(1,1).strides, (4,4)) + def test_repeat_discont(self, level=rlevel): """Ticket #352""" a = np.arange(12).reshape(4,3)[:,2] |