pyunlocbox as an optional dependency

pygsp/optimization.py

@@ -11,6 +11,16 @@
 logger = utils.build_logger(__name__)
 
 
+def _import_pyunlocbox():
+    try:
+        from pyunlocbox import functions, solvers
+    except Exception:
+        raise ImportError('Cannot import pyunlocbox, which is needed to solve '
+                          'this optimization problem. Try to install it with '
+                          'pip (or conda) install pyunlocbox.')
+    return functions, solvers
+
+
 def prox_tv(x, gamma, G, A=None, At=None, nu=1, tol=10e-4, maxit=200, use_matrix=True):
     r"""
     Total Variation proximal operator for graphs.
@@ -81,4 +91,5 @@ def l1_a(x):
         def l1_at(x):
             return G.div(x)
 
-    pyunlocbox.prox_l1(x, gamma, A=l1_a, At=l1_at, tight=tight, maxit=maxit, verbose=verbose, tol=tol)
+    functions, _ = _import_pyunlocbox()
+    functions.norm_l1(x, gamma, A=l1_a, At=l1_at, tight=tight, maxit=maxit, verbose=verbose, tol=tol)

setup.py

@@ -32,6 +32,8 @@
             # Approximate nearest neighbors for kNN graphs.
             'pyflann; python_version == "2.*"',
             'pyflann3; python_version == "3.*"',
+            # Convex optimization on graph.
+            'pyunlocbox',
             # Plot graphs, signals, and filters.
             'matplotlib',
             # Interactive graph visualization.
@@ -44,14 +46,12 @@
         ),
         # Testing dependencies.
         'test': [
-            'pyunlocbox',
             'flake8',
             'coverage',
             'coveralls',
         ],
         # Dependencies to build the documentation.
         'doc': [
-            'pyunlocbox',
             'sphinx',
             'numpydoc',
             'sphinxcontrib-bibtex',