New parallel coordinates plot (facebook#2590)

Summary:
Pull Request resolved: facebook#2590

An improved version of the parallel coordinates analysis I implemented earlier this year, now refactored with AnalysisCards.

Main improvements include:
* Ability to infer what metric to use based on the OptimizationConfig if one is not provided
* Compatibility with ChoiceParameters and FixedParameters
* Truncation of long parameter and metric names where appropriate

NOTE: This analysis introduces a number of helper functions in parallel_coordinates.py -- as we add more analyses these should be refactored out into analysis/plotly/utils.py or analysis/utils.py as appropriate.

Differential Revision: D59927703

ax/analysis/plotly/__init__.py

@@ -3,6 +3,9 @@
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
 
+from ax.analysis.plotly.parallel_coordinates.parallel_coordinates import (
+    ParallelCoordinatesPlot,
+)
 from ax.analysis.plotly.plotly_analysis import PlotlyAnalysis, PlotlyAnalysisCard
 
-__all__ = ["PlotlyAnalysis", "PlotlyAnalysisCard"]
+__all__ = ["PlotlyAnalysis", "PlotlyAnalysisCard", "ParallelCoordinatesPlot"]

ax/analysis/plotly/parallel_coordinates/parallel_coordinates.py

@@ -0,0 +1,175 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from typing import Any, Dict, Optional
+
+import numpy as np
+import pandas as pd
+from ax.analysis.analysis import AnalysisCardLevel
+
+from ax.analysis.plotly.plotly_analysis import PlotlyAnalysis, PlotlyAnalysisCard
+from ax.core.experiment import Experiment
+from ax.core.objective import MultiObjective, ScalarizedObjective
+from ax.exceptions.core import UnsupportedError, UserInputError
+from ax.modelbridge.generation_strategy import GenerationStrategy
+from plotly import graph_objects as go
+
+
+class ParallelCoordinatesPlot(PlotlyAnalysis):
+    """
+    Plotly Parcoords plot for a single metric, with one line per arm and dimensions for
+    each parameter in the search space. This plot is useful for understanding how
+    thoroughly the search space is explored as well as for identifying if there is any
+    clusertering for either good or bad parameterizations.
+
+    The DataFrame computed will contain one row per arm and the following columns:
+        - arm_name: The name of the arm
+        - METRIC_NAME: The observed mean of the metric specified
+        - **PARAMETER_NAME: The value of said parameter for the arm, for each parameter
+    """
+
+    def __init__(self, metric_name: Optional[str] = None) -> None:
+        """
+        Args:
+            metric_name: The name of the metric to plot. If not specified the objective
+                will be used. Note that the metric cannot be inferred for
+                multi-objective or scalarized-objective experiments.
+        """
+
+        self.metric_name = metric_name
+
+    def compute(
+        self,
+        experiment: Optional[Experiment] = None,
+        generation_strategy: Optional[GenerationStrategy] = None,
+    ) -> PlotlyAnalysisCard:
+        if experiment is None:
+            raise UserInputError("ParallelCoordinatesPlot requires an Experiment")
+
+        metric_name = self.metric_name or _select_metric(experiment=experiment)
+
+        df = _prepare_data(experiment=experiment, metric=metric_name)
+        fig = _prepare_plot(df=df, metric_name=metric_name)
+
+        return PlotlyAnalysisCard(
+            name=self.__class__.__name__,
+            title=f"Parallel Coordinates for {metric_name}",
+            subtitle="View arm parameterizations with their respective metric values",
+            level=AnalysisCardLevel.HIGH,
+            df=df,
+            blob=fig,
+        )
+
+
+def _prepare_data(experiment: Experiment, metric: str) -> pd.DataFrame:
+    data_df = experiment.lookup_data().df
+    filtered_df = data_df.loc[data_df["metric_name"] == metric]
+
+    if filtered_df.empty:
+        raise ValueError(f"No data found for metric {metric}")
+
+    records = [
+        {
+            "arm_name": arm.name,
+            **arm.parameters,
+            metric: _find_mean_by_arm_name(df=filtered_df, arm_name=arm.name),
+        }
+        for trial in experiment.trials.values()
+        for arm in trial.arms
+    ]
+
+    return pd.DataFrame.from_records(records)
+
+
+def _prepare_plot(df: pd.DataFrame, metric_name: str) -> go.Figure:
+
+    # ParCoords requires that the dimensions are specified on continuous scales, so
+    # ChoiceParameters and FixedParameters must be preprocessed to allow for
+    # appropriate plotting.
+    parameter_dimensions = [
+        _get_parameter_dimension(series=df[col])
+        for col in df.columns
+        if col != "arm_name" and col != metric_name
+    ]
+
+    return go.Figure(
+        go.Parcoords(
+            line={
+                "color": df[metric_name],
+                "showscale": True,
+            },
+            dimensions=[
+                *parameter_dimensions,
+                {
+                    "label": _truncate_label(label=metric_name),
+                    "values": df[metric_name].tolist(),
+                },
+            ],
+        )
+    )
+
+
+def _select_metric(experiment: Experiment) -> str:
+    if experiment.optimization_config is not None:
+        objective = experiment.optimization_config.objective
+        if isinstance(objective, MultiObjective):
+            raise UnsupportedError(
+                "Cannot infer metric to plot from MultiObjective, please "
+                "specify a metric"
+            )
+        if isinstance(objective, ScalarizedObjective):
+            raise UnsupportedError(
+                "Cannot infer metric to plot from ScalarizedObjective, please "
+                "specify a metric"
+            )
+        return experiment.optimization_config.objective.metric.name
+    else:
+        raise ValueError(
+            "Cannot infer metric to plot from Experiment without OptimizationConfig"
+        )
+
+
+def _find_mean_by_arm_name(
+    df: pd.DataFrame,
+    arm_name: str,
+) -> float:
+    # Given a dataframe with arm_name and mean columns, find the mean for a given
+    # arm_name. If an arm_name is not found (as can happen if the arm is still running
+    # or has failed) return NaN.
+    series = df.loc[df["arm_name"] == arm_name]["mean"]
+
+    if series.empty:
+        return np.nan
+
+    return series.item()
+
+
+def _get_parameter_dimension(series: pd.Series) -> Dict[str, Any]:
+    # For numeric parameters allow Plotly to infer tick attributes. Note: booleans are
+    # considered numeric, but in this case we want to treat them as categorical.
+    if pd.api.types.is_numeric_dtype(series) and not pd.api.types.is_bool_dtype(series):
+        return {
+            "tickvals": None,
+            "ticktext": None,
+            "label": _truncate_label(label=str(series.name)),
+            "values": series.tolist(),
+        }
+
+    # For non-numeric parameters, sort, map onto an integer scale, and provide
+    # corresponding tick attributes
+    mapping = {v: k for k, v in enumerate(sorted(series.unique()))}
+
+    return {
+        "tickvals": [_truncate_label(label=str(val)) for val in mapping.values()],
+        "ticktext": [_truncate_label(label=str(key)) for key in mapping.keys()],
+        "label": _truncate_label(label=str(series.name)),
+        "values": series.map(mapping).tolist(),
+    }
+
+
+def _truncate_label(label: str, n: int = 8) -> str:
+    if len(label) > n:
+        return label[:n] + "..."
+    return label

