feat: update default histogram colors to petroff10 (#557)

* update default histogram visualization to use petroff10 color cycle
* raise matplotlib lower version bound to 3.10

Author: alexander-held

pyproject.toml

@@ -40,15 +40,14 @@ dependencies = [
     "boost_histogram>=1.0.0",  # subclassing with family, 1.02 for stdev scaling fix (currently not needed)
     "hist>=2.5.0",  # hist.intervals.poisson_interval
     "tabulate>=0.8.1",  # multiline text
-    "matplotlib>=3.5.0",  # layout kwarg for subplots
+    "matplotlib>=3.10.0",  # petroff10 color cycle
     # below are direct dependencies of cabinetry, which are also included via pyhf[iminuit]
     "numpy",
     "pyyaml",
     "iminuit",
     "jsonschema",
     "click",
     "scipy",
-    "packaging",  # for version parsing
 ]
 
 [project.scripts]
@@ -162,6 +161,5 @@ module = [
     "iminuit",
     "jsonschema",
     "scipy.*",
-    "packaging.*",
 ]
 ignore_missing_imports = true

src/cabinetry/visualize/plot_model.py

@@ -8,18 +8,11 @@
 import matplotlib as mpl
 import matplotlib.pyplot as plt
 import numpy as np
-import packaging.version
 
 from cabinetry.visualize import utils
 
 log = logging.getLogger(__name__)
 
-# handling of matplotlib<3.6
-if packaging.version.parse(mpl.__version__) < packaging.version.parse("3.6"):
-    MPL_STYLE = "seaborn-colorblind"  # pragma: no cover
-else:
-    MPL_STYLE = "seaborn-v0_8-colorblind"
-
 
 def data_mc(
     histogram_dict_list: list[dict[str, Any]],
@@ -77,7 +70,7 @@ def data_mc(
             mc_histograms_yields.append(h["yields"])
             mc_labels.append(h["label"])
 
-    mpl.style.use(MPL_STYLE)
+    mpl.style.use("petroff10")
 
     fig = plt.figure(figsize=(6, 6), layout="constrained")
     gs = fig.add_gridspec(nrows=2, ncols=1, hspace=0, height_ratios=[3, 1])
@@ -297,7 +290,7 @@ def templates(
     bin_width = bin_edges[1:] - bin_edges[:-1]
     bin_centers = 0.5 * (bin_edges[:-1] + bin_edges[1:])
 
-    mpl.style.use(MPL_STYLE)
+    mpl.style.use("petroff10")
     fig = plt.figure(figsize=(8, 6), layout="constrained")
     gs = fig.add_gridspec(nrows=2, ncols=1, hspace=0, height_ratios=[3, 1])
     ax1 = fig.add_subplot(gs[0])

src/cabinetry/visualize/plot_result.py

@@ -5,22 +5,14 @@
 import pathlib
 
 import matplotlib as mpl
+import matplotlib.layout_engine
 import matplotlib.pyplot as plt
 import numpy as np
-import packaging.version
 
 from cabinetry.visualize import utils
 
 log = logging.getLogger(__name__)
 
-# handling of matplotlib<3.6
-if packaging.version.parse(mpl.__version__) < packaging.version.parse("3.6"):
-    MPL_GEQ_36 = False  # pragma: no cover
-    MPL_STYLE = "seaborn-colorblind"  # pragma: no cover
-else:
-    MPL_GEQ_36 = True
-    MPL_STYLE = "seaborn-v0_8-colorblind"
-
 
 def correlation_matrix(
     corr_mat: np.ndarray,
@@ -152,16 +144,11 @@ def ranking(
 
