API: Do not return None from recfunctions.drop_fields

This return value was not documented and did not make any sense. There's no reason to have a special case here.

1 files changed, 5 insertions, 3 deletions

diff --git a/numpy/lib/recfunctions.py b/numpy/lib/recfunctions.py
index 40060b41a..8011f5363 100644
--- a/numpy/lib/recfunctions.py
+++ b/numpy/lib/recfunctions.py
@@ -527,6 +527,10 @@ def drop_fields(base, drop_names, usemask=True, asrecarray=False):
 
     Nested fields are supported.
 
+    ..versionchanged: 1.18.0
+        `drop_fields` returns an array with 0 fields if all fields are dropped,
+        rather than returning ``None`` as it did previously.
+
     Parameters
     ----------
     base : array
@@ -566,7 +570,7 @@ def drop_fields(base, drop_names, usemask=True, asrecarray=False):
             current = ndtype[name]
             if name in drop_names:
                 continue
-            if current.names:
+            if current.names is not None:
                 descr = _drop_descr(current, drop_names)
                 if descr:
                     newdtype.append((name, descr))
@@ -575,8 +579,6 @@ def drop_fields(base, drop_names, usemask=True, asrecarray=False):
         return newdtype
 
     newdtype = _drop_descr(base.dtype, drop_names)
-    if not newdtype:
-        return None
 
     output = np.empty(base.shape, dtype=newdtype)
     output = recursive_fill_fields(base, output)