ax/analysis/plotly/parallel_coordinates/tests/test_parallel_coordinates.py

@@ -0,0 +1,89 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import pandas as pd
+from ax.analysis.analysis import AnalysisCardLevel
+from ax.analysis.plotly.parallel_coordinates.parallel_coordinates import (
+    _get_parameter_dimension,
+    _select_metric,
+    ParallelCoordinatesPlot,
+)
+from ax.exceptions.core import UnsupportedError, UserInputError
+from ax.utils.common.testutils import TestCase
+from ax.utils.testing.core_stubs import (
+    get_branin_experiment,
+    get_experiment_with_multi_objective,
+    get_experiment_with_scalarized_objective_and_outcome_constraint,
+)
+
+
+class TestParallelCoordinatesPlot(TestCase):
+    def test_compute(self) -> None:
+        analysis = ParallelCoordinatesPlot("branin")
+        experiment = get_branin_experiment(with_completed_trial=True)
+
+        with self.assertRaisesRegex(UserInputError, "requires an Experiment"):
+            analysis.compute()
+
+        card = analysis.compute(experiment=experiment)
+        self.assertEqual(card.name, "ParallelCoordinatesPlot")
+        self.assertEqual(card.title, "Parallel Coordinates for branin")
+        self.assertEqual(
+            card.subtitle,
+            "View arm parameterizations with their respective metric values",
+        )
+        self.assertEqual(card.level, AnalysisCardLevel.HIGH)
+        self.assertEqual({*card.df.columns}, {"arm_name", "branin", "x1", "x2"})
+        self.assertIsNotNone(card.blob)
+        self.assertEqual(card.blob_type, "plotly")
+
+        analysis_no_metric = ParallelCoordinatesPlot()
+        _ = analysis_no_metric.compute(experiment=experiment)
+
+    def test_select_metric(self) -> None:
+        experiment = get_branin_experiment()
+        experiment_no_optimization_config = get_branin_experiment(
+            has_optimization_config=False
+        )
+        experiment_multi_objective = get_experiment_with_multi_objective()
+        experiment_scalarized_objective = (
+            get_experiment_with_scalarized_objective_and_outcome_constraint()
+        )
+
+        self.assertEqual(_select_metric(experiment=experiment), "branin")
+
+        with self.assertRaisesRegex(ValueError, "OptimizationConfig"):
+            _select_metric(experiment=experiment_no_optimization_config)
+
+        with self.assertRaisesRegex(UnsupportedError, "MultiObjective"):
+            _select_metric(experiment=experiment_multi_objective)
+
+        with self.assertRaisesRegex(UnsupportedError, "ScalarizedObjective"):
+            _select_metric(experiment=experiment_scalarized_objective)
+
+    def test_get_parameter_dimension(self) -> None:
+        range_series = pd.Series([0, 1, 2, 3], name="range")
+        range_dimension = _get_parameter_dimension(series=range_series)
+        self.assertEqual(
+            range_dimension,
+            {
+                "tickvals": None,
+                "ticktext": None,
+                "label": "range",
+                "values": range_series.tolist(),
+            },
+        )
+
+        choice_series = pd.Series(["foo", "bar", "baz"], name="choice")
+        choice_dimension = _get_parameter_dimension(series=choice_series)
+        self.assertEqual(
+            choice_dimension,
+            {
+                "tickvals": ["0", "1", "2"],
+                "ticktext": ["bar", "baz", "foo"],
+                "label": "choice",
+                "values": [2, 0, 1],
+            },
+        )