Bug fixes and improvements for LayerError visualization tool (#1973)

* modifications * tests * better docs * oops * Update qiskit_ibm_runtime/utils/noise_learner_result.py Co-authored-by: joshuasn <[email protected]> * Update qiskit_ibm_runtime/visualization/draw_layer_error_map.py Co-authored-by: joshuasn <[email protected]> --------- Co-authored-by: joshuasn <[email protected]>
Qiskit · Oct 16, 2024 · 0f659ec · 0f659ec
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diff --git a/qiskit_ibm_runtime/utils/noise_learner_result.py b/qiskit_ibm_runtime/utils/noise_learner_result.py
@@ -223,9 +223,11 @@ def draw_map(
         embedding: Union[Embedding, BackendV2],
         colorscale: str = "Bluered",
         color_no_data: str = "lightgray",
+        color_out_of_scale: str = "lightgreen",
         num_edge_segments: int = 16,
         edge_width: float = 4,
         height: int = 500,
+        highest_rate: Optional[float] = None,
         background_color: str = "white",
         radius: float = 0.25,
         width: int = 800,
@@ -238,12 +240,46 @@ def draw_map(
                 to draw the layer error on, or a backend to generate an :class:`~.Embedding` for.
             colorscale: The colorscale used to show the rates of this layer error.
             color_no_data: The color used for qubits and edges for which no data is available.
+            color_out_of_scale: The color used for rates with value greater than ``highest_rate``.
             num_edge_segments: The number of equal-sized segments that edges are made of.
             edge_width: The line width of the edges in pixels.
             height: The height of the returned figure.
+            highest_rate: The highest rate, used to normalize all other rates before choosing their
+                colors. If ``None``, it defaults to the highest value found in the ``layer_error``.
             background_color: The background color.
             radius: The radius of the pie charts representing the qubits.
             width: The width of the returned figure.
+
+            .. code:: python
+
+                from qiskit import QuantumCircuit
+                from qiskit.quantum_info import PauliList
+                from qiskit_ibm_runtime.utils.embeddings import Embedding
+                from qiskit_ibm_runtime.utils.noise_learner_result import LayerError, PauliLindbladError
+
+                # A five-qubit 1-D embedding with nearest neighbouring connectivity
+                coordinates1 = [(0, 0), (0, 1), (0, 2), (0, 3), (0, 4), (0, 5)]
+                coupling_map1 = [(0, 1), (1, 2), (2, 3), (3, 4), (4, 5)]
+                embedding1 = Embedding(coordinates1, coupling_map1)
+
+                # A six-qubit horseshoe-shaped embedding with nearest neighbouring connectivity
+                coordinates2 = [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2)]
+                coupling_map2 = [(0, 1), (1, 2), (0, 3), (3, 4), (4, 5)]
+                embedding2 = Embedding(coordinates2, coupling_map2)
+
+                # A LayerError object
+                circuit = QuantumCircuit(4)
+                qubits = [1, 2, 3, 4]
+                generators = PauliList(["IIIX", "IIXI", "IXII", "YIII", "ZIII", "XXII", "ZZII"])
+                rates = [0.01, 0.01, 0.01, 0.005, 0.02, 0.01, 0.01]
+                error = PauliLindbladError(generators, rates)
+                layer_error = LayerError(circuit, qubits, error)
+
+                # Draw the layer error on embedding1
+                layer_error.draw_map(embedding1)
+
+                # Draw the layer error on embedding2
+                layer_error.draw_map(embedding2)
         """
         # pylint: disable=import-outside-toplevel, cyclic-import
 
@@ -254,9 +290,11 @@ def draw_map(
             embedding,
             colorscale,
             color_no_data,
+            color_out_of_scale,
             num_edge_segments,
             edge_width,
             height,
+            highest_rate,
             background_color,
             radius,
             width,

diff --git a/qiskit_ibm_runtime/visualization/draw_layer_error_map.py b/qiskit_ibm_runtime/visualization/draw_layer_error_map.py
@@ -13,7 +13,7 @@
 """Functions to visualize :class:`~.NoiseLearnerResult` objects."""
 
