[MRG] Fix Bug binary_search_circle on GPU and Gradients (#457)

* W circle + SSW

* Tests + Example SSW_1

* Example Wasserstein Circle + Tests

* Wasserstein on the circle wrt Unif

* Example SSW unif

* pep8

* np.linalg.qr for numpy < 1.22 by batch + add python3.11 to tests

* np qr

* rm test python 3.11

* update names, tests, backend transpose

* Comment error batchs

* semidiscrete_wasserstein2_unif_circle example

* torch permute method instead of torch.permute for previous versions

* update comments and doc

* doc wasserstein circle model as [0,1[

* Added ot.utils.get_coordinate_circle to get coordinates on the circle in turn

* Bug cuda w_circle + gradient ssw

* Bug cuda w_circle + gradient ssw

* backend detach

* Add PR in Releases.md

---------

Co-authored-by: Rémi Flamary <remi.flamary@gmail.com>

6 files changed, 70 insertions, 7 deletions

diff --git a/RELEASES.md b/RELEASES.md
index 6e4188f..214cc2a 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -7,6 +7,7 @@
 #### Closed issues
 
 - Fix circleci-redirector action and codecov (PR #460)
+- Fix issues with cuda for ot.binary_search_circle and with gradients for ot.sliced_wasserstein_sphere (PR #457)
 
 ## 0.9.0
 
diff --git a/ot/backend.py b/ot/backend.py
index 0779243..74f8366 100644
--- a/ot/backend.py
+++ b/ot/backend.py
@@ -951,6 +951,14 @@ class Backend():
         """
         raise NotImplementedError()
 
+    def detach(self, *args):
+        r"""
+        Detach tensors in arguments from the current graph.
+
+        See: https://pytorch.org/docs/stable/generated/torch.Tensor.detach.html
+        """
+        raise NotImplementedError()
+
 
 class NumpyBackend(Backend):
     """
@@ -1279,6 +1287,11 @@ class NumpyBackend(Backend):
     def transpose(self, a, axes=None):
         return np.transpose(a, axes)
 
+    def detach(self, *args):
+        if len(args) == 1:
+            return args[0]
+        return args
+
 
 class JaxBackend(Backend):
     """
@@ -1626,6 +1639,11 @@ class JaxBackend(Backend):
     def transpose(self, a, axes=None):
         return jnp.transpose(a, axes)
 
+    def detach(self, *args):
+        if len(args) == 1:
+            return jax.lax.stop_gradient((args[0],))[0]
+        return [jax.lax.stop_gradient((a,))[0] for a in args]
+
 
 class TorchBackend(Backend):
     """
@@ -2072,6 +2090,11 @@ class TorchBackend(Backend):
             axes = tuple(range(a.ndim)[::-1])
         return a.permute(axes)
 
+    def detach(self, *args):
+        if len(args) == 1:
+            return args[0].detach()
+        return [a.detach() for a in args]
+
 
 class CupyBackend(Backend):  # pragma: no cover
     """
@@ -2443,6 +2466,11 @@ class CupyBackend(Backend):  # pragma: no cover
     def transpose(self, a, axes=None):
         return cp.transpose(a, axes)
 
+    def detach(self, *args):
+        if len(args) == 1:
+            return args[0]
+        return args
+
 
 class TensorflowBackend(Backend):
 
@@ -2826,3 +2854,8 @@ class TensorflowBackend(Backend):
 
     def transpose(self, a, axes=None):
         return tf.transpose(a, perm=axes)
+
+    def detach(self, *args):
+        if len(args) == 1:
+            return tf.stop_gradient(args[0])
+        return [tf.stop_gradient(a) for a in args]
diff --git a/ot/lp/solver_1d.py b/ot/lp/solver_1d.py
index bcfc920..840801a 100644
--- a/ot/lp/solver_1d.py
+++ b/ot/lp/solver_1d.py
@@ -401,7 +401,7 @@ def roll_cols(M, shifts):
 
     n_rows, n_cols = M.shape
 
-    arange1 = nx.tile(nx.reshape(nx.arange(n_cols), (1, n_cols)), (n_rows, 1))
+    arange1 = nx.tile(nx.reshape(nx.arange(n_cols, type_as=shifts), (1, n_cols)), (n_rows, 1))
     arange2 = (arange1 - shifts) % n_cols
 
     return nx.take_along_axis(M, arange2, 1)
@@ -600,7 +600,7 @@ def binary_search_circle(u_values, v_values, u_weights=None, v_weights=None, p=1
 
     using e.g. ot.utils.get_coordinate_circle(x)
 
-    The function runs on backend but tensorflow is not supported.
+    The function runs on backend but tensorflow and jax are not supported.
 
