def test_axis(self):
# Vector norms.
# Compare the use of `axis` with computing the norm of each row
# or column separately.
A = array([[1, 2, 3], [4, 5, 6]], dtype=self.dt)
for order in [None, -1, 0, 1, 2, 3, np.Inf, -np.Inf]:
expected0 = [norm(A[:, k], ord=order) for k in range(A.shape[1])]
assert_almost_equal(norm(A, ord=order, axis=0), expected0)
expected1 = [norm(A[k, :], ord=order) for k in range(A.shape[0])]
assert_almost_equal(norm(A, ord=order, axis=1), expected1)
# Matrix norms.
B = np.arange(1, 25, dtype=self.dt).reshape(2, 3, 4)
nd = B.ndim
for order in [None, -2, 2, -1, 1, np.Inf, -np.Inf, 'fro']:
for axis in itertools.combinations(range(-nd, nd), 2):
row_axis, col_axis = axis
if row_axis < 0:
row_axis += nd
if col_axis < 0:
col_axis += nd
if row_axis == col_axis:
assert_raises(ValueError, norm, B, ord=order, axis=axis)
else:
n = norm(B, ord=order, axis=axis)
# The logic using k_index only works for nd = 3.
# This has to be changed if nd is increased.
k_index = nd - (row_axis + col_axis)
if row_axis < col_axis:
expected = [norm(B[:].take(k, axis=k_index), ord=order)
for k in range(B.shape[k_index])]
else:
expected = [norm(B[:].take(k, axis=k_index).T, ord=order)
for k in range(B.shape[k_index])]
assert_almost_equal(n, expected)
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