fix: improve ak.from_iter performance for long (axis=0) arrays (#1614)

Fixes #1588
scikit-hep · Aug 22, 2022 · c045715 · c045715
1 parent b1f7792
commit c045715
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Showing 2 changed files with 4 additions and 7 deletions.
diff --git a/src/awkward/_v2/operations/ak_from_iter.py b/src/awkward/_v2/operations/ak_from_iter.py
@@ -83,12 +83,11 @@ def _impl(iterable, highlevel, behavior, allow_record, initial, resize):
             )
 
     builder = ak.layout.ArrayBuilder(initial=initial, resize=resize)
-    for x in iterable:
-        builder.fromiter(x)
+    builder.fromiter(iterable)
 
     formstr, length, buffers = builder.to_buffers()
     form = ak._v2.forms.from_json(formstr)
 
     return ak._v2.operations.from_buffers(
         form, length, buffers, highlevel=highlevel, behavior=behavior
-    )
+    )[0]
diff --git a/src/awkward/operations/convert.py b/src/awkward/operations/convert.py
@@ -887,10 +887,8 @@ def from_iter(
             )
 
     out = ak.layout.ArrayBuilder(initial=initial, resize=resize)
-    for x in iterable:
-        out.fromiter(x)
-    layout = out.snapshot()
-    return ak._util.maybe_wrap(layout, behavior, highlevel)
+    out.fromiter(iterable)
+    return ak._util.maybe_wrap(out[0], behavior, highlevel)
 
 
 def to_list(array):