Added api docs gen (copy from TFQ).

cirq/contrib/svg/svg.py

@@ -6,12 +6,25 @@
     import cirq
 
 QBLUE = '#1967d2'
+FONT = "Arial"
+
+
+def fixup_text(text: str):
+    if '\n' in text:
+        return '?'
+    if '[<virtual>]' in text:
+        # https://github.com/quantumlib/Cirq/issues/2905
+        # TODO: escape angle brackets when you actually want to display tags
+        return text.replace('[<virtual>]', '')  # coverage: ignore
+    if '[cirq.VirtualTag()]' in text:
+        # https://github.com/quantumlib/Cirq/issues/2905
+        return text.replace('[cirq.VirtualTag()]', '')
+    return text
 
 
 def _get_text_width(t: str) -> float:
-    if '\n' in t:
-        return _get_text_width('?')
-    tp = matplotlib.textpath.TextPath((0, 0), t, size=14, prop='Arial')
+    t = fixup_text(t)
+    tp = matplotlib.textpath.TextPath((0, 0), t, size=14, prop=FONT)
     bb = tp.get_extents()
     return bb.width + 10
 
@@ -30,7 +43,8 @@ def _rect(x: float,
 def _text(x: float, y: float, text: str, fontsize: int = 14):
     """Draw SVG <text> text."""
     return f'<text x="{x}" y="{y}" dominant-baseline="middle" ' \
-           f'text-anchor="middle" font-size="{fontsize}px">{text}</text>'
+           f'text-anchor="middle" font-size="{fontsize}px" ' \
+           f'font-family="{FONT}">{text}</text>'
 
 
 def _fit_horizontal(tdd: 'cirq.TextDiagramDrawer',
@@ -208,13 +222,10 @@ def tdd_to_svg(
         if v.text == '×':
             t += _text(x, y + 3, '×', fontsize=40)
             continue
-        if '\n' in v.text:
-            t += _rect(boxx, boxy, boxwidth, boxheight)
-            t += _text(x, y, '?', fontsize=18)
-            continue
 
+        v_text = fixup_text(v.text)
         t += _rect(boxx, boxy, boxwidth, boxheight)
-        t += _text(x, y, v.text, fontsize=14 if len(v.text) > 1 else 18)
+        t += _text(x, y, v_text, fontsize=14 if len(v_text) > 1 else 18)
 
     t += '</svg>'
     return t

cirq/contrib/svg/svg_test.py

@@ -22,6 +22,15 @@ def test_svg():
     assert '</svg>' in svg_text
 
 
+def test_svg_noise():
+    noise_model = cirq.ConstantQubitNoiseModel(cirq.DepolarizingChannel(p=1e-3))
+    q = cirq.LineQubit(0)
+    circuit = cirq.Circuit(cirq.X(q))
+    circuit = cirq.Circuit(noise_model.noisy_moments(circuit.moments, [q]))
+    svg = circuit_to_svg(circuit)
+    assert '>D(0.001)</text>' in svg
+
+
 def test_validation():
     with pytest.raises(ValueError):
         circuit_to_svg(cirq.Circuit())

cirq/study/visualize.py

@@ -24,8 +24,6 @@ def plot_state_histogram(result: trial_result.TrialResult) -> np.ndarray:
 
     States is a bitstring representation of all the qubit states in a single
     result.
-    Currently this function assumes each measurement gate applies to only
-    a single qubit.
 
     Args:
         result: The trial results to plot.
@@ -39,17 +37,15 @@ def plot_state_histogram(result: trial_result.TrialResult) -> np.ndarray:
     # This allows cirq to be usable without python3-tk.
     import matplotlib.pyplot as plt
 
-    num_qubits = len(result.measurements.keys())
+    num_qubits = sum([value.shape[1] for value in result.measurements.values()])
     states = 2**num_qubits
     values = np.zeros(states)
-
     # measurements is a dict of {measurement gate key:
     #                            array(repetitions, boolean result)}
     # Convert this to an array of repetitions, each with an array of booleans.
     # e.g. {q1: array([[True, True]]), q2: array([[False, False]])}
     #      --> array([[True, False], [True, False]])
-    measurement_by_result = np.array([
-        v.transpose()[0] for k, v in result.measurements.items()]).transpose()
+    measurement_by_result = np.hstack(list(result.measurements.values()))
 
     for meas in measurement_by_result:
         # Convert each array of booleans to a string representation.

cirq/study/visualize_test.py

@@ -38,3 +38,30 @@ def test_plot_state_histogram():
     expected_values = [0., 0., 0., 5.]
 
     np.testing.assert_equal(values_plotted, expected_values)
+
+
+def test_plot_state_histogram_multi_1():
+    pl.switch_backend('PDF')
+    qubits = cirq.LineQubit.range(4)
+    c = cirq.Circuit(
+        cirq.X.on_each(*qubits[1:]),
+        cirq.measure(*qubits),  # One multi-qubit measurement
+    )
+    r = cirq.sample(c, repetitions=5)
+    values_plotted = visualize.plot_state_histogram(r)
+    expected_values = [0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0]
+    np.testing.assert_equal(values_plotted, expected_values)
+
+
+def test_plot_state_histogram_multi_2():
+    pl.switch_backend('PDF')
+    qubits = cirq.LineQubit.range(4)
+    c = cirq.Circuit(
+        cirq.X.on_each(*qubits[1:]),
+        cirq.measure(*qubits[:2]),  # One multi-qubit measurement
+        cirq.measure_each(*qubits[2:]),  # Multiple single-qubit measurement
+    )
+    r = cirq.sample(c, repetitions=5)
+    values_plotted = visualize.plot_state_histogram(r)
+    expected_values = [0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0]
+    np.testing.assert_equal(values_plotted, expected_values)

cirq/testing/random_circuit.py

@@ -96,8 +96,8 @@ def random_circuit(qubits: Union[Sequence[ops.Qid], int],
         raise ValueError('At least one qubit must be specified.')
     gate_domain = {k: v for k, v in gate_domain.items() if v <= n_qubits}
     if not gate_domain:
-        raise ValueError(f'After removing gates that act on less that '
-                         '{n_qubits}, gate_domain had no gates.')
+        raise ValueError(f'After removing gates that act on less than '
+                         f'{n_qubits} qubits, gate_domain had no gates.')
     max_arity = max(gate_domain.values())
 
     prng = value.parse_random_state(random_state)