Improve Bayesian posterior displays and DREAM CLI robustness

docs/docs/quick-reference/index.md

@@ -306,6 +306,18 @@ project.display.fit.correlations()
 project.display.pattern(expt_name='hrpt')
 ```
 
+After a Bayesian fit, inspect posterior displays:
+
+```python
+project.display.posterior.distribution(param)
+project.display.posterior.distribution()
+project.display.posterior.pairs()
+project.display.posterior.predictive(expt_name='hrpt')
+```
+
+Call `project.display.posterior.distribution()` without `param` to plot
+the marginal distribution for each free parameter one by one.
+
 ## Add Simple Constraints
 
 Create aliases from parameter objects, then define a constraint

docs/docs/tutorials/ed-21.ipynb

@@ -692,8 +692,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "for param in project.free_parameters:\n",
-    "    project.display.posterior.distribution(param)"
+    "project.display.posterior.distribution()"
    ]
   },
   {

docs/docs/tutorials/ed-21.py

@@ -329,8 +329,7 @@
 # multimodality.
 
 # %%
-for param in project.free_parameters:
-    project.display.posterior.distribution(param)
+project.display.posterior.distribution()
 
 # %% [markdown]
 # Finally, the posterior predictive plot propagates the sampled parameter

docs/docs/tutorials/ed-22.ipynb

@@ -570,8 +570,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "for param in project.free_parameters:\n",
-    "    project.display.posterior.distribution(param)"
+    "project.display.posterior.distribution()"
    ]
   },
   {

docs/docs/tutorials/ed-22.py

@@ -257,8 +257,7 @@
 # multimodality.
 
 # %%
-for param in project.free_parameters:
-    project.display.posterior.distribution(param)
+project.display.posterior.distribution()
 
 # %% [markdown]
 # Finally, the posterior predictive plot propagates the sampled

pyproject.toml

@@ -24,8 +24,6 @@ classifiers = [
 requires-python = '>=3.12'
 dependencies = [
   'numpy',          # Numerical computing library
-  'colorama',       # Color terminal output
-  'tabulate',       # Pretty-print tabular data for terminal output
   'asciichartpy',   # ASCII charts for terminal output
   'pooch',          # Data downloader
   'typer',          # Command-line interface creation

src/easydiffraction/analysis/fit_helpers/tracking.py

@@ -11,6 +11,7 @@
 from easydiffraction.analysis.fit_helpers.metrics import calculate_reduced_chi_square
 from easydiffraction.display.progress import ACTIVITY_LABEL_BURN_IN
 from easydiffraction.display.progress import ACTIVITY_LABEL_FITTING
+from easydiffraction.display.progress import ACTIVITY_LABEL_PROCESSING
 from easydiffraction.display.progress import ACTIVITY_LABEL_SAMPLING
 from easydiffraction.display.progress import ActivityIndicator
 from easydiffraction.display.progress import _TerminalLiveHandle as _SharedTerminalLiveHandle
@@ -595,7 +596,7 @@ def _replace_last_tracking_row(self, row: list[str]) -> None:
 
     def _default_activity_label(self) -> str:
         if self._tracking_mode == TRACKING_MODE_SAMPLER:
-            return ACTIVITY_LABEL_SAMPLING
+            return ACTIVITY_LABEL_PROCESSING
         return ACTIVITY_LABEL_FITTING
 
     @staticmethod

src/easydiffraction/analysis/minimizers/bumps_dream.py

@@ -4,7 +4,9 @@
 
 from __future__ import annotations
 
+import multiprocessing
 import random
+import sys
 from dataclasses import dataclass
 
 import numpy as np
@@ -726,14 +728,65 @@
         if self.parallel == 1:
             return None
 
-        if not can_pickle(problem):
+        if self._requires_serial_mapper_for_spawn_main_module():
             log.warning(
-                'DREAM parallel evaluation requires a picklable '
-                'problem; falling back to serial execution.'
+                'DREAM parallel evaluation requires an import-safe main '
+                'module on spawn-based multiprocessing; falling back to '
+                'serial execution.'
             )
             return None
 
-        return MPMapper.start_mapper(problem, [], cpus=self.parallel)
+        shared_display_handle = getattr(self.tracker, '_shared_display_handle', None)
+        activity_indicator = getattr(self.tracker, '_activity_indicator', None)
+        if shared_display_handle is not None:
+            self.tracker._set_shared_display_handle(None)
+        if activity_indicator is not None:
+            self.tracker._activity_indicator = None
+
+        try:
+            if not can_pickle(problem):
+                log.warning(
+                    'DREAM parallel evaluation requires a picklable '
+                    'problem; falling back to serial execution.'
+                )
+                return None
+
+            return MPMapper.start_mapper(problem, [], cpus=self.parallel)
+        except RuntimeError as error:
+            message = str(error)
+            if 'bootstrapping phase' not in message:
+                raise
+            log.warning(
+                'DREAM parallel evaluation requires an import-safe main '
+                'module on spawn-based multiprocessing; falling back to '
+                'serial execution.'