 from __future__ import annotations
-from typing import Dict, Tuple, Union, TYPE_CHECKING
+from typing import Dict, Optional, Tuple, Union, TYPE_CHECKING
 
 import numpy as np
 from qiskit.providers.backend import BackendV2
@@ -31,9 +31,11 @@ def draw_layer_error_map(
     embedding: Union[Embedding, BackendV2],
     colorscale: str = "Bluered",
     color_no_data: str = "lightgray",
+    color_out_of_scale: str = "lightgreen",
     num_edge_segments: int = 16,
     edge_width: float = 4,
     height: int = 500,
+    highest_rate: Optional[float] = None,
     background_color: str = "white",
     radius: float = 0.25,
     width: int = 800,
@@ -47,9 +49,12 @@ def draw_layer_error_map(
             to draw the layer error on, or a backend to generate an :class:`~.Embedding` for.
         colorscale: The colorscale used to show the rates of ``layer_error``.
         color_no_data: The color used for qubits and edges for which no data is available.
+        color_out_of_scale: The color used for rates with value greater than ``highest_rate``.
         num_edge_segments: The number of equal-sized segments that edges are made of.
         edge_width: The line width of the edges in pixels.
         height: The height of the returned figure.
+        highest_rate: The highest rate, used to normalize all other rates before choosing their
+            colors. If ``None``, it defaults to the highest value found in the ``layer_error``.
         background_color: The background color.
         radius: The radius of the pie charts representing the qubits.
         width: The width of the returned figure.
@@ -83,24 +88,28 @@ def draw_layer_error_map(
     # A set of unique edges ``(i, j)``, with ``i < j``.
     edges = set(tuple(sorted(edge)) for edge in list(coupling_map))
 
-    # The highest rate, used to normalize all other rates before choosing their colors.
-    high_scale = 0
+    # The highest rate
+    max_rate = 0
 
     # Initialize a dictionary of one-qubit errors
+    qubits = layer_error.qubits
     error_1q = layer_error.error.restrict_num_bodies(1)
-    rates_1q: Dict[int, Dict[str, float]] = {qubit: {} for qubit in layer_error.qubits}
+    rates_1q: Dict[int, Dict[str, float]] = {qubit: {} for qubit in qubits}
     for pauli, rate in zip(error_1q.generators, error_1q.rates):
-        qubit = np.where(pauli.x | pauli.z)[0][0]
-        rates_1q[qubit][str(pauli[qubit])] = rate
-        high_scale = max(high_scale, rate)
+        qubit_idx = np.where(pauli.x | pauli.z)[0][0]
+        rates_1q[qubits[qubit_idx]][str(pauli[qubit_idx])] = rate
+        max_rate = max(max_rate, rate)
 
     # Initialize a dictionary of two-qubit errors
     error_2q = layer_error.error.restrict_num_bodies(2)
-    rates_2q: Dict[Tuple[int, ...], Dict[str, float]] = {qubits: {} for qubits in edges}
+    rates_2q: Dict[Tuple[int, ...], Dict[str, float]] = {edge: {} for edge in edges}
     for pauli, rate in zip(error_2q.generators, error_2q.rates):
-        qubits = tuple(sorted([i for i, q in enumerate(pauli) if str(q) != "I"]))
-        rates_2q[qubits][str(pauli[[qubits[0], qubits[1]]])] = rate
-        high_scale = max(high_scale, rate)
+        err_idxs = tuple(sorted([i for i, q in enumerate(pauli) if str(q) != "I"]))
+        edge = (qubits[err_idxs[0]], qubits[err_idxs[1]])
+        rates_2q[edge][str(pauli[[err_idxs[0], err_idxs[1]]])] = rate
+        max_rate = max(max_rate, rate)
+
+    highest_rate = highest_rate if highest_rate else max_rate
 
     # A discreet colorscale that contains 1000 hues.
     discreet_colorscale = sample_colorscale(colorscale, np.linspace(0, 1, 1000))
@@ -122,7 +131,10 @@ def draw_layer_error_map(
                 for i in range(num_edge_segments)
             ]
             color = [
-                get_rgb_color(discreet_colorscale, v / high_scale, color_no_data) for v in all_vals
+                get_rgb_color(
+                    discreet_colorscale, v / highest_rate, color_no_data, color_out_of_scale
+                )
+                for v in all_vals
             ]
             hoverinfo_2q = ""
             for pauli, rate in rates_2q[(q1, q2)].items():
@@ -172,7 +184,9 @@ def draw_layer_error_map(
         hoverinfo = ""
         for pauli, angle in [("Z", -30), ("X", 90), ("Y", 210)]:
             rate = rates_1q.get(qubit, {}).get(pauli, 0)
-            fillcolor = get_rgb_color(discreet_colorscale, rate / high_scale, color_no_data)
+            fillcolor = get_rgb_color(
+                discreet_colorscale, rate / highest_rate, color_no_data, color_out_of_scale
+            )
             shapes += [
                 {
                     "type": "path",
@@ -191,12 +205,16 @@ def draw_layer_error_map(
         fig.add_annotation(x=x + 0.3, y=y + 0.4, text=f"{qubit}", showarrow=False)
 
