Fix bug with multiple indices in post ObjView

Also test that boolean indexing works. With this, advanced indexing
is fully supported for ObjViews in connections.

Fixes #947.

CHANGES.rst

@@ -47,6 +47,8 @@ Release History
   (`#1340 <https://github.com/nengo/nengo/pull/1340>`_)
 - Fixed an issue in which ``ShapeParam`` would always store ``None``.
   (`#1342 <https://github.com/nengo/nengo/pull/1342>`_)
+- Fixed an issue in which multiple identical indices in a slice were ignored.
+  (`#947 <https://github.com/nengo/nengo/issues/947>`_)
 
 **Deprecated**
 

nengo/base.py

@@ -152,7 +152,7 @@ def __init__(self, obj, key=slice(None)):
         # Node.size_in != size_out, so one of these can be invalid
         try:
             self.size_in = np.arange(self.obj.size_in)[key].size
-        except IndexError:
+        except (IndexError, ValueError):
             self.size_in = None
         try:
             self.size_out = np.arange(self.obj.size_out)[key].size

nengo/builder/operator.py

@@ -35,6 +35,7 @@
 import numpy as np
 
 import nengo.utils.numpy as npext
+from nengo.utils.compat import is_array_like
 from nengo.utils.connection import function_name
 from nengo.exceptions import BuildError, SimulationError
 
@@ -386,9 +387,21 @@ def make_step(self, signals, dt, rng):
         dst_slice = self.dst_slice if self.dst_slice is not None else Ellipsis
         inc = self.inc
 
-        if inc:
+        dst_slice = (np.asarray(dst_slice) if is_array_like(dst_slice) else
+                     dst_slice)
+        # There are repeated indices in dst_slice, special case
+        repeats = (is_array_like(dst_slice) and dst_slice.dtype != np.bool and
+                   len(np.unique(dst_slice)) < len(dst_slice))
+        if inc and repeats:
+            def step_copy():
+                np.add.at(dst, dst_slice, src[src_slice])
+        elif inc:
             def step_copy():
                 dst[dst_slice] += src[src_slice]
+        elif repeats:
+            raise BuildError("%s: Cannot have repeated indices in "
+                             "``dst_slice`` when copy is not an increment"
+                             % self)
         else:
             def step_copy():
                 dst[dst_slice] = src[src_slice]

nengo/tests/test_connection.py

@@ -613,6 +613,68 @@ def test_slicing_function(Simulator, plt, seed):
     assert np.allclose(w, y, atol=0.1)
 
 
+def test_list_indexing(Simulator, plt, seed):
+
+    with nengo.Network(seed=seed) as model:
+        u = nengo.Node([-1, 1])
+        a = nengo.Ensemble(40, dimensions=1)
+        b = nengo.Ensemble(40, dimensions=1, radius=2.2)
+        c = nengo.Ensemble(80, dimensions=2, radius=1.3)
+        d = nengo.Ensemble(80, dimensions=2, radius=1.3)
+        nengo.Connection(u[[0, 1]], a[[0, 0]])
+        nengo.Connection(u[[1, 1]], b[[0, 0]])
+        nengo.Connection(u[[0, 1]], c[[0, 1]])
+        nengo.Connection(u[[1, 1]], d[[0, 1]])
+
+        a_probe = nengo.Probe(a, synapse=0.03)
+        b_probe = nengo.Probe(b, synapse=0.03)
+        c_probe = nengo.Probe(c, synapse=0.03)
+        d_probe = nengo.Probe(d, synapse=0.03)
+
+    with Simulator(model) as sim:
+        sim.run(0.2)
+
+    t = sim.trange()
+    a_data = sim.data[a_probe]
+    b_data = sim.data[b_probe]
+    c_data = sim.data[c_probe]
+    d_data = sim.data[d_probe]
+
+    line = plt.plot(t, a_data)
+    plt.axhline(0, color=line[0].get_color())
+    assert np.allclose(a_data[t > 0.15], [0], atol=0.1)
+    line = plt.plot(t, b_data)
+    plt.axhline(2, color=line[0].get_color())
+    assert np.allclose(b_data[t > 0.15], [2], atol=0.1)
+    line = plt.plot(t, c_data)
+    plt.axhline(-1, color=line[0].get_color())
+    assert np.allclose(c_data[t > 0.15], [-1, 1], atol=0.1)
+    line = plt.plot(t, d_data)
+    plt.axhline(1, color=line[1].get_color())
+    assert np.allclose(d_data[t > 0.15], [1, 1], atol=0.1)
+
+
+def test_boolean_indexing(Simulator, rng, plt):
+    D = 10
+    mu = np.arange(D) % 2 == 0
+    mv = np.arange(D) % 2 == 1
+    x = rng.uniform(-1, 1, size=D)
+    y = np.zeros(D)
+    y[mv] = x[mu]
+
+    with nengo.Network() as model:
+        u = nengo.Node(x)
+        v = nengo.Node(size_in=D)
+        nengo.Connection(u[mu], v[mv], synapse=None)
+        v_probe = nengo.Probe(v)
+
+    with Simulator(model) as sim:
+        sim.run(0.01)
+
+    plt.plot(sim.trange(), sim.data[v_probe])
+    assert np.allclose(sim.data[v_probe][1:], y, atol=1e-5, rtol=1e-3)
+
+
 def test_set_weight_solver():
     with nengo.Network():
         a = nengo.Ensemble(10, 2)

nengo/utils/testing.py

@@ -24,6 +24,9 @@ def __init__(self, *args, **kwargs):
     def __call__(self, *args, **kwargs):
         return Mock()
 
+    def __getitem__(self, key):
+        return Mock()
+
     def __mul__(self, other):
         return 1.0