fix: bool pick for 2D+ (#398)

Author: henryiii

src/boost_histogram/_internal/hist.py

@@ -565,6 +565,9 @@ def __getitem__(self, index):  # noqa: C901
 
         indexes = self._compute_commonindex(index)
 
+        # Workaround for missing "pick" and no reduction on bool axes
+        pick_bool = {}
+
         # If this is (now) all integers, return the bin contents
         # But don't try *dict!
         if not hasattr(indexes, "items"):
@@ -579,7 +582,11 @@ def __getitem__(self, index):  # noqa: C901
         # Compute needed slices and projections
         for i, ind in enumerate(indexes):
             if hasattr(ind, "__index__"):
-                ind = slice(ind.__index__(), ind.__index__() + 1, sum)
+                if isinstance(self.axes[i]._ax, _core.axis.boolean):
+                    pick_bool[i] = ind
+                    ind = slice(None, None, sum)
+                else:
+                    ind = slice(ind.__index__(), ind.__index__() + 1, sum)
 
             elif not isinstance(ind, slice):
                 raise IndexError(
@@ -612,6 +619,13 @@ def __getitem__(self, index):  # noqa: C901
 
                 slices.append(_core.algorithm.slice_and_rebin(i, start, stop, merge))
 
+        for i, select in pick_bool.items():
+            self = self.copy()
+            view = self.view(flow=True)
+            view[
+                tuple(~select if j == i else slice(None) for j in range(self.ndim))
+            ] = 0
+
         reduced = self._hist.reduce(*slices)
 
         if not integrations:

tests/test_histogram.py

@@ -626,6 +626,18 @@ def test_pickle_1():
     assert a == b
 
 
+def test_pick_bool():
+    a = bh.Histogram(bh.axis.Boolean(), bh.axis.Boolean(metadata={"one": 1}))
+
+    a.fill([True, True, False, False], [True, False, True, True])
+    a.fill([True, True, True], True)
+
+    assert_array_equal(a[True, :].view(), [1, 4])
+    assert_array_equal(a[False, :].view(), [0, 2])
+    assert_array_equal(a[:, False].view(), [0, 1])
+    assert_array_equal(a[:, True].view(), [2, 4])
+
+
 def test_pickle_bool():
     a = bh.Histogram(bh.axis.Boolean(), bh.axis.Boolean(metadata={"one": 1}))
     assert isinstance(a, bh.Histogram)