Handle sliced probes

Closes #205 and #206.

nengo_loihi/builder/probe.py

@@ -75,10 +75,15 @@ def conn_probe(model, nengo_probe):
     model.seeded[conn] = model.seeded[nengo_probe]
     model.seeds[conn] = model.seeds[nengo_probe]
 
+    if isinstance(nengo_probe.target, ObjView):
+        target_obj = nengo_probe.target.obj
+    else:
+        target_obj = nengo_probe.target
+
     d = conn.size_out
-    if isinstance(nengo_probe.target, Ensemble):
+    if isinstance(target_obj, Ensemble):
         # probed values are scaled by the target ensemble's radius
-        scale = nengo_probe.target.radius
+        scale = target_obj.radius
         w = np.diag(scale * np.ones(d))
         weights = np.vstack([w, -w])
     else:

nengo_loihi/tests/test_simulator.py

@@ -781,6 +781,47 @@ def test_simulator_passthrough(remove_passthrough, Simulator):
         assert conn_y_d not in model.params
 
 
+def test_slicing_bugs(Simulator, seed):
+
+    n = 50
+    with nengo.Network() as model:
+        a = nengo.Ensemble(n, 1, label="a")
+        p0 = nengo.Probe(a[0])
+        p = nengo.Probe(a)
+
+    with Simulator(model) as sim:
+        sim.run(0.1)
+
+    assert np.allclose(sim.data[p0], sim.data[p])
+    assert a in sim.model.params
+    assert a not in sim.model.host.params
+
+    with nengo.Network() as model:
+        nengo_loihi.add_params(model)
+
+        a = nengo.Ensemble(n, 1, label="a")
+
+        b0 = nengo.Ensemble(n, 1, label="b0", seed=seed)
+        model.config[b0].on_chip = False
+        nengo.Connection(a[0], b0)
+
+        b = nengo.Ensemble(n, 1, label="b", seed=seed)
+        model.config[b].on_chip = False
+        nengo.Connection(a, b)
+
+        p0 = nengo.Probe(b0)
+        p = nengo.Probe(b)
+
+    with Simulator(model) as sim:
+        sim.run(0.1)
+
+    assert np.allclose(sim.data[p0], sim.data[p])
+    assert a in sim.model.params
+    assert a not in sim.model.host.params
+    assert b not in sim.model.params
+    assert b in sim.model.host.params
+
+
 def test_network_unchanged(Simulator):
     with nengo.Network() as model:
         nengo.Ensemble(100, 1)

nengo_loihi/tests/test_splitter.py

@@ -263,6 +263,25 @@ def test_split_remove_passthrough(remove_passthrough):
         assert pd == (set(), set(), set())
 
 
+def test_sliced_passthrough_bug():
+    with nengo.Network() as model:
+        add_params(model)
+
+        a = nengo.Ensemble(1, 1, label="a")
+        passthrough = nengo.Node(size_in=1, label="passthrough")
+
+        nengo.Connection(a, passthrough)
+        p = nengo.Probe(passthrough[0])
+
+    splitter_directive = SplitterDirective(model, remove_passthrough=True)
+
+    assert splitter_directive.passthrough_directive == (set(), set(), set())
+
+    assert splitter_directive.on_chip(a)
+    assert not splitter_directive.on_chip(passthrough)
+    assert not splitter_directive.on_chip(p)
+
+
 def test_precompute_remove_passthrough():
     with nengo.Network() as net:
         add_params(net)