matplotlib · tacaswell · Feb 11, 2020 · Feb 11, 2020
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -6608,6 +6608,8 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
 
         if bins is None:
             bins = rcParams['hist.bins']
+        if isinstance(bins, str) and bins == 'np_default':
+            bins = None
 
         # Validate string inputs here to avoid cluttering subsequent code.
         cbook._check_in_list(['bar', 'barstacked', 'step', 'stepfilled'],
@@ -6633,7 +6635,7 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
         if bin_range is not None:
             bin_range = self.convert_xunits(bin_range)
 
-        if not cbook.is_scalar_or_string(bins):
+        if bins is not None and not cbook.is_scalar_or_string(bins):
             bins = self.convert_xunits(bins)
 
         # We need to do to 'weights' what was done to 'x'
@@ -6687,8 +6689,12 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
                 _w = np.concatenate(w)
             else:
                 _w = None
-            bins = np.histogram_bin_edges(
-                np.concatenate(x), bins, bin_range, _w)
+            nbe_kwargs = {'range': bin_range,
+                          'weights': _w}
+            if bins is not None:
+                nbe_kwargs['bins'] = bins
+            bins = np.histogram_bin_edges(np.concatenate(x),
+                                          **nbe_kwargs)
         else:
             hist_kwargs['range'] = bin_range
 
@@ -6702,7 +6708,11 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
         for i in range(nx):
             # this will automatically overwrite bins,
             # so that each histogram uses the same bins
-            m, bins = np.histogram(x[i], bins, weights=w[i], **hist_kwargs)
+            h_kwargs = {'weights': w[i], **hist_kwargs}
+            # This awkward way of calling
+            if bins is not None:
+                h_kwargs['bins'] = bins
+            m, bins = np.histogram(x[i], **h_kwargs)
             tops.append(m)
         tops = np.array(tops, float)  # causes problems later if it's an int
         if stacked:

diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -951,7 +951,7 @@ def validate_cycler(s):
 
 
 def validate_hist_bins(s):
-    valid_strs = ["auto", "sturges", "fd", "doane", "scott", "rice", "sqrt"]
+    valid_strs = ["auto", "sturges", "fd", "doane", "scott", "rice", "sqrt", "np_default"]
     if isinstance(s, str) and s in valid_strs:
         return s
     try:
@@ -962,7 +962,7 @@ def validate_hist_bins(s):
         return validate_floatlist(s)
     except ValueError:
         pass
-    raise ValueError("'hist.bins' must be one of {}, an int or"
+    raise ValueError("'hist.bins' must be one of {}, None, an int or"
                      " a sequence of floats".format(valid_strs))
 
 
@@ -1052,7 +1052,7 @@ def validate_webagg_address(s):
     'hatch.linewidth': [1.0, validate_float],
 
     ## Histogram properties
-    'hist.bins': [10, validate_hist_bins],
+    'hist.bins': ['np_default', validate_hist_bins],
 
     ## Boxplot properties
     'boxplot.notch': [False, validate_bool],

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -6187,6 +6187,20 @@ def test_hist_auto_bins():
     assert bins[-1] >= 6
 
 
+
+def test_hist_np_default_bins():
+
+    with plt.rc_context({'hist.bins': 'np_default'}):
+        _, edges, _ = plt.hist([[1, 2, 3], [3, 4, 5, 6]])
+        # this encodes that numpy's default is bins=10 -> 11 edges
+        assert len(edges) == 11
+
+    _, bins, _ = plt.hist([[1, 2, 3], [3, 4, 5, 6]], bins='np_default')
+    # this encodes that numpy's default is bins=10  -> 11 edges
+    len(edges) == 11
+
+
+
 def test_hist_nan_data():
     fig, (ax1, ax2) = plt.subplots(2)
 

diff --git a/lib/matplotlib/tests/test_rcparams.py b/lib/matplotlib/tests/test_rcparams.py
@@ -326,6 +326,7 @@ def generate_validator_testcases(valid):
          'success': (('auto', 'auto'),
                      ('fd', 'fd'),
                      ('10', 10),
+                     ('np_default', 'np_default'),
                      ('1, 2, 3', [1, 2, 3]),
                      ([1, 2, 3], [1, 2, 3]),
                      (np.arange(15), np.arange(15))

diff --git a/matplotlibrc.template b/matplotlibrc.template
@@ -595,7 +595,7 @@
 ## ***************************************************************************
 ## * HISTOGRAM PLOTS                                                         *
 ## ***************************************************************************
-#hist.bins : 10  ## The default number of histogram bins or 'auto'.
+#hist.bins : np_default  ## The default number of histogram bins or 'auto'.
 
 
 ## ***************************************************************************