+            )
+            return None
+        finally:
+            if activity_indicator is not None:
+                self.tracker._activity_indicator = activity_indicator
+            if shared_display_handle is not None:
+                self.tracker._set_shared_display_handle(shared_display_handle)
+
+    @staticmethod
+    def _requires_serial_mapper_for_spawn_main_module() -> bool:
+        """
+        Return whether direct-script spawn startup should stay serial.
+        """
+        start_method = multiprocessing.get_start_method(allow_none=True)
+        if start_method is None:
+            start_method = multiprocessing.get_start_method()
+        if start_method != 'spawn':
+            return False
+
+        main_module = sys.modules.get('__main__')
+        if main_module is None:
+            return False
+
+        return (
+            getattr(main_module, '__file__', None) is not None
+            and getattr(main_module, '__spec__', None) is None
+        )
 
     @staticmethod
     def _execute_driver(*, driver: FitDriver, random_seed: int) -> _DreamDriverResult:

src/easydiffraction/display/plotters/ascii.py

@@ -10,6 +10,8 @@
 
 from __future__ import annotations
 
+import shutil
+
 import asciichartpy
 import numpy as np
 
@@ -22,13 +24,55 @@
 DEFAULT_COLORS = {
     'meas': asciichartpy.blue,
     'calc': asciichartpy.red,
+    'posterior': asciichartpy.red,
+    'density': asciichartpy.green,
     'resid': asciichartpy.green,
 }
+ASCII_CHART_OFFSET = 3
+ASCII_CHART_LEFT_PADDING = 15
+ASCII_CHART_FALLBACK_POINT_COUNT = 80
+ASCII_CHART_MIN_POINT_COUNT = 2
 
 
 class AsciiPlotter(PlotterBase):
     """Terminal-based plotter using ASCII art."""
 
+    @staticmethod
+    def _chart_point_count() -> int:
+        """Return the number of points that fit the current terminal."""
+        fallback_columns = (
+            ASCII_CHART_FALLBACK_POINT_COUNT + ASCII_CHART_OFFSET + ASCII_CHART_LEFT_PADDING
+        )
+        columns = shutil.get_terminal_size(fallback=(fallback_columns, DEFAULT_HEIGHT)).columns
+        return max(
+            ASCII_CHART_MIN_POINT_COUNT,
+            columns - ASCII_CHART_OFFSET - ASCII_CHART_LEFT_PADDING,
+        )
+
+    @classmethod
+    def _resample_series_for_chart(
+        cls,
+        y_series: object,
+    ) -> list[list[float]]:
+        """Return y-series resampled to the available chart width."""
+        target_point_count = cls._chart_point_count()
+        resampled_series: list[list[float]] = []
+        for series in y_series:
+            series_array = np.ravel(np.asarray(series, dtype=float))
+            if (
+                series_array.size <= target_point_count
+                or series_array.size < ASCII_CHART_MIN_POINT_COUNT
+            ):
+                resampled_series.append(series_array.tolist())
+                continue
+
+            source_positions = np.linspace(0.0, 1.0, series_array.size)
+            target_positions = np.linspace(0.0, 1.0, target_point_count)
+            resampled_series.append(
+                np.interp(target_positions, source_positions, series_array).tolist()
+            )
+        return resampled_series
+
     @staticmethod
     def _get_legend_item(label: str) -> str:
         """
@@ -94,8 +138,12 @@ def plot_powder(
         if height is None:
             height = DEFAULT_HEIGHT
         colors = [DEFAULT_COLORS[label] for label in labels]
-        config = {'height': height, 'colors': colors}
-        y_series = [y.tolist() for y in y_series]
+        config = {
+            'height': height,
+            'colors': colors,
+            'offset': ASCII_CHART_OFFSET,
+        }
+        y_series = self._resample_series_for_chart(y_series)
 
         chart = asciichartpy.plot(y_series, config)
 

src/easydiffraction/display/plotters/base.py

@@ -191,6 +191,14 @@ class XAxisType(StrEnum):
         'mode': 'lines',
         'name': 'Total calculated (Icalc)',
     },
+    'posterior': {
+        'mode': 'lines',
+        'name': 'Max posterior',
+    },
+    'density': {
+        'mode': 'lines',
+        'name': 'Marginal density',
+    },
     'bkg': {
         'mode': 'lines',
         'name': 'Background (Ibkg)',

src/easydiffraction/display/plotters/plotly.py

@@ -38,6 +38,7 @@
     'meas': 'rgb(31, 119, 180)',
     'bkg': 'rgb(140, 140, 140)',
     'calc': 'rgb(214, 39, 40)',
+    'posterior': 'rgb(214, 39, 40)',
     'resid': 'rgb(44, 160, 44)',
 }