     # layout to make space for legend on top
     leg_space = 1.0 / (num_pars + 3) + 0.03
-    if MPL_GEQ_36:
-        import matplotlib.layout_engine
-
-        layout = matplotlib.layout_engine.ConstrainedLayoutEngine(
-            rect=[0, 0, 1.0, 1 - leg_space]
-        )
-    else:
-        layout = None  # pragma: no cover  # layout set after figure creation instead
+    layout = matplotlib.layout_engine.ConstrainedLayoutEngine(
+        rect=[0, 0, 1.0, 1 - leg_space]
+    )
 
-    mpl.style.use(MPL_STYLE)
+    mpl.style.use("petroff10")
     fig, ax_pulls = plt.subplots(
         figsize=(8, 2.5 + num_pars * 0.45), dpi=100, layout=layout
     )
@@ -201,12 +188,12 @@ def ranking(
     )
     # pre-fit down
     pre_down = ax_impact.barh(
-        y_pos, impact_prefit_down, fill=False, linewidth=1, edgecolor="C5"
+        y_pos, impact_prefit_down, fill=False, linewidth=1, edgecolor="C9"
     )
     # post-fit up
     post_up = ax_impact.barh(y_pos, impact_postfit_up, color="C0")
     # post-fit down
-    post_down = ax_impact.barh(y_pos, impact_postfit_down, color="C5")
+    post_down = ax_impact.barh(y_pos, impact_postfit_down, color="C9")
     # nuisance parameter pulls
     pulls = ax_pulls.errorbar(bestfit, y_pos, xerr=uncertainty, fmt="o", color="k")
 
@@ -257,9 +244,6 @@ def ranking(
         fontsize="large",
     )
 
-    if not MPL_GEQ_36:
-        fig.tight_layout(rect=[0, 0, 1.0, 1 - leg_space])  # pragma: no cover
-
     utils._save_and_close(fig, figure_path, close_figure)
     return fig
 
@@ -291,7 +275,7 @@ def scan(
     Returns:
         matplotlib.figure.Figure: the likelihood scan figure
     """
-    mpl.style.use(MPL_STYLE)
+    mpl.style.use("petroff10")
     fig, ax = plt.subplots(layout="constrained")
 
     y_lim = max(par_nlls) * 1.2  # upper y-axis limit, 20% headroom
@@ -311,7 +295,7 @@ def scan(
     # Gaussian at best-fit parameter value for reference
     val_grid = np.linspace(par_vals[0], par_vals[-1], 100)
     gaussian_approx = [((par_val - par_mle) / par_unc) ** 2 for par_val in val_grid]
-    ax.plot(val_grid, gaussian_approx, "--", color="C5", label="Gaussian approximation")
+    ax.plot(val_grid, gaussian_approx, "--", color="C9", label="Gaussian approximation")
 
     # scan results
     ax.plot(par_vals, par_nlls, "-", color="C0")

tests/visualize/reference/data_mc.png

@@ -25,10 +25,7 @@ def test_correlation_matrix(tmp_path):
     fname = tmp_path / "fig_from_return.png"
 
     # adjust layout behavior, see https://github.com/matplotlib/matplotlib/issues/21742
-    if plot_result.MPL_GEQ_36:
-        fig.set_layout_engine(None)
-    else:
-        fig.set_constrained_layout(False)
+    fig.set_layout_engine(None)
 
     fig.savefig(fname)
     assert (
@@ -88,16 +85,15 @@ def test_ranking(tmp_path):
         impact_postfit_down,
         figure_path=fname,
     )
-    # large tolerance needed here, possibly related to lack of set_tight_layout usage
     assert (
-        compare_images("tests/visualize/reference/ranking.png", str(fname), 50) is None
+        compare_images("tests/visualize/reference/ranking.png", str(fname), 0) is None
     )
 
     # compare figure returned by function
     fname = tmp_path / "fig_from_return.png"
     fig.savefig(fname)
     assert (
-        compare_images("tests/visualize/reference/ranking.png", str(fname), 50) is None
+        compare_images("tests/visualize/reference/ranking.png", str(fname), 0) is None
     )
 
     # do not save figure, but close it