test edge cases

tests/test_table.py

@@ -102,6 +102,22 @@ def test_table_getitem_col_row():
         assert str(e) == "Cannot find 'notthere' in column 'name'"
 
 
+def test_table_getitem_edge_cases():
+    with pytest.raises(KeyError) as e:
+        t[:]
+        assert str(e).startswith("Invalid arguments")
+
+    with pytest.raises(KeyError) as e:
+        t[()]
+        assert str(e).startswith("Empty selection")
+
+    assert t[("betx", 1)] == t["betx",1]
+
+    assert t[("betx",)][2] == t["betx"][2]
+
+
+
+
 def test_table_numpy_string():
     tab = Table(dict(name=np.array(["a", "b$b"]), val=np.array([1, 2])))
     assert tab["val", tab.name[1]] == 2
@@ -254,6 +270,16 @@ def test_cols_iter():
 def test_cols_get_index_unique():
     assert len(set(t.cols.get_index_unique())) == len(t)
 
+def test_cols_expression():
+    data = {
+        "name": np.array(["a", "b", "c"]),
+        "c1": np.array([1, 2, 3]),
+        "c2": np.array([4, 5, 6]),
+    }
+    table = Table(data)
+    assert np.array_equal(table.cols["c1+c2"]["c1+c2"], data["c1"] + data["c2"])
+    assert np.array_equal(table.cols["c1+1.34"]["c1+1.34"], table["c1"]+1.34)
+
 ## Table rows tests
 
 def test_rows_get_index():

xdeps/table.py

@@ -508,7 +508,7 @@ def _select_cols(self, cols):
         """Select a subtable by iterable of column names."""
         data = {}
         for cc in cols:
-            data[cc] = self._data[cc]
+            data[cc] = self[cc]
         for kk in self.keys(exclude_columns=True):
             data[kk] = self._data[kk]
         if self._index not in cols:
@@ -542,9 +542,13 @@ def __getitem__(self, args):
             if len(args) == 0:
                 col = None
                 row = None
+                raise KeyError(
+                    f"Empty selection for <Table id={id(self)}>."
+                )
             elif len(args) == 1:
                 col = args[0]
                 row = None
+                return self[col]
             elif len(args) == 2:
                 col = args[0]
                 row = args[1]
@@ -571,10 +575,10 @@ def __getitem__(self, args):
                     idx = row
                 return col[idx]
             else:
-                raise ValueError(
+                raise KeyError(
                     f"Too many arguments {args} for <Table id={id(self)}>."
                 )
-        raise ValueError(f"Invalid arguments {args} for <Table id={id(self)}>.")
+        raise KeyError(f"Invalid arguments {args} for <Table id={id(self)}>.")
 
     def show(
         self,