Revert "WIP"

This reverts commit 576c394.

Author: dcherian

flox/core.py

@@ -651,30 +651,19 @@ def factorize_(
 
             found_groups.append(np.array(expect))
         else:
-            idx, groups = pd.factorize(flat, sort=sort)  # type: ignore[arg-type]
             if expect is not None and reindex:
-                assert sort
-                # https://stackoverflow.com/questions/5036816/numpy-lookup-map-or-point/5036900#5036900
-                # sorter = np.argsort(expect)
-                # groups = expect[(sorter,)] if sort else expect
-                #ii = np.argsort(groups)
-                #C = np.digitize(idx, groups[ii]) - 1
-                #idx = ii[C]
-                # key=np.argsort(groups)
-                # idx=key[groups[key].searchsorted(idx)]
-                inds = np.searchsorted(expect, groups)
-                # print(groups, inds)
-                mask = ~np.isin(groups, expect) | (inds == len(expect))
-                codes_to_nan_out = np.arange(len(groups))[mask]
-                print(codes_to_nan_out, groupvar.shape, len(groups))
-                # codes_to_nan_out, groups, groups[codes_to_nan_out]
-                # key=np.argsort(expect)
-                # key = np.arange(len(expect))
-                # idx=key[groups[key].searchsorted(idx)]
-                idx = idx[]
-                idx[np.isin(idx, codes_to_nan_out)] = -1
-                print(np.unique(idx))
-
+                sorter = np.argsort(expect)
+                groups = expect[(sorter,)] if sort else expect
+                idx = np.searchsorted(expect, flat, sorter=sorter)
+                mask = ~np.isin(flat, expect) | isnull(flat) | (idx == len(expect))
+                if not sort:
+                    # idx is the index in to the sorted array.
+                    # if we didn't want sorting, unsort it back
+                    idx[(idx == len(expect),)] = -1
+                    idx = sorter[(idx,)]
+                idx[mask] = -1
+            else:
+                idx, groups = pd.factorize(flat, sort=sort)  # type: ignore[arg-type]
 
             found_groups.append(np.array(groups))
         factorized.append(idx.reshape(groupvar.shape))