[MRG] correct independence of fgw barycenters to init (PythonOT#566)

* correct independence of fgw barycenters to init

* fix pep8 and tests

* correct PR id

* take into account comments

RELEASES.md

@@ -21,6 +21,7 @@
 - Fix line search evaluating cost outside of the interpolation range (Issue #502, PR #504)
 - Lazily instantiate backends to avoid unnecessary GPU memory pre-allocations on package import (Issue #516, PR #520)
 - Handle documentation and warnings when integers are provided to (f)gw solvers based on cg (Issue #530, PR #559)
+- Correct independence of `fgw_barycenters` to `init_C` and `init_X` (Issue #547, PR #566)
 
 ## 0.9.1
 *August 2023*

ot/gromov/_gw.py

@@ -166,10 +166,6 @@ def df(G):
         def df(G):
             return 0.5 * (gwggrad(constC, hC1, hC2, G, np_) + gwggrad(constCt, hC1t, hC2t, G, np_))
 
-    # removed since 0.9.2
-    #if loss_fun == 'kl_loss':
-    #    armijo = True # there is no closed form line-search with KL
-
     if armijo:
         def line_search(cost, G, deltaG, Mi, cost_G, **kwargs):
             return line_search_armijo(cost, G, deltaG, Mi, cost_G, nx=np_, **kwargs)
@@ -478,10 +474,6 @@ def df(G):
         def df(G):
             return 0.5 * (gwggrad(constC, hC1, hC2, G, np_) + gwggrad(constCt, hC1t, hC2t, G, np_))
 
-    # removed since 0.9.2
-    #if loss_fun == 'kl_loss':
-    #    armijo = True  # there is no closed form line-search with KL
-
     if armijo:
         def line_search(cost, G, deltaG, Mi, cost_G, **kwargs):
             return line_search_armijo(cost, G, deltaG, Mi, cost_G, nx=np_, **kwargs)
@@ -827,10 +819,6 @@ def gromov_barycenters(
     else:
         C = init_C
 
-    # removed since 0.9.2
-    #if loss_fun == 'kl_loss':
-    #    armijo = True
-
     cpt = 0
     err = 1
 
@@ -1005,16 +993,14 @@ def fgw_barycenters(
     else:
         if init_X is None:
             X = nx.zeros((N, d), type_as=ps[0])
+
         else:
             X = init_X
 
-    T = [nx.outer(p, q) for q in ps]
-
     Ms = [dist(X, Ys[s]) for s in range(len(Ys))]
 
-    # removed since 0.9.2
-    #if loss_fun == 'kl_loss':
-    #    armijo = True
+    if warmstartT:
+        T = [nx.outer(p, q) for q in ps]
 
     cpt = 0
     err_feature = 1
@@ -1030,11 +1016,19 @@ def fgw_barycenters(
         Cprev = C
         Xprev = X
 
+        if warmstartT:
+            T = [fused_gromov_wasserstein(
+                Ms[s], C, Cs[s], p, ps[s], loss_fun=loss_fun, alpha=alpha, armijo=armijo, symmetric=symmetric,
+                G0=T[s], max_iter=max_iter, tol_rel=1e-5, tol_abs=0., verbose=verbose, **kwargs) for s in range(S)]
+        else:
+            T = [fused_gromov_wasserstein(
+                Ms[s], C, Cs[s], p, ps[s], loss_fun=loss_fun, alpha=alpha, armijo=armijo, symmetric=symmetric,
+                G0=None, max_iter=max_iter, tol_rel=1e-5, tol_abs=0., verbose=verbose, **kwargs) for s in range(S)]
+        # T is N,ns
         if not fixed_features:
             Ys_temp = [y.T for y in Ys]
             X = update_feature_matrix(lambdas, Ys_temp, T, p).T
-
-        Ms = [dist(X, Ys[s]) for s in range(len(Ys))]
+            Ms = [dist(X, Ys[s]) for s in range(len(Ys))]
 
         if not fixed_structure:
             T_temp = [t.T for t in T]
@@ -1044,15 +1038,6 @@ def fgw_barycenters(
             elif loss_fun == 'kl_loss':
                 C = update_kl_loss(p, lambdas, T_temp, Cs)
 
-        if warmstartT:
-            T = [fused_gromov_wasserstein(
-                Ms[s], C, Cs[s], p, ps[s], loss_fun=loss_fun, alpha=alpha, armijo=armijo, symmetric=symmetric,
-                G0=T[s], max_iter=max_iter, tol_rel=1e-5, tol_abs=0., verbose=verbose, **kwargs) for s in range(S)]
-        else:
-            T = [fused_gromov_wasserstein(
-                Ms[s], C, Cs[s], p, ps[s], loss_fun=loss_fun, alpha=alpha, armijo=armijo, symmetric=symmetric,
-                G0=None, max_iter=max_iter, tol_rel=1e-5, tol_abs=0., verbose=verbose, **kwargs) for s in range(S)]
-        # T is N,ns
         err_feature = nx.norm(X - nx.reshape(Xprev, (N, d)))
         err_structure = nx.norm(C - Cprev)
         if log:

test/test_gromov.py

@@ -1425,6 +1425,13 @@ def test_fgw_barycenter(nx):
     init_C /= init_C.max()
     init_Cb = nx.from_numpy(init_C)
 
+    with pytest.raises(ot.utils.UndefinedParameter):  # to raise warning when `fixed_structure=True`and `init_C=None`
+        Xb, Cb = ot.gromov.fgw_barycenters(
+            n_samples, [ysb, ytb], [C1b, C2b], ps=[p1b, p2b], lambdas=None,
+            alpha=0.5, fixed_structure=True, init_C=None, fixed_features=False,
+            p=None, loss_fun='square_loss', max_iter=100, tol=1e-3
+        )
+
     Xb, Cb = ot.gromov.fgw_barycenters(
         n_samples, [ysb, ytb], [C1b, C2b], ps=[p1b, p2b], lambdas=None,
         alpha=0.5, fixed_structure=True, init_C=init_Cb, fixed_features=False,
@@ -1437,12 +1444,20 @@ def test_fgw_barycenter(nx):
     init_X = rng.randn(n_samples, ys.shape[1])
     init_Xb = nx.from_numpy(init_X)
 
+    with pytest.raises(ot.utils.UndefinedParameter):  # to raise warning when `fixed_features=True`and `init_X=None`
+        Xb, Cb, logb = ot.gromov.fgw_barycenters(
+            n_samples, [ysb, ytb], [C1b, C2b], [p1b, p2b], [.5, .5], 0.5,
+            fixed_structure=False, fixed_features=True, init_X=None,
+            p=pb, loss_fun='square_loss', max_iter=100, tol=1e-3,
+            warmstartT=True, log=True, random_state=98765, verbose=True
+        )
     Xb, Cb, logb = ot.gromov.fgw_barycenters(
         n_samples, [ysb, ytb], [C1b, C2b], [p1b, p2b], [.5, .5], 0.5,
         fixed_structure=False, fixed_features=True, init_X=init_Xb,
         p=pb, loss_fun='square_loss', max_iter=100, tol=1e-3,
         warmstartT=True, log=True, random_state=98765, verbose=True
     )
+
     X, C = nx.to_numpy(Xb), nx.to_numpy(Cb)
     np.testing.assert_allclose(C.shape, (n_samples, n_samples))
     np.testing.assert_allclose(X.shape, (n_samples, ys.shape[1]))