     # Add the hoverinfo for the pie charts
+    marker_colors = []
+    for qubit in rates_1q:
+        max_qubit_rate = max(rates_1q[qubit].values())
+        marker_colors.append(max_qubit_rate if max_qubit_rate <= highest_rate else highest_rate)
     nodes = go.Scatter(
         x=xs,
         y=ys,
         mode="markers",
         marker={
-            "color": list({qubit: max(rates_1q[qubit].values()) for qubit in rates_1q}.values()),
+            "color": marker_colors,
             "colorscale": colorscale,
             "showscale": True,
         },

diff --git a/qiskit_ibm_runtime/visualization/utils.py b/qiskit_ibm_runtime/visualization/utils.py
@@ -46,7 +46,9 @@ def pie_slice(angle_st: float, angle_end: float, x: float, y: float, radius: flo
     return path
 
 
-def get_rgb_color(discreet_colorscale: List[str], val: float, default: str) -> str:
+def get_rgb_color(
+    discreet_colorscale: List[str], val: float, default: str, color_out_of_scale: str
+) -> str:
     r"""
     Maps a float to an RGB color based on a discreet colorscale that contains
     exactly ``1000`` hues.
@@ -55,14 +57,17 @@ def get_rgb_color(discreet_colorscale: List[str], val: float, default: str) -> s
         discreet_colorscale: A discreet colorscale.
         val: A value to map to a color.
         default: A default color returned when ``val`` is ``0``.
+        color_out_of_scale: The color that is returned when ``val`` is larger than ``1``.
 
     Raises:
         ValueError: If the colorscale contains more or less than ``1000`` hues.
     """
     if len(discreet_colorscale) != 1000:
         raise ValueError("Invalid ``discreet_colorscale.``")
 
-    if val >= 1:
+    if val > 1:
+        return color_out_of_scale
+    if val == 1:
         return discreet_colorscale[-1]
     if val == 0:
         return default

diff --git a/test/unit/test_noise_learner_result.py b/test/unit/test_noise_learner_result.py
@@ -13,13 +13,13 @@
 """Tests for the classes used to instantiate noise learner results."""
 
 from unittest import skipIf
-from ddt import ddt, data
+from ddt import ddt
 
 from qiskit import QuantumCircuit
 from qiskit.quantum_info import PauliList
 from qiskit_aer import AerSimulator
 
-from qiskit_ibm_runtime.fake_provider.local_service import QiskitRuntimeLocalService
+from qiskit_ibm_runtime.fake_provider import FakeKyiv
 from qiskit_ibm_runtime.utils.noise_learner_result import PauliLindbladError, LayerError
 
 from ..ibm_test_case import IBMTestCase
@@ -95,9 +95,6 @@ class TestLayerError(IBMTestCase):
     def setUp(self):
         super().setUp()
 
-        # A local service
-        self.service = QiskitRuntimeLocalService()
-
         # A set of circuits
         c1 = QuantumCircuit(2)
         c1.cx(0, 1)
@@ -121,7 +118,7 @@ def setUp(self):
 
         # Another set of errors used in the visualization tests
         circuit = QuantumCircuit(4)
-        qubits = [0, 1, 2, 3]
+        qubits = [1, 2, 3, 4]
         generators = PauliList(["IIIX", "IIXI", "IXII", "YIII", "ZIII", "XXII", "ZZII"])
         rates = [0.01, 0.01, 0.01, 0.005, 0.02, 0.01, 0.01]
         self.layer_error_viz = LayerError(circuit, qubits, PauliLindbladError(generators, rates))
@@ -167,15 +164,12 @@ def test_no_coupling_map(self):
             self.layer_error_viz.draw_map(AerSimulator())
 
     @skipIf(not PLOTLY_INSTALLED, reason="Plotly is not installed")
-    @data(["fake_hanoi", 44], ["fake_kyiv", 160])
-    def test_plotting(self, inputs):
+    def test_plotting(self):
         r"""
         Tests the `draw_map` function to make sure that it produces the right figure.
         """
-        backend_name, n_traces = inputs
-        backend = self.service.backend(backend_name)
         fig = self.layer_error_viz.draw_map(
-            backend,
+            embedding=FakeKyiv(),
             color_no_data="blue",
             colorscale="reds",
             radius=0.2,
@@ -184,4 +178,4 @@ def test_plotting(self, inputs):
         )
 
         self.assertIsInstance(fig, go.Figure)
-        self.assertEqual(len(fig.data), n_traces)
+        self.assertEqual(len(fig.data), 160)