     Parameters
     ----------
@@ -730,7 +730,7 @@ def binary_search_circle(u_values, v_values, u_weights=None, v_weights=None, p=1
             tp[((1 - mask) * (dCp >= 0)) > 0] = tc[((1 - mask) * (dCp >= 0)) > 0]
             tc[((1 - mask) * (1 - done)) > 0] = (tm[((1 - mask) * (1 - done)) > 0] + tp[((1 - mask) * (1 - done)) > 0]) / 2
 
-    w = ot_cost_on_circle(tc, u_values, v_values, u_cdf, v_cdf, p)
+    w = ot_cost_on_circle(nx.detach(tc), u_values, v_values, u_cdf, v_cdf, p)
 
     if log:
         return w, {"optimal_theta": tc[:, 0]}
@@ -743,7 +743,7 @@ def wasserstein1_circle(u_values, v_values, u_weights=None, v_weights=None, requ
     takes the value modulo 1.
     If the values are on :math:`S^1\subset\mathbb{R}^2`, first find the coordinates
     using e.g. the atan2 function.
-    The function runs on backend but tensorflow is not supported.
+    The function runs on backend but tensorflow and jax are not supported.
 
     .. math::
         W_1(u,v) = \int_0^1 |F_u(t)-F_v(t)-LevMed(F_u-F_v)|\ \mathrm{d}t
@@ -864,7 +864,7 @@ def wasserstein_circle(u_values, v_values, u_weights=None, v_weights=None, p=1,
 
     using e.g. ot.utils.get_coordinate_circle(x)
 
-    The function runs on backend but tensorflow is not supported.
+    The function runs on backend but tensorflow and jax are not supported.
 
     Parameters
     ----------
diff --git a/ot/sliced.py b/ot/sliced.py
index 077ff0b..fa2141e 100644
--- a/ot/sliced.py
+++ b/ot/sliced.py
@@ -271,7 +271,7 @@ def sliced_wasserstein_sphere(X_s, X_t, a=None, b=None, n_projections=50,
 
     - :math:`P^U_\# \mu` stands for the pushforwards of the projection :math:`\forall x\in S^{d-1},\ P^U(x) = \frac{U^Tx}{\|U^Tx\|_2}`
 
-    The function runs on backend but tensorflow is not supported.
+    The function runs on backend but tensorflow and jax are not supported.
 
     Parameters
     ----------
diff --git a/test/test_backend.py b/test/test_backend.py
index fd9a761..5351e52 100644
--- a/test/test_backend.py
+++ b/test/test_backend.py
@@ -296,6 +296,8 @@ def test_empty_backend():
         nx.atan2(v, v)
     with pytest.raises(NotImplementedError):
         nx.transpose(M)
+    with pytest.raises(NotImplementedError):
+        nx.detach(M)
 
 
 def test_func_backends(nx):
@@ -649,6 +651,16 @@ def test_func_backends(nx):
         lst_b.append(nx.to_numpy(A))
         lst_name.append("transpose")
 
+        A = nx.detach(Mb)
+        lst_b.append(nx.to_numpy(A))
+        lst_name.append("detach")
+
+        A, B = nx.detach(Mb, Mb)
+        lst_b.append(nx.to_numpy(A))
+        lst_name.append("detach A")
+        lst_b.append(nx.to_numpy(B))
+        lst_name.append("detach B")
+
         assert not nx.array_equal(Mb, vb), "array_equal (shape)"
         assert nx.array_equal(Mb, Mb), "array_equal (elements) - expected true"
         assert not nx.array_equal(
diff --git a/test/test_sliced.py b/test/test_sliced.py
index f54c799..7b7437a 100644
--- a/test/test_sliced.py
+++ b/test/test_sliced.py
@@ -10,7 +10,7 @@ import pytest
 
 import ot
 from ot.sliced import get_random_projections
-from ot.backend import tf
+from ot.backend import tf, torch
 
 
 def test_get_random_projections():
@@ -408,6 +408,23 @@ def test_sliced_sphere_backend_type_devices(nx):
         nx.assert_same_dtype_device(xb, valb)
 
 
+def test_sliced_sphere_gradient():
+    if torch:
+        import torch.nn.functional as F
+
+        X0 = torch.randn((500, 3))
+        X0 = F.normalize(X0, p=2, dim=-1)
+        X0.requires_grad_(True)
+
+        X1 = torch.randn((500, 3))
+        X1 = F.normalize(X1, p=2, dim=-1)
+
+        sw = ot.sliced_wasserstein_sphere(X1, X0, n_projections=500, p=2)
+        grad_x0 = torch.autograd.grad(sw, X0)[0]
+
+        assert not torch.any(torch.isnan(grad_x0))
+
+
 def test_sliced_sphere_unif_values_on_the_sphere():
     n = 100
     rng = np.random.RandomState(0)