ENH: Adds errorbar.capthick and errorbar.elinewidth to mplstyle (#31202)

Hannan7812 · Copilot · timhoffm · web-flow · commit e3d6dfc70353 · 2026-03-03T02:25:17.000+01:00
* Added 2 new rcparams: errorbar.capthick and errorbar.elinewidth * Modified _axes.py to properly render the rcparams * Fixed minor formatting to pass linter tests * Update lib/matplotlib/mpl-data/matplotlibrc Fixed documentation formatting Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Adressed reviewer comments and added a test * DOC: Add sections to rcParams documentation * Apply suggestion from @timhoffm * Update lib/matplotlib/tests/test_axes.py Incorporated suggestion to satisfy linting rule Co-authored-by: AlbertUnruh <73029826+AlbertUnruh@users.noreply.github.com> * Update lib/matplotlib/tests/test_axes.py Incorporated suggestion to pass linting test W291 Co-authored-by: AlbertUnruh <73029826+AlbertUnruh@users.noreply.github.com> * Moved capthick to line 4174 --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Co-authored-by: AlbertUnruh <73029826+AlbertUnruh@users.noreply.github.com>
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -4154,6 +4154,7 @@ def _upcast_err(err):
 
         # Make the style dict for the line collections (the bars).
         eb_lines_style = {**base_style, 'color': ecolor}
+        elinewidth = mpl._val_or_rc(elinewidth, "errorbar.elinewidth")
 
         if elinewidth is not None:
             eb_lines_style['linewidth'] = elinewidth
@@ -4170,6 +4171,8 @@ def _upcast_err(err):
         # Make the style dict for caps (the "hats").
         eb_cap_style = {**base_style, 'linestyle': 'none'}
         capsize = mpl._val_or_rc(capsize, "errorbar.capsize")
+        capthick = mpl._val_or_rc(capthick, "errorbar.capthick")
+
         if capsize > 0:
             eb_cap_style['markersize'] = 2. * capsize
         if capthick is not None:
diff --git a/lib/matplotlib/mpl-data/matplotlibrc b/lib/matplotlib/mpl-data/matplotlibrc
@@ -662,6 +662,8 @@
 ## * ERRORBAR PLOTS                                                          *
 ## ***************************************************************************
 #errorbar.capsize: 0  # length of end cap on error bars in pixels
+#errorbar.capthick: None  # thickness of end cap on error bars in points
+#errorbar.elinewidth: None  # line width of error bar lines in points
 
 
 ## ***************************************************************************
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -1114,6 +1114,8 @@ def _convert_validator_spec(key, conv):
 
     # errorbar props
     "errorbar.capsize": validate_float,
+    "errorbar.capthick": validate_float_or_None,
+    "errorbar.elinewidth": validate_float_or_None,
 
     # axis props
     # alignment of x/y axis title
@@ -2918,6 +2920,17 @@ class _Subsection:
         validator=validate_float,
         description="length of end cap on error bars in pixels"
     ),
+    _Param(
+        "errorbar.capthick",
+        default=None,
+        validator=validate_float_or_None,
+        description="thickness of end cap on error bars in points."),
+    _Param(
+        "errorbar.elinewidth",
+        default=None,
+        validator=validate_float_or_None,
+        description="line width of the error bar lines in points."
+    ),
     _Section("Histogram plots"),
     _Param(
         "hist.bins",
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -10155,3 +10155,22 @@ def test_animated_artists_not_drawn_by_default():
 
     mocked_im_draw.assert_not_called()
     mocked_ln_draw.assert_not_called()
+
+
+def test_errorbar_uses_rcparams():
+    with mpl.rc_context({
+        "errorbar.capsize": 5.0,
+        "errorbar.capthick": 2.5,
+        "errorbar.elinewidth": 1.75,
+    }):
+        fig, ax = plt.subplots()
+        eb = ax.errorbar([0, 1, 2], [1, 2, 3], yerr=[0.1, 0.2, 0.3], fmt="none")
+
+    data_line, caplines, barlinecols = eb.lines
+    assert data_line is None
+    assert caplines
+
+    assert_allclose([cap.get_markersize() for cap in caplines], 10.0)
+    assert_allclose([cap.get_markeredgewidth() for cap in caplines], 2.5)
+    for barcol in barlinecols:
+        assert_allclose(barcol.get_linewidths(), 1.75)
diff --git a/lib/matplotlib/typing.py b/lib/matplotlib/typing.py
@@ -281,6 +281,8 @@
     "date.interval_multiples",
     "docstring.hardcopy",
     "errorbar.capsize",
+    "errorbar.capthick",
+    "errorbar.elinewidth",
     "figure.autolayout",
     "figure.constrained_layout.h_pad",
     "figure.constrained_layout.hspace",
